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dosemu2 / fdpp

FreeDOS plus-plus, 64bit DOS
GNU General Public License v3.0
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Installed block device unavailable under FDPP #85

Closed andrewbird closed 5 years ago

andrewbird commented 5 years ago

After installing a block device driver with device=emudsk.sys the drive is unavailable under FDPP, but is fine under FreeDOS

$ cat test-imagedir/dosemu.conf
$_lpt1 = ""
$_hdimage = "dXXXXs/c:hdtype1 +1"
$_floppy_a = ""

Current FDPP

Based on FreeDOS sources (C) Pasquale J. Villani and The FreeDOS Project.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

C: HD1, Pri[ 1], CHS=    0-1-1, start=     0 MB, size=    10 MB
D: HD2, Pri[ 1], CHS=    0-1-1, start=     0 MB, size=  2000 MB
E: HD3, Pri[ 1], CHS=    0-1-1, start=     0 MB, size=  2000 MB
F: HD4, Pri[ 1], CHS=    0-1-1, start=     0 MB, size=  2000 MB
EMUFS host file and print access available
Dosemu EMUDSK installed as drive G:
Process 0 starting: C:\command.com /P /E:256

FreeCom version 0.84-pre2 XMS_Swap [Aug 28 2006 00:29:00]
C:\>prompt $P$G
C:\>path c:\bin;c:\gnu;c:\dosemu
C:\>unix -s DOSEMU_VERSION
UNIX: option -s is deprecated, use system.com instead
C:\>unix -e
UNIX: option -e is deprecated, use system.com instead
C:\>g:
Invalid drive G:.

You can see that the driver is loaded as G:

dosdebug> devs
dosdebug> 
DOS Devices

0000:0dd8 Char 'NUL     '
  Attributes: 0x8004 (Char, NULDEV)
  Routines: Strategy(0000:0e78), Interrupt(0000:0e7d)

02a8:0000 Block (1 Units)
  Attributes: 0x0000 (Block)
  Routines: Strategy(02a8:006b), Interrupt(02a8:0084)

029f:0000 Char 'EMUFS$  '
  Attributes: 0x8000 (Char)
  Routines: Strategy(029f:0036), Interrupt(029f:0041)

<snip>

Device driver was loaded okay and remains resident in memory

dosdebug> mcbs
dosdebug> 

ADDR(LOW) PARAS  OWNER
0290:0000 0x04db [DOS]
  => ADDR      PARAS TYPE USAGE
     0291:0000 0x000c [F] Files
     029e:0000 0x0008 [D] Driver (EMUFS)
     02a7:0000 0x000d [D] Driver (EMUDSK)
     02b5:0000 0x0004 [E] Driver Extension
     02ba:0000 0x0020 [B] Buffers
     02db:0000 0x029e [B] Buffers
     057a:0000 0x00cf [F] Files
     064a:0000 0x008f [L] CDS Array
     06da:0000 0x0080 [S] Stacks
     075b:0000 0x0010 [B] Buffers
076c:0000 ------ [LINK]
0817:0000 0x0006 [FREE]
081e:0000 0x12c1 [COMMAND]
1ae0:0000 0x7e63 [FREE]
9944:0000 0x0619 [COMMAND]
9f5e:0000 0x0090 [COMMAND]
9fef:0000 0x0010 [COMMAND] (END)

CDS entry seems to have the flags zeroed

064b:0210 47 3A 5C 00 00 00 00 00 00 00 00 00 00 00 00 00  G:\.............
064b:0220 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
064b:0230 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
064b:0240 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
064b:0250 00 00 00 00 00 00 00 00 00 FF FF FF FF FF FF 02  ..........
064b:0260 00 00 00 00 00 00 00 00

And DPB for drive G: is missing

Now FreeDOS

$ mv test-imagedir/dXXXXs/c/fdppconf.sys test-imagedir/dXXXXs/c/config.sys
$ cp /tmp/kernel.sys test-imagedir/dXXXXs/c/.
Ask for help in mail list: linux-msdos@vger.kernel.org

FreeDOS kernel build 2036 cvs [version Aug 18 2006 compiled Aug 18 2006]
Kernel compatibility 7.10 - WATCOMC - 80386 CPU required - FAT32 support

(C) Copyright 1995-2006 Pasquale J. Villani and The FreeDOS Project.
All Rights Reserved. This is free software and comes with ABSOLUTELY NO
WARRANTY; you can redistribute it and/or modify it under the terms of the
GNU General Public License as published by the Free Software Foundation;
either version 2, or (at your option) any later version.

C: HD1, Pri[ 1], CHS=    0-1-1, start=     0 MB, size=    10 MB
D: HD2, Pri[ 1], CHS=    0-1-1, start=     0 MB, size=  2000 MB
E: HD3, Pri[ 1], CHS=    0-1-1, start=     0 MB, size=  2000 MB
F: HD4, Pri[ 1], CHS=    0-1-1, start=     0 MB, size=  2000 MB
EMUFS host file and print access available
Dosemu EMUDSK installed as drive G:

FreeCom version 0.84-pre2 XMS_Swap [Aug 28 2006 00:29:00]
C:\>prompt $P$G
C:\>path c:\bin;c:\gnu;c:\dosemu
C:\>unix -s DOSEMU_VERSION
UNIX: option -s is deprecated, use system.com instead
C:\>unix -e
UNIX: option -e is deprecated, use system.com instead
C:\>g:
G:\>copy c:\autoexec.bat
c:\autoexec.bat => .\autoexec.bat
G:\>dir
 Volume in drive G has no label
 Directory of G:\

AUTOEXEC BAT            76  06-29-19  1:00a
         1 file(s)             76 bytes
         0 dir(s)     134,066,176 bytes free
G:\>
stsp commented 5 years ago

So we know DPB is good. What's next? CDS?

andrewbird commented 5 years ago

yes, to check the flags and dpb pointer within the cds entry.

andrewbird commented 5 years ago 
dosdebug> d 0669:0210
dosdebug> 

0669:0210 47 3A 5C 00 00 00 00 00 00 00 00 00 00 00 00 00  G:\.............
0669:0220 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0669:0230 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0669:0240 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0669:0250 00 00 00 00 40 00 00 D4 02 FF FF FF FF FF FF 02  ....@..T..
0669:0260 00 00 00 00 00 00 00 00 48 3A 5C 00 00 00 00 00  ........

find DPB pointer within CDS

dosdebug> d 0669:0255
dosdebug> 

0669:0255 00 00 D4 02 FF FF FF FF FF FF 02 00 00 00 00 00  ..T.......
0669:0265 00 00 00 48 3A 5C 00 00 00 00 00 00 00 00 00 00  ...H:\..........
0669:0275 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0669:0285 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0669:0295 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
0669:02a5 00 00 00 00 00 00 00 00 00 00 00 00 FF FF FF FF  ............
0669:02b5 FF FF 02 00 00 00 00 00 00 00 00 49 3A 5C 00 00  .........I:\..
0669:02c5 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................

DPB entry

dosdebug> d 02d4:0000
dosdebug> 

02d4:0000 06 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02d4:0010 00 00 00 00 00 B2 02 00 FF FF FF FF FF 00 00 00  .....2.....
02d4:0020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02d4:0030 00 00 00 00 00 00 00 00 00 00 00 00 00 7E 06 FF  .............~.
02d4:0040 42 D9 02 20 00 00 00 00 00 00 00 00 00 00 00 00  BY. ............
02d4:0050 E8 8C 0D 68 0A DD 15 58 87 0B BD 2C 74 87 EE 2E  h..h.].X..=,t.n.
02d4:0060 68 E4 CB A8 42 6F D8 5A 95 63 1A E5 F3 B0 4A 0F  hdK(BoXZ.c.es0J.
02d4:0070 39 F4 64 3A 38 56 29 2A 3A 37 38 1B 05 32 50 26  9td:8V)*:78..2P&

which matches

00D9:1B19 (F:)
  driver unit: 5
  bytes_per_sect = 0x200
  last_sec_in_clust = 0x3f
  sec_shift = 0x6
  reserv_secs = 0x1
  num_fats = 0x2
  root_ents = 0x200
  data_start = 0x217
  max_clu = 0xfa00
  sects_per_fat = 0xfb
  first_dir_off = 0x1f7
  device driver = 0070:0618
  media_id = 0xf8
  accessed = 0x0
  next_DPB = 02D4:0000
  first_free_clu = 0x0
  fre_clusts = 0xffff

02D4:0000 (G:)
  driver unit: 0
  bytes_per_sect = 0x0
  last_sec_in_clust = 0x0
  sec_shift = 0x0
  reserv_secs = 0x0
  num_fats = 0x0
  root_ents = 0x0
  data_start = 0x0
  max_clu = 0x0
  sects_per_fat = 0x0
  first_dir_off = 0x0
  device driver = 02B2:0000
  media_id = 0x0
  accessed = 0xff
  next_DPB = FFFF:FFFF
  first_free_clu = 0x0
  fre_clusts = 0x0

So that looks good except the geometry is not initialised in the DPB for G: drive.

andrewbird commented 5 years ago

Flags are good at CDS + 0x043 #define CDS_FLAG_READY 0x4000

stsp commented 5 years ago

C_MEDIACHK ioctl returns error and media_check() then throws int24 instead of building BPB.

andrewbird commented 5 years ago

So something curious about the driver's media_check routine, it correctly sets 'media changed' in the request header, but then after consulting some local vars it returns error status. That's why the bpb never gets set.

An MS link map file I built if you are interested. usermap load-ms xmsdsk.map 0x02b2 or wherever devs tells you it was loaded.

  Address         Publics by Value                                              
 0000:0018       xmsdsk_rh_pointer                                              
 0000:00a6       xmsdsk_strategy                                                
 0000:00b2       xmsdsk_interrupt                                               
# Command table                                                                 
# 02b2:001c 01 02 DE 00 F8 00 07 01 1A 01 DA 00 DA 00 DA 00  ..^.x.....Z.Z.Z.   
# 02b2:002c 16 01 16 01 DA 00 DA 00 DA 00 00 02 01 01 00 01  ....Z.Z.Z.......   
# 02b2:003c 00 00 00 00 F8 00 00 08 00 01 00 00 00 00 00 00  ....x...........   
# 02b2:004c 00 00 00 90 06 FF 00 00 00 00 00 00 00 00 00 00  ...............    
# 02b2:005c 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................   
 0000:0201       xmsdsk_initialisation                                          
 0000:00de       xmsdsk_media_check                                             
 0000:00f8       xmsdsk_get_bpb                                                 
 0000:0107       xmsdsk_ioctl_input                                             
 0000:011a       xmsdsk_input                                                   
 0000:00da       xmsdsk_dummy                                                   
 0000:00da       xmsdsk_dummy                                                   
 0000:00da       xmsdsk_dummy                                                   
 0000:0116       xmsdsk_output                                                  
 0000:0116       xmsdsk_output                                                  
 0000:00da       xmsdsk_dummy                                                   
 0000:00da       xmsdsk_dummy                                                   
 0000:00da       xmsdsk_dummy                                                   
#                                                                               
 0000:011d       xmsdsk_common_io                                               
 0000:0036       xmsdsk_data_bpb                                                
 0000:0051       xmsdsk_data_media_changed                                      
 0000:004b       xmsdsk_magic_word_1                                            
 0000:004d       xmsdsk_magic_word_2

The magic vars that stop status being returned as good for media check are are named as such. I couldn't see them set during the initialisation, and current values are zero.

dosdebug> 
reading MSLINK map file 'xmsdsk.map'
symbol table now contains 274 symbol(s)

dosdebug> bp xmsdsk_interrupt
dosdebug> bp xmsdsk_strategy
dosdebug> g
dosdebug> 
system state: stopped
AX=00a6  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08ec  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3206
CS:IP=02b2:00a6       SS:SP=00d9:08ec

xmsdsk_strategy:
02b2:00a6 2E891E1800       mov  cs:[0018],bx
dosdebug> t
dosdebug> 
system state: stopped
AX=00a6  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08ec  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=02b2:00ab       SS:SP=00d9:08ec

02b2:00ab 2E8C061A00       mov  cs:[001A],es
dosdebug> 
dosdebug> 
system state: stopped
AX=00a6  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08ec  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=02b2:00b0       SS:SP=00d9:08ec

02b2:00b0 CB               retf
dosdebug> 
dosdebug> 
system state: stopped
AX=00a6  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08f0  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=078b:03ee       SS:SP=00d9:08f0

078b:03ee 5F               pop  di
dosdebug> 
dosdebug> 
system state: stopped
AX=00a6  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08f2  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=078b:03ef       SS:SP=00d9:08f2

078b:03ef 5E               pop  si
dosdebug> 
dosdebug> 
system state: stopped
AX=00a6  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08f2  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=078b:03ef       SS:SP=00d9:08f2

078b:03ef 5E               pop  si
dosdebug> 
dosdebug> 
system state: stopped
AX=00a6  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08f4  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=078b:03f0       SS:SP=00d9:08f4

078b:03f0 8B4408           mov  ax,[si+08]
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08f4  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=078b:03f3       SS:SP=00d9:08f4

078b:03f3 894604           mov  [bp+04],ax
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08f4  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=078b:03f6       SS:SP=00d9:08f4

078b:03f6 FF5E04           call far word [bp+04]
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08f0  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=02b2:00b2       SS:SP=00d9:08f0

xmsdsk_interrupt:
02b2:00b2 9C               pushf 
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08f0  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=02b2:00b2       SS:SP=00d9:08f0

xmsdsk_interrupt:
02b2:00b2 9C               pushf 
dosdebug>
dosdebug> t
dosdebug> 
system state: stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08ee  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000b3306
CS:IP=02b2:00b3       SS:SP=00d9:08ee

02b2:00b3 60               pusha 
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08de  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=02b2:00b4       SS:SP=00d9:08de

02b2:00b4 1E               push ds
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08dc  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=02b2:00b5       SS:SP=00d9:08dc

02b2:00b5 06               push es
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08da  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=02b2:00b6       SS:SP=00d9:08da

02b2:00b6 0E               push cs
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08d8  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=02b2:00b7       SS:SP=00d9:08d8

02b2:00b7 1F               pop  ds
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08da  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=02b2:00b8       SS:SP=00d9:08da

02b2:00b8 C43E1800         les  di,[0018]
dosdebug> 
02b2:00bc 268A5D02         mov  bl,es:[di+02]
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=0301  CX=0000  DX=091c  SI=0000  DI=037c  SP=08da  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3306
CS:IP=02b2:00c0       SS:SP=00d9:08da

02b2:00c0 D0E3             shl  bl,1
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=0302  CX=0000  DX=091c  SI=0000  DI=037c  SP=08da  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3302
CS:IP=02b2:00c2       SS:SP=00d9:08da

02b2:00c2 32FF             xor  bh,bh
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=0002  CX=0000  DX=091c  SI=0000  DI=037c  SP=08da  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3346
CS:IP=02b2:00c4       SS:SP=00d9:08da

02b2:00c4 33C0             xor  ax,ax
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=0002  CX=0000  DX=091c  SI=0000  DI=037c  SP=08da  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3346
CS:IP=02b2:00c6       SS:SP=00d9:08da

02b2:00c6 FF971C00         call near word [bx+001C]
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=0002  CX=0000  DX=091c  SI=0000  DI=037c  SP=08d8  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3346
CS:IP=02b2:00de       SS:SP=00d9:08d8

xmsdsk_media_check:
02b2:00de 8A1E5100         mov  bl,[0051]
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=00ff  CX=0000  DX=091c  SI=0000  DI=037c  SP=08d8  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3346
CS:IP=02b2:00e2       SS:SP=00d9:08d8

02b2:00e2 26885D0E         mov  es:[di+0E],bl
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=00ff  CX=0000  DX=091c  SI=0000  DI=037c  SP=08d8  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3346
CS:IP=02b2:00e6       SS:SP=00d9:08d8

02b2:00e6 0ADB             or   bl,bl
dosdebug>
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=00ff  CX=0000  DX=091c  SI=0000  DI=037c  SP=08d8  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3386
CS:IP=02b2:00e8       SS:SP=00d9:08d8

02b2:00e8 790D             jns  00F7 ($+d)
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=00ff  CX=0000  DX=091c  SI=0000  DI=037c  SP=08d8  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3386
CS:IP=02b2:00ea       SS:SP=00d9:08d8

02b2:00ea 8B1E4B00         mov  bx,[004B]
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=0000  CX=0000  DX=091c  SI=0000  DI=037c  SP=08d8  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3386
CS:IP=02b2:00ee       SS:SP=00d9:08d8

02b2:00ee 0B1E4D00         or   bx,[004D]
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=0000  CX=0000  DX=091c  SI=0000  DI=037c  SP=08d8  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3346
CS:IP=02b2:00f2       SS:SP=00d9:08d8

02b2:00f2 7503             jne  00F7 ($+3)
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=0000  CX=0000  DX=091c  SI=0000  DI=037c  SP=08d8  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3346
CS:IP=02b2:00f4       SS:SP=00d9:08d8

02b2:00f4 B80180           mov  ax,8001
dosdebug> 
dosdebug> 
system state: stopped
AX=8001  BX=0000  CX=0000  DX=091c  SI=0000  DI=037c  SP=08d8  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3346
CS:IP=02b2:00f7       SS:SP=00d9:08d8

02b2:00f7 C3               ret
dosdebug> 
dosdebug> 
system state: stopped
AX=8001  BX=0000  CX=0000  DX=091c  SI=0000  DI=037c  SP=08da  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3346
CS:IP=02b2:00ca       SS:SP=00d9:08da

02b2:00ca 0D0001           or   ax,0100
dosdebug>
dosdebug> 
dosdebug> 
system state: stopped
AX=8101  BX=0000  CX=0000  DX=091c  SI=0000  DI=037c  SP=08da  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3382
CS:IP=02b2:00cd       SS:SP=00d9:08da

02b2:00cd C43E1800         les  di,[0018]
dosdebug> 
dosdebug> 
system state: stopped
AX=8101  BX=0000  CX=0000  DX=091c  SI=0000  DI=037c  SP=08da  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3382
CS:IP=02b2:00d1       SS:SP=00d9:08da

02b2:00d1 26894503         mov  es:[di+03],ax
dosdebug> 
dosdebug> 
system state: stopped
AX=8101  BX=0000  CX=0000  DX=091c  SI=0000  DI=037c  SP=08da  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3382
CS:IP=02b2:00d5       SS:SP=00d9:08da

02b2:00d5 07               pop  es
dosdebug> 
dosdebug> 
system state: stopped
AX=8101  BX=0000  CX=0000  DX=091c  SI=0000  DI=037c  SP=08dc  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3382
CS:IP=02b2:00d6       SS:SP=00d9:08dc

02b2:00d6 1F               pop  ds
dosdebug> 
dosdebug> 
system state: stopped
AX=8101  BX=0000  CX=0000  DX=091c  SI=0000  DI=037c  SP=08de  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3382
CS:IP=02b2:00d7       SS:SP=00d9:08de

02b2:00d7 61               popa 
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08ee  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000a3382
CS:IP=02b2:00d8       SS:SP=00d9:08ee

02b2:00d8 9D               popf 
dosdebug> 
dosdebug> 
system state: stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08f0  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000b3306
CS:IP=02b2:00d9       SS:SP=00d9:08f0

02b2:00d9 CB               retf
dosdebug>
stsp commented 5 years ago

If you patch jne at 02b2:00f2 to jmp, will it work then?

andrewbird commented 5 years ago

I tried something similar earlier in tweaking the status value to success. I got further on but ended up with a different (I/O I think) error.

Can you think of a reason it might do?

mov  bx,[004B]
or   bx,[004D]
stsp commented 5 years ago

Can you see what is there in these vars under freedos?

andrewbird commented 5 years ago

I saw them under dosdebug to be zero (in the media_check).

stsp commented 5 years ago

So even under freedos it returns an error? How is so?

andrewbird commented 5 years ago

Sorry I misunderstood you, I didn't try freedos(still struggling with FDPP != FreeDOS) yet, but will now.

andrewbird commented 5 years ago

Interestingly it doesn't check those values under freedos 1.20

dosdebug> 
system state: stopped
AX=0000  BX=0002  CX=02e7  DX=02e7  SI=0000  DI=037c  SP=0872  BP=0890
DS=02c5  ES=00d8  FS=0000  GS=0000  FL=000a3346
CS:IP=02c5:00c6       SS:SP=00d8:0872

02c5:00c6 FF971C00         call near word [bx+001C]
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=0002  CX=02e7  DX=02e7  SI=0000  DI=037c  SP=0870  BP=0890
DS=02c5  ES=00d8  FS=0000  GS=0000  FL=000a3346
CS:IP=02c5:00de       SS:SP=00d8:0870

02c5:00de 8A1E5100         mov  bl,[0051]
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=0001  CX=02e7  DX=02e7  SI=0000  DI=037c  SP=0870  BP=0890
DS=02c5  ES=00d8  FS=0000  GS=0000  FL=000a3346
CS:IP=02c5:00e2       SS:SP=00d8:0870

02c5:00e2 26885D0E         mov  es:[di+0E],bl
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=0001  CX=02e7  DX=02e7  SI=0000  DI=037c  SP=0870  BP=0890
DS=02c5  ES=00d8  FS=0000  GS=0000  FL=000a3346
CS:IP=02c5:00e6       SS:SP=00d8:0870

02c5:00e6 0ADB             or   bl,bl
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=0001  CX=02e7  DX=02e7  SI=0000  DI=037c  SP=0870  BP=0890
DS=02c5  ES=00d8  FS=0000  GS=0000  FL=000a3302
CS:IP=02c5:00e8       SS:SP=00d8:0870

02c5:00e8 790D             jns  00F7 ($+d)
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=0001  CX=02e7  DX=02e7  SI=0000  DI=037c  SP=0870  BP=0890
DS=02c5  ES=00d8  FS=0000  GS=0000  FL=000a3302
CS:IP=02c5:00f7       SS:SP=00d8:0870

02c5:00f7 C3               ret

but printing it shows

dosdebug> d 02c5:004b
dosdebug> 

02c5:004b 80 3E 00 00 90 06 01 01 00 00 00 00 00 00 00 00  .>..............
02c5:005b 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:006b 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:007b 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:008b 00 00 00 00 00 00 00 17 F5 00 F0 00 02 00 00 01  ........u.p.....
02c5:009b 00 00 1A 00 00 00 00 78 0A EC 02 2E 89 1E 18 00  .......x.l......
02c5:00ab 2E 8C 06 1A 00 CB 90 9C 60 1E 06 0E 1F C4 3E 18  .....K..`....D>.
02c5:00bb 00 26 8A 5D 02 D0 E3 32 FF 33 C0 FF 97 1C 00 0D  .&.].Pc23@....
stsp commented 5 years ago

So under fdpp, 0000:0051 xmsdsk_data_media_changed has -1 (media changed) and 0 (no info) under freedos. You can use gdb watchpoints with lowmem_base or mem_base and cpu_emu=vm86sim to see who puts -1 to that var. Btw why dosdebug doesn't print that var symbolically? Its not like it is ds:[0] that would get broken.

andrewbird commented 5 years ago

Media changed is initially -1, then after it's checked it changes to zero. It's never successful on fdpp, so doesn't change.

I don't know why the symbol isn't printed.

stsp commented 5 years ago

Media changed is initially -1, then after it's checked it changes to zero.

Then why on freedos it is immediately zero?

stsp commented 5 years ago

Then why on freedos it is immediately zero?

No, its 1, not changed.

02c5:00de 8A1E5100         mov  bl,[0051]
dosdebug> 
dosdebug> 
system state: stopped
AX=0000  BX=0001

But under fdpp its -1.

Where you got the symbols btw?

andrewbird commented 5 years ago

Wrote them by hand by reading the command table dump and knowing driver structure.

andrewbird commented 5 years ago

Then why on freedos it is immediately zero?

Because I have to wait for the driver to be loaded in order to set the breakpoint and load the symbols, I can't guarantee that media_check hasn't already been called and set the variable to 1.

andrewbird commented 5 years ago

Can you give me the magic gdb incantation to set a watchpoint for word at 02c5:004b?

andrewbird commented 5 years ago

I'm using this

watch *(unsigned short int *) &lowmem_base[(0x02c5<<4)+0x004b]

But it doesn't trap the change to

(gdb) p/x *(unsigned short int *) &lowmem_base[(0x02c5<<4)+0x004b]
$3 = 0x3e80

Just these

Thread 1 "dosemu.bin" hit Hardware watchpoint 1: *(unsigned short int *) &lowmem_base[(0x02c5<<4)+0x004b]

Old value = 7762
New value = 7782
0x080e7935 in fatfs_read (f=0x8aac920, buf=11040, pos=17281, len=1) at fatfs.c:345
345     MEMCPY_2DOS(buf, b, 0x200);
(gdb) next

Thread 1 "dosemu.bin" hit Hardware watchpoint 1: *(unsigned short int *) &lowmem_base[(0x02c5<<4)+0x004b]

Old value = 7782
New value = 29542
0x080e7935 in fatfs_read (f=0x8aac920, buf=11040, pos=17281, len=1) at fatfs.c:345
345     MEMCPY_2DOS(buf, b, 0x200);
stsp commented 5 years ago

2 things to try: use vm86sim and set the watchpoint ALSO to mem_base (with same treatment as lowmem_base)

andrewbird commented 5 years ago

Couldn't set two hardware breakpoints, so had to choose. I also note that mem_base == 0, even so setting watchpoint on *(unsigned short int *) &mem_base[(0x02c5<<4)+0x004b] didn't stop at at all.

Now using vm86sim, was fullsim before

stsp commented 5 years ago

Switch $_cpu_vm properly.

andrewbird commented 5 years ago

I set it now to "emulated" and now got to see

Thread 1 "dosemu.bin" hit Hardware watchpoint 1: *(unsigned short int *) &mem_base[(0x02c5<<4)+0x004b]

Old value = 7762
New value = 16000
0x081452ee in Gen_sim (op=23, mode=4099) at codegen-sim.c:663
663             *AR1.pwu = DR1.w.l;
(gdb) p/x *(unsigned short int *) &mem_base[(0x02c5<<4)+0x004b]
$5 = 0x3e80
(gdb) bt
#0  0x081452ee in Gen_sim (op=23, mode=4099) at codegen-sim.c:663
#1  0x081339b9 in _ModRM (opc=137 '\211', PC=12503, mode=4099) at modrm-gen.c:146
#2  0x08121839 in _Interp86 (PC=12503, basemode=3) at interp.c:1072
#3  0x0811d2ce in Interp86 (PC=1045789, mod0=3) at interp.c:395
#4  0x08131b7f in e_vm86 () at cpu-emu.c:1144
#5  0x0810f851 in do_vm86 (x=0x88dac40 <vm86u>) at do_vm86.c:433
#6  0x0810f8be in _do_vm86 () at do_vm86.c:455
#7  0x0811006b in run_vm86 () at do_vm86.c:590
#8  0x081100e7 in loopstep_run_vm86 () at do_vm86.c:614
#9  0x080affe7 in main (argc=11, argv=0xbffff704) at emu.c:422

setting set mhpdbgc.want_to_stop=1 allowed me to stop in the init section of the driver

dosdebug> u 02c5:0201
dosdebug> 

xmsdsk_initialisation:
02c5:0201 C8240000         enter 0024,00
02c5:0205 56               push si
02c5:0206 57               push di
02c5:0207 8C16D847         mov  [47D8],ss
02c5:020b 8926DA47         mov  [47DA],sp
02c5:020f 892EDC47         mov  [47DC],bp
02c5:0213 FA               cli
02c5:0214 8CD8             mov  ax,ds
02c5:0216 8ED0             mov  ss,ax
02c5:0218 BDDE49           mov  bp,49DE
02c5:021b A1DC47           mov  ax,[47DC]
02c5:021e 2B06DA47         sub  ax,[47DA]
dosdebug> 
dosdebug> 

02c5:0222 8BD5             mov  dx,bp
02c5:0224 2BD0             sub  dx,ax
02c5:0226 8BE2             mov  sp,dx
02c5:0228 FB               sti
02c5:0229 68823E           push 3E82
02c5:022c E82F23           call 255E ($+232f)
02c5:022f 59               pop  cx
02c5:0230 B430             mov  ah,30
02c5:0232 CD21             int  21
02c5:0234 A2673F           mov  [3F67],al
02c5:0237 3C03             cmp  al,03
02c5:0239 730B             jnc  0246 ($+b)
02c5:023b FF36A63D         push word [3DA6]
02c5:023f E81D04           call 065F ($+41d)
dosdebug> 
dosdebug> 

02c5:0242 59               pop  cx
02c5:0243 E9FE03           jmp  0644 ($+3fe)
02c5:0246 C41E1800         les  bx,[0018]
02c5:024a 268A4716         mov  al,es:[bx+16]
02c5:024e A25000           mov  [0050],al
02c5:0251 803E500000       cmp  byte [0050],00
02c5:0256 7C07             jl   025F ($+7)
02c5:0258 803E500019       cmp  byte [0050],19
02c5:025d 7E06             jle  0265 ($+6)
02c5:025f FF36A83D         push word [3DA8]

02c5:0263 EBDA             jmp  short 023F ($-26)
02c5:0265 E8331B           call 1D9B ($+1b33)
02c5:0268 0BC0             or   ax,ax
02c5:026a 7405             je   0271 ($+5)
02c5:026c 68A83E           push 3EA8
02c5:026f EBCE             jmp  short 023F ($-32)
02c5:0271 A1E64C           mov  ax,[4CE6]
02c5:0274 8B16E44C         mov  dx,[4CE4]
02c5:0278 89169200         mov  [0092],dx
02c5:027c A39400           mov  [0094],ax
02c5:027f 16               push ss
02c5:0280 8D46FA           lea  ax,[bp-06]
dosdebug> 
dosdebug> 

02c5:0283 50               push ax
02c5:0284 16               push ss
02c5:0285 8D46FC           lea  ax,[bp-04]
02c5:0288 50               push ax
02c5:0289 E82D1B           call 1DB9 ($+1b2d)
02c5:028c 83C408           add  sp,0008
02c5:028f C1F808           sar  ax,08
02c5:0292 8BF0             mov  si,ax
02c5:0294 E86306           call 08FA ($+663)
02c5:0297 8BF8             mov  di,ax
02c5:0299 83FF02           cmp  di,0002
02c5:029c 7E13             jle  02B1 ($+13)
02c5:029e 83FE02           cmp  si,0002
02c5:02a1 7E0E             jle  02B1 ($+e)
dosdebug> 
dosdebug> 

02c5:02a3 16               push ss
02c5:02a4 8D46F6           lea  ax,[bp-0A]
02c5:02a7 50               push ax
02c5:02a8 E87F1D           call 202A ($+1d7f)
02c5:02ab 59               pop  cx
02c5:02ac 59               pop  cx
02c5:02ad 0BC2             or   ax,dx
02c5:02af 751F             jne  02D0 ($+1f)
02c5:02b1 C746F60000       mov  word [bp-0A],0000
02c5:02b6 C746F80000       mov  word [bp-08],0000
02c5:02bb 16               push ss
02c5:02bc 8D46F6           lea  ax,[bp-0A]
02c5:02bf 50               push ax
02c5:02c0 E8A81B           call 1E6B ($+1ba8)

02c5:02c3 59               pop  cx
02c5:02c4 59               pop  cx
02c5:02c5 0BC0             or   ax,ax
02c5:02c7 7507             jne  02D0 ($+7)
02c5:02c9 FF36AA3D         push word [3DAA]
02c5:02cd E96FFF           jmp  023F ($-91)
02c5:02d0 C41E1800         les  bx,[0018]
02c5:02d4 268B4714         mov  ax,es:[bx+14]
02c5:02d8 268B5712         mov  dx,es:[bx+12]
02c5:02dc 8956DE           mov  [bp-22],dx
02c5:02df 8946E0           mov  [bp-20],ax
02c5:02e2 C45EDE           les  bx,[bp-22]
dosdebug> 
dosdebug> 

02c5:02e5 268A07           mov  al,es:[bx]
02c5:02e8 8846DD           mov  [bp-23],al
02c5:02eb C746E60000       mov  word [bp-1A],0000
02c5:02f0 C746E80000       mov  word [bp-18],0000
02c5:02f5 EB0C             jmp  short 0303 ($+c)
02c5:02f7 FF46DE           inc  word [bp-22]
02c5:02fa C45EDE           les  bx,[bp-22]
02c5:02fd 268A07           mov  al,es:[bx]
02c5:0300 8846DD           mov  [bp-23],al
02c5:0303 807EDD2E         cmp  byte [bp-23],2E
dosdebug> 
dosdebug> 

02c5:0307 75EE             jne  02F7 ($-12)
02c5:0309 EB0C             jmp  short 0317 ($+c)
02c5:030b FF46DE           inc  word [bp-22]
02c5:030e C45EDE           les  bx,[bp-22]
02c5:0311 268A07           mov  al,es:[bx]
02c5:0314 8846DD           mov  [bp-23],al
02c5:0317 807EDD30         cmp  byte [bp-23],30
02c5:031b 7C06             jl   0323 ($+6)
02c5:031d 807EDD39         cmp  byte [bp-23],39
02c5:0321 7E3E             jle  0361 ($+3e)
02c5:0323 807EDD0D         cmp  byte [bp-23],0D
dosdebug> 
dosdebug> 

02c5:0327 7438             je   0361 ($+38)
02c5:0329 807EDD0A         cmp  byte [bp-23],0A
02c5:032d 75DC             jne  030B ($-24)
02c5:032f EB30             jmp  short 0361 ($+30)
02c5:0331 8B4EE8           mov  cx,[bp-18]
02c5:0334 8B5EE6           mov  bx,[bp-1A]
02c5:0337 33D2             xor  dx,dx
02c5:0339 B80A00           mov  ax,000A
02c5:033c E83839           call 3C77 ($+3938)
02c5:033f 50               push ax
02c5:0340 8A46DD           mov  al,[bp-23]
02c5:0343 98               cbw
02c5:0344 05D0FF           add  ax,FFD0

02c5:0347 52               push dx
02c5:0348 99               cwd
02c5:0349 5B               pop  bx
02c5:034a 59               pop  cx
02c5:034b 03C1             add  ax,cx
02c5:034d 13D3             adc  dx,bx
02c5:034f 8946E6           mov  [bp-1A],ax
02c5:0352 8956E8           mov  [bp-18],dx
02c5:0355 FF46DE           inc  word [bp-22]
02c5:0358 C45EDE           les  bx,[bp-22]
02c5:035b 268A07           mov  al,es:[bx]
02c5:035e 8846DD           mov  [bp-23],al
02c5:0361 807EDD30         cmp  byte [bp-23],30
02c5:0365 7C06             jl   036D ($+6)
dosdebug> 
dosdebug> 

02c5:0367 807EDD39         cmp  byte [bp-23],39
02c5:036b 7EC4             jle  0331 ($-3c)
02c5:036d 8B46E6           mov  ax,[bp-1A]
02c5:0370 0B46E8           or   ax,[bp-18]
02c5:0373 7503             jne  0378 ($+3)
02c5:0375 E99602           jmp  060E ($+296)
02c5:0378 803E673F04       cmp  byte [3F67],04
02c5:037d 7307             jnc  0386 ($+7)
02c5:037f 33D2             xor  dx,dx
02c5:0381 B8F07F           mov  ax,7FF0
02c5:0384 EB06             jmp  short 038C ($+6)
02c5:0386 BA1F00           mov  dx,001F
dosdebug> 
dosdebug> 

02c5:0389 B8E0FD           mov  ax,FDE0
02c5:038c 8946EE           mov  [bp-12],ax
02c5:038f 8956F0           mov  [bp-10],dx
02c5:0392 8B46E8           mov  ax,[bp-18]
02c5:0395 8B56E6           mov  dx,[bp-1A]
02c5:0398 3B46F0           cmp  ax,[bp-10]
02c5:039b 7223             jc   03C0 ($+23)
02c5:039d 7705             ja   03A4 ($+5)
02c5:039f 3B56EE           cmp  dx,[bp-12]
02c5:03a2 761C             jbe  03C0 ($+1c)
02c5:03a4 FF76F0           push word [bp-10]
02c5:03a7 FF76EE           push word [bp-12]
dosdebug> 
dosdebug> 

02c5:03aa FF36AC3D         push word [3DAC]
02c5:03ae E8AD21           call 255E ($+21ad)
02c5:03b1 83C406           add  sp,0006
02c5:03b4 8B46F0           mov  ax,[bp-10]
02c5:03b7 8B56EE           mov  dx,[bp-12]
02c5:03ba 8956E6           mov  [bp-1A],dx
02c5:03bd 8946E8           mov  [bp-18],ax
02c5:03c0 8B56E8           mov  dx,[bp-18]
02c5:03c3 8B46E6           mov  ax,[bp-1A]
02c5:03c6 050F00           add  ax,000F
02c5:03c9 83D200           adc  dx,0000

02c5:03cc B104             mov  cl,04
02c5:03ce E8EF35           call 39C0 ($+35ef)
02c5:03d1 B104             mov  cl,04
02c5:03d3 E8C935           call 399F ($+35c9)
02c5:03d6 8946F2           mov  [bp-0E],ax
02c5:03d9 8956F4           mov  [bp-0C],dx
02c5:03dc 8B46F4           mov  ax,[bp-0C]
02c5:03df 8B56F2           mov  dx,[bp-0E]
02c5:03e2 3B46F8           cmp  ax,[bp-08]
02c5:03e5 721A             jc   0401 ($+1a)
02c5:03e7 7705             ja   03EE ($+5)
02c5:03e9 3B56F6           cmp  dx,[bp-0A]
dosdebug> 
dosdebug> 

02c5:03ec 7613             jbe  0401 ($+13)
02c5:03ee 8B46F8           mov  ax,[bp-08]
02c5:03f1 8B56F6           mov  dx,[bp-0A]
02c5:03f4 8956F2           mov  [bp-0E],dx
02c5:03f7 8946F4           mov  [bp-0C],ax
02c5:03fa 68BE3E           push 3EBE
02c5:03fd E8E523           call 27E5 ($+23e5)
02c5:0400 59               pop  cx
02c5:0401 8B46F8           mov  ax,[bp-08]
02c5:0404 8B56F6           mov  dx,[bp-0A]
02c5:0407 2B56F2           sub  dx,[bp-0E]
02c5:040a 1B46F4           sbb  ax,[bp-0C]
dosdebug> 
dosdebug> 

02c5:040d 8956E2           mov  [bp-1E],dx
02c5:0410 8946E4           mov  [bp-1C],ax
02c5:0413 8B46E2           mov  ax,[bp-1E]
02c5:0416 0B46E4           or   ax,[bp-1C]
02c5:0419 741C             je   0437 ($+1c)
02c5:041b 833E883F00       cmp  word [3F88],0000
02c5:0420 7415             je   0437 ($+15)
02c5:0422 68E04B           push 4BE0
02c5:0425 FF76E4           push word [bp-1C]
02c5:0428 FF76E2           push word [bp-1E]
02c5:042b E82104           call 084F ($+421)
dosdebug> 
dosdebug> 

02c5:042e 83C406           add  sp,0006
02c5:0431 0BC0             or   ax,ax
02c5:0433 7402             je   0437 ($+2)
02c5:0435 EB29             jmp  short 0460 ($+29)
02c5:0437 685200           push 0052
02c5:043a FF76F4           push word [bp-0C]
02c5:043d FF76F2           push word [bp-0E]
02c5:0440 E80C04           call 084F ($+40c)
02c5:0443 83C406           add  sp,0006
02c5:0446 0BC0             or   ax,ax
02c5:0448 741D             je   0467 ($+1d)
02c5:044a 8B46E2           mov  ax,[bp-1E]
02c5:044d 0B46E4           or   ax,[bp-1C]

02c5:0450 740E             je   0460 ($+e)
02c5:0452 833E883F00       cmp  word [3F88],0000
02c5:0457 7407             je   0460 ($+7)
02c5:0459 68E04B           push 4BE0
02c5:045c E87204           call 08D1 ($+472)
02c5:045f 59               pop  cx
02c5:0460 FF36AE3D         push word [3DAE]
02c5:0464 E9D8FD           jmp  023F ($-228)
02c5:0467 8B46E2           mov  ax,[bp-1E]
02c5:046a 0B46E4           or   ax,[bp-1C]
02c5:046d 740E             je   047D ($+e)
02c5:046f 833E883F00       cmp  word [3F88],0000
dosdebug> 
dosdebug> 

02c5:0474 7407             je   047D ($+7)
02c5:0476 68E04B           push 4BE0
02c5:0479 E85504           call 08D1 ($+455)
02c5:047c 59               pop  cx
02c5:047d 8B46F4           mov  ax,[bp-0C]
02c5:0480 8B56F2           mov  dx,[bp-0E]
02c5:0483 D1E2             shl  dx,1
02c5:0485 D1D0             rcl  ax,1
02c5:0487 89164B00         mov  [004B],dx
02c5:048b A34D00           mov  [004D],ax(xmsdsk_magic_word_2)
02c5:048e 833E4D0001       cmp  word [004D],0001
02c5:0493 770E             ja   04A3 ($+e)
dosdebug> 
dosdebug> 

02c5:0495 7207             jc   049E ($+7)
02c5:0497 833E4B0000       cmp  word [004B],0000
02c5:049c 7305             jnc  04A3 ($+5)
02c5:049e A14B00           mov  ax,[004B](xmsdsk_magic_word_1)
02c5:04a1 EB02             jmp  short 04A5 ($+2)
02c5:04a3 33C0             xor  ax,ax
02c5:04a5 A33E00           mov  [003E],ax
02c5:04a8 8B164D00         mov  dx,[004D]
02c5:04ac A14B00           mov  ax,[004B](xmsdsk_magic_word_1)
02c5:04af B105             mov  cl,05
02c5:04b1 E80C35           call 39C0 ($+350c)
02c5:04b4 8946E6           mov  [bp-1A],ax
dosdebug> 
dosdebug> 

02c5:04b7 8956E8           mov  [bp-18],dx
02c5:04ba 837EE800         cmp  word [bp-18],0000
02c5:04be 720E             jc   04CE ($+e)
02c5:04c0 7507             jne  04C9 ($+7)
02c5:04c2 817EE60002       cmp  word [bp-1A],0200
02c5:04c7 7205             jc   04CE ($+5)
02c5:04c9 B80002           mov  ax,0200
02c5:04cc EB09             jmp  short 04D7 ($+9)
02c5:04ce 8B46E6           mov  ax,[bp-1A]
02c5:04d1 051F00           add  ax,001F
02c5:04d4 25E003           and  ax,03E0

02c5:04d7 A33C00           mov  [003C],ax
02c5:04da 833E8A3F00       cmp  word [3F8A],0000
02c5:04df 742F             je   0510 ($+2f)
02c5:04e1 EB04             jmp  short 04E7 ($+4)
02c5:04e3 D0263800         shl  byte [0038],1
02c5:04e7 A03800           mov  al,[0038]
02c5:04ea 98               cbw
02c5:04eb 99               cwd
02c5:04ec 52               push dx
02c5:04ed 50               push ax
02c5:04ee FF364D00         push word [004D]
02c5:04f2 FF364B00         push word [004B]
02c5:04f6 E8FF33           call 38F8 ($+33ff)
dosdebug> 
dosdebug> 

02c5:04f9 8946EA           mov  [bp-16],ax
02c5:04fc 8956EC           mov  [bp-14],dx
02c5:04ff 0BD2             or   dx,dx
02c5:0501 77E0             ja   04E3 ($-20)
02c5:0503 7303             jnc  0508 ($+3)
02c5:0505 E9A700           jmp  05AF ($+a7)
02c5:0508 3DF0FF           cmp  ax,FFF0
02c5:050b 73D6             jnc  04E3 ($-2a)
02c5:050d E99F00           jmp  05AF ($+9f)
02c5:0510 C746E60100       mov  word [bp-1A],0001
02c5:0515 C746E80000       mov  word [bp-18],0000
dosdebug> 
dosdebug> 

02c5:051a C746FE0000       mov  word [bp-02],0000
02c5:051f EB31             jmp  short 0552 ($+31)
02c5:0521 8B56E8           mov  dx,[bp-18]
02c5:0524 8B46E6           mov  ax,[bp-1A]
02c5:0527 8A4EFE           mov  cl,[bp-02]
02c5:052a E87234           call 399F ($+3472)
02c5:052d 52               push dx
02c5:052e 50               push ax
02c5:052f FF364D00         push word [004D]
02c5:0533 FF364B00         push word [004B]
02c5:0537 E8BE33           call 38F8 ($+33be)
dosdebug> 
dosdebug> 

02c5:053a 8946EA           mov  [bp-16],ax
02c5:053d 8956EC           mov  [bp-14],dx
02c5:0540 837EEC00         cmp  word [bp-14],0000
02c5:0544 7709             ja   054F ($+9)
02c5:0546 7210             jc   0558 ($+10)
02c5:0548 817EEAF00F       cmp  word [bp-16],0FF0
02c5:054d 7209             jc   0558 ($+9)
02c5:054f FF46FE           inc  word [bp-02]
02c5:0552 837EFE05         cmp  word [bp-02],0005
02c5:0556 7CC9             jl   0521 ($-37)
02c5:0558 837EEC00         cmp  word [bp-14],0000

The change occurred at 02c5:0487

stsp commented 5 years ago

I suppose we need to compare 2 traces of init now.

andrewbird commented 5 years ago

Yes, but I'm wondering with FreeDOS how to break somewhere between the driver load to memory and calling its init function.

stsp commented 5 years ago

For example by patching driver's code with 0xcc, and when it breaks, replace back by hands. Have you used hiew.exe or qview.exe for patching executables?

andrewbird commented 5 years ago

Have you used hiew.exe or qview.exe for patching executables?

Thanks, but i haven't tried either, so maybe next time as I just got lucky with dosemu/dosdebug's -H9 option. It didn't break exactly where i wanted it, but then clearing and resetting the bp got me to the start of xmsdsk's init. I did have to revert cpu_vm to unset as for some reason I was getting a segfault at startup. But here is the xmsdsk_init_FreeDOS.zip. I'll try to repeat with FDPP.

andrewbird commented 5 years ago

Here's the corresponding one for FDPP xmsdsk_init_FDPP.zip

stsp commented 5 years ago

Please report or debug a segfault.

andrewbird commented 5 years ago

Can you just check out hdr/device.h and the definition / use of _r_cmdline as I notice it's the only use of MK_FAR_STR_OBJ() in the whole of FDPP, please?

      UBYTE _r_nunits;          /*  number of units     */                      
      __DOSFAR(BYTE)_r_endaddr;     /*  Ending Address      */                  
      union {                                                                   
        __DOSFAR(bpb) _r_bpbptr;     /*  ptr to BPB array    */                 
        __DOSFAR(char) _r_cmdline;                                              
      } _r_cmd;                                                                 
      UBYTE _r_firstunit;
stsp commented 5 years ago

Declared as __DOSFAR and the FAR version of macro is used. PTR_MEMB definitions use the NEAR version. But what is the problem? This obj stuff may have the bugs indeed.

andrewbird commented 5 years ago

I'm about to write a dosdebug extension to print the request_header easily, so noticed the difference in the structure between FDPP and my device drivers book / FreeDOS. This C++ stuff is all voodoo so of course I'm suspicious as it's not obviously right to me. I also remember that my emudsk.sys driver doesn't use the command line, but xmsdsk does.

Just looking for patterns...

stsp commented 5 years ago

Did you notice it in a definition, or in the dump? The definition looks fine, __DOSFAR is basically a seg/off far ptr. C++ stuff here is indeed voodoo, and not only for you: even g++ doesn't understand it. Only clang++ can parse that kind of crap (and even then, with lots of work-arounds).

andrewbird commented 5 years ago

Did you notice it in a definition

Yes, I haven't checked it from dosdebug yet, hence writing the nice print function.

Since the cmdline pointer occupies the same storage space with BPB pointer, does it matter to FDPP that block drivers overwrite that pointer value during the init routine so that it points at the drivers BPB?

stsp commented 5 years ago

I hope it doesn't matter much unless someone then uses that pointer as a pointer.

andrewbird commented 5 years ago

I was thinking more in terms of MK_FAR_STR_OBJ() tidy up after use.

stsp commented 5 years ago

There are garbage collectors, so if things work correctly, nothing should go wrong.

andrewbird commented 5 years ago

Is there any way of validating a pointer obtained via FAR2PTR(x) before I dereference it?

stsp commented 5 years ago

It should be valid... What's the problem?

andrewbird commented 5 years ago

Just wondered if it was possible to segfault when dereferencing it, if I need to guard against that?

stsp commented 5 years ago

Nope because FAR ptr is always valid. Therefore the converted flat ptr should be. I believe that the special care is taken to fix up the permissions for the converted ptr, for example far ptr can point to R/O memory, but the converted flat ptr should point to R/W to avoid any segfaults. If not - likely a bug.

stsp commented 5 years ago

We check DPMI far pointers sometimes. Not the case here.

andrewbird commented 5 years ago

So checking the device driver request header with FDPP on xmsdsk init at entry and exit looks okay, although I do wonder why I didn't see the arguments as it was loaded as device=xmsdsk.exe 8000.

dosdebug> usermap load-ms xmsdsk.map 0x02B2
dosdebug> 
reading MSLINK map file 'xmsdsk.map'
symbol table now contains 274 symbol(s)
dosdebug> bp xmsdsk_interrupt
dosdebug> g
dosdebug> 
Warning: code at breakpoint 0 has been overwritten (0x01)
Warning: code at breakpoint 0 has been overwritten (0x9c)
system state: emulated,stopped
AX=00b2  BX=12c9  CX=0000  DX=12ce  SI=0000  DI=03e4  SP=03d6  BP=03de
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000b3206
CS:IP=02b2:00b2       SS:SP=9fbf:03d6

xmsdsk_interrupt:
02b2:00b2 9C               pushf 
dosdebug> d xmsdsk_rh_pointer
dosdebug> 

02b2:0018 C9 12 D9 00 01 02 DE 00 F8 00 07 01 1A 01 DA 00  I.Y...^.x.....Z.
02b2:0028 DA 00 DA 00 16 01 16 01 DA 00 DA 00 DA 00 00 02  Z.Z.....Z.Z.Z...
02b2:0038 01 01 00 01 00 00 00 00 F8 00 00 08 00 01 00 00  ........x.......
02b2:0048 00 00 00 00 00 00 00 90 FF FF 00 00 00 00 00 00  ..............
02b2:0058 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02b2:0068 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02b2:0078 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02b2:0088 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
dosdebug> ddrh 00d9:12c9
dosdebug> 
Request
  length 30
  unit   0
  command 'Init'
    nunits 22
    break 8b46:fff0
    At Entry
      cmdline 00d9:12b8
        => 'C:\XMSDSK.EXE 
'
    At Exit
      BPB 00d9:12b8
    first_drive 6
  status 0x0000

dosdebug> bp xmsdsk_interrupt_return
dosdebug> g

dosdebug> 
system state: emulated,stopped
AX=00b2  BX=12c9  CX=0000  DX=12ce  SI=0000  DI=03e4  SP=03d6  BP=03de
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000b3206
CS:IP=02b2:00d9       SS:SP=9fbf:03d6

02b2:00d9 CB               retf
dosdebug> ddrh 00d9:12c9
dosdebug> 
Request
  length 30
  unit   0
  command 'Init'
    nunits 1
    break 02b2:0201
    At Entry
      cmdline 02b2:3db4
        => '6'
    At Exit
      BPB 02b2:3db4
    first_drive 6
  status 0x0100

Edited: BPB is FAR pointer to NEAR pointer (0036) so it's okay.

dosdebug> d 02b2:3db4
dosdebug> 

02b2:3db4 36 00 EB FE 90 46 2E 55 42 45 52 54 4F 00 46 41  6.k~.F.UBERTO.FA
02b2:3dc4 54 20 20 20 20 20 00 4D 53 2D 52 41 4D 44 52 49  T     .MS-RAMDRI
02b2:3dd4 56 45 00 44 4F 53 20 76 65 72 73 69 6F 6E 20 6E  VE.DOS version n
02b2:3de4 6F 74 20 73 75 70 70 6F 72 74 65 64 2E 00 49 6E  ot supported..In
02b2:3df4 76 61 6C 69 64 20 64 72 69 76 65 20 28 69 6E 63  valid drive (inc
02b2:3e04 72 65 61 73 65 20 4C 41 53 54 44 52 49 56 45 20  rease LASTDRIVE 
02b2:3e14 3F 29 2E 00 58 4D 53 20 67 65 74 20 66 72 65 65  ?)..XMS get free
02b2:3e24 20 6D 65 6D 20 65 72 72 6F 72 2E 00 4F 6E 6C 79   mem error..Only

Proceeding to Media Check shows it fails, presumably every time 

dosdebug> d xmsdsk_rh_pointer
dosdebug> 

02b2:0018 7C 03 D9 00 01 02 DE 00 F8 00 07 01 1A 01 DA 00  |.Y...^.x.....Z.
02b2:0028 DA 00 DA 00 16 01 16 01 DA 00 DA 00 DA 00 00 02  Z.Z.....Z.Z.Z...
02b2:0038 01 01 00 01 00 00 00 00 F8 00 00 08 00 01 00 00  ........x.......
02b2:0048 00 00 00 00 00 00 00 90 06 FF 00 00 00 00 00 00  ...............
02b2:0058 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02b2:0068 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02b2:0078 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02b2:0088 00 00 00 00 00 00 00 00 00 00 17 F5 00 F0 00 00  ...........u.p..
dosdebug> ddrh 00d9:037c
dosdebug> 
Request
  length 30
  unit   0
  command 'Media Check'
    media id 0x00
    status 0
  status 0x0000
dosdebug> g
dosdebug> 
system state: emulated,stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08f0  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000b3206
CS:IP=02b2:00d9       SS:SP=00d9:08f0

02b2:00d9 CB               retf
dosdebug> ddrh 00d9:037c
dosdebug> 
Request
  length 30
  unit   0
  command 'Media Check'
    media id 0x00
    status -1
  status 0x8101
dosdebug> g

Will try to repeat with FreeDOS 1.20

andrewbird commented 5 years ago

So it seems like we are losing the command line args and xmsdsk is not reacting well to that..

system state: emulated,stopped
AX=00b2  BX=2356  CX=0000  DX=1130  SI=0000  DI=0008  SP=2342  BP=234a
DS=02c5  ES=9dc0  FS=0000  GS=0000  FL=000b3202
CS:IP=02c5:00b2       SS:SP=9dc0:2342

xmsdsk_interrupt:
02c5:00b2 9C               pushf 
dosdebug> d xmsdsk_rh_pointer
dosdebug> 

02c5:0018 56 23 C0 9D 01 02 DE 00 F8 00 07 01 1A 01 DA 00  V#@...^.x.....Z.
02c5:0028 DA 00 DA 00 16 01 16 01 DA 00 DA 00 DA 00 00 02  Z.Z.....Z.Z.Z...
02c5:0038 01 01 00 01 00 00 00 00 F8 00 00 08 00 01 00 00  ........x.......
02c5:0048 00 00 00 00 00 00 00 90 FF FF 00 00 00 00 00 00  ..............
02c5:0058 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0068 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0078 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0088 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
dosdebug> ddrh 9dc0:2356
dosdebug> 
Request
  length 30
  unit   0
  command 'Init'
    nunits 0
    break 7c66:fff0
    At Entry
      cmdline 9dc0:1126
        => 'XMSDSK.EXE 8000 
'
    At Exit
      BPB 9dc0:1126
    first_drive 6
  status 0x0000
dosdebug> g
dosdebug> 
system state: emulated,stopped
AX=00b2  BX=2356  CX=0000  DX=1130  SI=0000  DI=0008  SP=2342  BP=234a
DS=02c5  ES=9dc0  FS=0000  GS=0000  FL=000b3202
CS:IP=02c5:00d9       SS:SP=9dc0:2342

xmsdsk_interrupt_return:
02c5:00d9 CB               retf
dosdebug> ddrh 9dc0:2356
dosdebug> 
Request
  length 30
  unit   0
  command 'Init'
    nunits 1
    break 02c5:0201
    At Entry
      cmdline 02c5:3db4
        => '6'
    At Exit
      BPB 02c5:3db4
    first_drive 6
  status 0x0100

BPB pointer is 

dosdebug> d 02c5:3db4
dosdebug> 

02c5:3db4 36 00 EB FE 90 46 2E 55 42 45 52 54 4F 00 46 41  6.k~.F.UBERTO.FA
02c5:3dc4 54 20 20 20 20 20 00 4D 53 2D 52 41 4D 44 52 49  T     .MS-RAMDRI
02c5:3dd4 56 45 00 44 4F 53 20 76 65 72 73 69 6F 6E 20 6E  VE.DOS version n
02c5:3de4 6F 74 20 73 75 70 70 6F 72 74 65 64 2E 00 49 6E  ot supported..In
02c5:3df4 76 61 6C 69 64 20 64 72 69 76 65 20 28 69 6E 63  valid drive (inc
02c5:3e04 72 65 61 73 65 20 4C 41 53 54 44 52 49 56 45 20  rease LASTDRIVE 
02c5:3e14 3F 29 2E 00 58 4D 53 20 67 65 74 20 66 72 65 65  ?)..XMS get free
02c5:3e24 20 6D 65 6D 20 65 72 72 6F 72 2E 00 4F 6E 6C 79   mem error..Only

and dereferenced as NEAR we see BPB

dosdebug> d 02c5:0036
dosdebug> 

02c5:0036 00 02 04 01 00 01 00 02 80 3E F8 0C 00 08 00 01  .........>x.....
02c5:0046 00 00 00 00 00 80 3E 00 00 90 06 FF 01 00 00 00  ......>........
02c5:0056 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0066 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0076 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0086 00 00 00 00 00 00 00 00 00 00 00 00 17 F5 00 F0  .............u.p
02c5:0096 00 02 00 00 00 00 DE 49 C5 02 01 00 00 58 00 00  ......^IE....X..
02c5:00a6 2E 89 1E 18 00 2E 8C 06 1A 00 CB 90 9C 60 1E 06  ..........K..`..
dosdebug> g
dosdebug> 
system state: emulated,stopped
AX=00b2  BX=037c  CX=02e7  DX=02e7  SI=0000  DI=02e7  SP=0888  BP=0890
DS=02c5  ES=00d8  FS=0000  GS=0000  FL=000b3297
CS:IP=02c5:00b2       SS:SP=00d8:0888

xmsdsk_interrupt:
02c5:00b2 9C               pushf 
dosdebug> d xmsdsk_rh_pointer
dosdebug> 

02c5:0018 7C 03 D8 00 01 02 DE 00 F8 00 07 01 1A 01 DA 00  |.X...^.x.....Z.
02c5:0028 DA 00 DA 00 16 01 16 01 DA 00 DA 00 DA 00 00 02  Z.Z.....Z.Z.Z...
02c5:0038 04 01 00 01 00 02 80 3E F8 0C 00 08 00 01 00 00  .......>x.......
02c5:0048 00 00 00 80 3E 00 00 90 06 FF 01 00 00 00 00 00  ....>..........
02c5:0058 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0068 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0078 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0088 00 00 00 00 00 00 00 00 00 00 17 F5 00 F0 00 02  ...........u.p..
dosdebug> ddrh 00d8:037c
dosdebug> 
Request
  length 30
  unit   0
  command 'Media Check'
    media id 0x00
    status -80
  status 0x0000
dosdebug> g
dosdebug> 
system state: emulated,stopped
AX=00b2  BX=037c  CX=02e7  DX=02e7  SI=0000  DI=02e7  SP=0888  BP=0890
DS=02c5  ES=00d8  FS=0000  GS=0000  FL=000b3297
CS:IP=02c5:00d9       SS:SP=00d8:0888

xmsdsk_interrupt_return:
02c5:00d9 CB               retf
dosdebug> ddrh 00d8:037c
dosdebug> 
Request
  length 30
  unit   0
  command 'Media Check'
    media id 0x00
    status -1
  status 0x0100
xmsdsk_interrupt:
02c5:00b2 9C               pushf 
dosdebug> d xmsdsk_rh_pointer
dosdebug> 

02c5:0018 7C 03 D8 00 01 02 DE 00 F8 00 07 01 1A 01 DA 00  |.X...^.x.....Z.
02c5:0028 DA 00 DA 00 16 01 16 01 DA 00 DA 00 DA 00 00 02  Z.Z.....Z.Z.Z...
02c5:0038 04 01 00 01 00 02 80 3E F8 0C 00 08 00 01 00 00  .......>x.......
02c5:0048 00 00 00 80 3E 00 00 90 06 FF 01 00 00 00 00 00  ....>..........
02c5:0058 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0068 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0078 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0088 00 00 00 00 00 00 00 00 00 00 17 F5 00 F0 00 02  ...........u.p..
dosdebug> ddrh 00d8:037c
dosdebug> 
Request
  length 30
  unit   0
  command 'Get BPB'
    media id 0x00
    buffer 00d8:0ab0
    BPB 00d8:1aa8
  status 0x0000
dosdebug> g
dosdebug> 
system state: emulated,stopped
AX=00b2  BX=037c  CX=02e7  DX=ffff  SI=0000  DI=02e7  SP=0888  BP=0890
DS=02c5  ES=00d8  FS=0000  GS=0000  FL=000b3246
CS:IP=02c5:00d9       SS:SP=00d8:0888

xmsdsk_interrupt_return:
02c5:00d9 CB               retf
dosdebug> ddrh 00d8:037c
dosdebug> 
Request
  length 30
  unit   0
  command 'Get BPB'
    media id 0x00
    buffer 00d8:0ab0
    BPB 02c5:0036
  status 0x0100
dosdebug> d 02c5:0036
dosdebug> 

02c5:0036 00 02 04 01 00 01 00 02 80 3E F8 0C 00 08 00 01  .........>x.....
02c5:0046 00 00 00 00 00 80 3E 00 00 90 06 01 01 00 00 00  ......>.........
02c5:0056 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0066 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0076 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02c5:0086 00 00 00 00 00 00 00 00 00 00 00 00 17 F5 00 F0  .............u.p
02c5:0096 00 02 00 00 00 00 DE 49 C5 02 01 00 00 58 00 00  ......^IE....X..
02c5:00a6 2E 89 1E 18 00 2E 8C 06 1A 00 CB 90 9C 60 1E 06  ..........K..`..
andrewbird commented 5 years ago

Looks like this fragment looses the arguments config.cc

1953      GetStringArg(pLine, szBuf + off);
(gdb) p pLine
$2 = 0xb72b1b57 <szLine+7> "dosemu\\emufs.sys /tmp"
(gdb) next
1957      eb.load.reloc = eb.load.load_seg = base;
(gdb) p szBuf
$3 = "C:\\dosemu\\emufs.sys", '\000' <repeats 236 times>
andrewbird commented 5 years ago

I think this commit ab57fb0fa3d01d788c278996874731734fe5e98c removed the rest of the arguments

andrewbird commented 5 years ago

Adding this back in made it work for me, but not sure if it matters that the arg0 no longer is fixed up with the boot drive.

diff --git a/kernel/config.c b/kernel/config.c
index 96f4a80..2d77b38 100644
--- a/kernel/config.c
+++ b/kernel/config.c
@@ -1966,6 +1966,7 @@ STATIC BOOL LoadDevice(char * pLine, char FAR *top, COUNT mode)
     return result;
   }

+  strcpy(szBuf, pLine);
   /* uppercase the device driver command */
   _strupr(szBuf);

xmsdsk-okay

andrewbird commented 5 years ago

With commit in #90 here's the transcript

xmsdsk_interrupt:
02b2:00b2 9C               pushf 
dosdebug> d xmsdsk_rh_pointer
dosdebug> 

02b2:0018 CB 12 D9 00 01 02 DE 00 F8 00 07 01 1A 01 DA 00  K.Y...^.x.....Z.
02b2:0028 DA 00 DA 00 16 01 16 01 DA 00 DA 00 DA 00 00 02  Z.Z.....Z.Z.Z...
02b2:0038 01 01 00 01 00 00 00 00 F8 00 00 08 00 01 00 00  ........x.......
02b2:0048 00 00 00 00 00 00 00 90 FF FF 00 00 00 00 00 00  ..............
02b2:0058 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02b2:0068 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02b2:0078 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02b2:0088 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
dosdebug> ddrh 00d9:12cb
dosdebug> 
Request
  length 30
  unit   0
  command 'Init'
    nunits 246
    break 8b46:fff0
    At Entry
      cmdline 00d9:12b8
        => 'XMSDSK.EXE 8000 
'
    At Exit
      BPB 00d9:12b8
    first_drive 6
  status 0x0000
dosdebug> g
dosdebug> 
system state: emulated,stopped
AX=00b2  BX=12cb  CX=0000  DX=12ce  SI=0000  DI=03e4  SP=03d6  BP=03de
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000b3206
CS:IP=02b2:00d9       SS:SP=9fbf:03d6

xmsdsk_interrupt_return:
02b2:00d9 CB               retf
dosdebug> ddrh 00d9:12cb
dosdebug> 
Request
  length 30
  unit   0
  command 'Init'
    nunits 1
    break 02b2:0201
    At Entry
      cmdline 02b2:3db4
        => '6'
    At Exit
      BPB 02b2:3db4
    first_drive 6
  status 0x0100
xmsdsk_interrupt:
02b2:00b2 9C               pushf 
dosdebug> d xmsdsk_rh_pointer
dosdebug> 

02b2:0018 7C 03 D9 00 01 02 DE 00 F8 00 07 01 1A 01 DA 00  |.Y...^.x.....Z.
02b2:0028 DA 00 DA 00 16 01 16 01 DA 00 DA 00 DA 00 00 02  Z.Z.....Z.Z.Z...
02b2:0038 04 01 00 01 00 02 80 3E F8 0C 00 08 00 01 00 00  .......>x.......
02b2:0048 00 00 00 80 3E 00 00 90 06 FF 01 00 00 00 00 00  ....>..........
02b2:0058 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02b2:0068 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02b2:0078 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
02b2:0088 00 00 00 00 00 00 00 00 00 00 17 F5 00 F0 00 02  ...........u.p..
dosdebug> ddrh 00d9:037c
dosdebug> 
Request
  length 30
  unit   0
  command 'Media Check'
    media id 0x00
    status 0
  status 0x0000
dosdebug> g
dosdebug> 
system state: emulated,stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08f0  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000b3206
CS:IP=02b2:00d9       SS:SP=00d9:08f0

xmsdsk_interrupt_return:
02b2:00d9 CB               retf
dosdebug> ddrh 00d9:037c
dosdebug> 
Request
  length 30
  unit   0
  command 'Media Check'
    media id 0x00
    status -1
  status 0x0100
xmsdsk_interrupt:
02b2:00b2 9C               pushf 
dosdebug> ddrh 00d9:037c
dosdebug> 
Request
  length 30
  unit   0
  command 'Get BPB'
    media id 0x00
    buffer 02d9:0000
    BPB 00d9:1966
  status 0x0000
dosdebug> g
dosdebug> 
system state: emulated,stopped
AX=00b2  BX=037c  CX=0000  DX=091c  SI=0000  DI=08fe  SP=08f0  BP=08f8
DS=02b2  ES=00d9  FS=0000  GS=0000  FL=000b3206
CS:IP=02b2:00d9       SS:SP=00d9:08f0

xmsdsk_interrupt_return:
02b2:00d9 CB               retf
dosdebug> ddrh 00d9:037c
dosdebug> 
Request
  length 30
  unit   0
  command 'Get BPB'
    media id 0x00
    buffer 02d9:0000
    BPB 02b2:0036
  status 0x0100