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The Open SIMH simulators package
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imlac crashes during :imprint on ITS #216

Closed bilegeek closed 1 year ago

bilegeek commented 1 year ago

This is a bit long-winded, since reproducing the error requires building the ITS simulator and navigating the OS, so I've just listed some step-by-step stuff. I'm also running Linux. Please excuse how convoluted it is.

The ITS repo actually clones this repo and builds the imlac emulator as part of making the entire simulator, but I decided to manually clone and build it from here.

make sure dependencies are installed (git, c compiler, make, expect, curses, autoconf, sdl2, sdl2-image, sdl2-net, gtk3)

git clone https://github.com/PDP-10/its/ cd its make EMULATOR=pdp10-ka

Takes awhile to build. Like 3-4 hours in my case. Mainly because the simulator is ALSO building ITS from source. So it's slow.

Once it finishes, ./start (Wait until it shows DSKDMP) its (press enter, then escape-G, wait a bit, then ctrl-Z)

git clone https://github.com/open-simh/simh/ cd simh make imlac

(press ctrl-Z; should say "Happy hacking!") :login turist :cwd -pics- (ctrl-F to list directory, ctrl-L to clear screen)
:imprint 10 pic

:imprint 3d pic

:imprint trek pic

When the imlac crashes and you restart it with ./tools/sim-h/BIN/./imlac ./build/pdp10-ka/imlac.simh, you'll already be logged in.

When you're done, :logout on the Imlac then :lock, 5down, y, and ctrl-C on the ITS emulator console terminal.

sim> SHOW VERSION Imlac simulator Open SIMH V4.1-0 Current Simulator Framework Capabilities: 32b data 32b addresses no Ethernet Idle/Throttling support is available Virtual Hard Disk (VHD) support RAW disk and CD/DVD ROM support Asynchronous I/O support (Lock free asynchronous event queue) Asynchronous Clock support FrontPanel API Version 12 Host Platform: Compiler: GCC 10.2.1 20210110 Simulator Compiled as C arch: x64 (Release Build) on Apr 12 2023 at 23:20:24 Build Tool: simh-makefile Memory Access: Little Endian Memory Pointer Size: 64 bits Large File (>2GB) support SDL Video support: SDL Version 2.0.14, PNG Version 1.6.37, zlib: 1.2.11 PCRE RegEx (Version 8.39 2016-06-14) support for EXPECT commands OS clock resolution: 1ms Time taken by msleep(1): 1ms OS: Linux reliable 5.10.0-21-amd64 #1 SMP Debian 5.10.162-1 (2023-01-21) x86_64 GNU/Linux Processor Name: AMD FX(tm)-8350 Eight-Core Processor tar tool: tar (GNU tar) 1.34 curl tool: curl 7.74.0 (x86_64-pc-linux-gnu) libcurl/7.74.0 OpenSSL/1.1.1n zlib/1.2.11 brotli/1.0.9 libidn2/2.3.0 libpsl/0.21.0 (+libidn2/2.3.0) libssh2/1.9.0 nghttp2/1.43.0 librtmp/2.3 git commit id: 7be9f2f3 git commit time: 2023-04-09T10:36:40-0700

Make output:

lib paths are: /lib/ /lib/i386-linux-gnu/ /lib/i386-linux-gnu/i686/sse2/ /lib/i386-linux-gnu/sse2/ /lib/x86_64-linux-gnu/ /lib32/ /libx32/ /usr/lib/x86_64-linux-gnu/libfakeroot/ /usr/lib/ include paths are: /usr/lib/gcc/x86_64-linux-gnu/10/include /usr/local/include /usr/include/x86_64-linux-gnu /usr/include using libm: /lib/x86_64-linux-gnu/libm.so using librt: /lib/x86_64-linux-gnu/librt.so using libpthread: /lib/x86_64-linux-gnu/libpthread.so /usr/include/pthread.h using libpcre: /lib/x86_64-linux-gnu/libpcre.so /usr/include/pcre.h using semaphore: /usr/include/semaphore.h using libdl: /lib/x86_64-linux-gnu/libdl.so /usr/include/dlfcn.h using libpng: /lib/x86_64-linux-gnu/libpng.so /usr/include/png.h using zlib: /lib/x86_64-linux-gnu/libz.so /usr/include/zlib.h using mman: /usr/include/x86_64-linux-gnu/sys/mman.h using libSDL2: /usr/include/SDL2/SDL.h *** No SDL ttf support available. BESM-6 video panel disabled.

Info Install the development components of libSDL2-ttf Info packaged for your Linux operating system distribution: Info $ sudo apt-get install libsdl2-ttf-dev

imlac Simulator being built with: - compiler optimizations and no debugging support. GCC Version: 10.2.1. - video capabilities provided by libSDL2 (Simple Directmedia Layer). - Per simulator tests will be run.

git commit id is 7be9f2f3e86ebd05daff7697c0758f71dc8c27d3. git commit time is 2023-04-09T10:36:40-0700.

gcc -std=gnu99 -U__STRICT_ANSI__ -O2 -finline-functions -fgcse-after-reload -fpredictive-commoning -fipa-cp-clone -fno-unsafe-loop-optimizations -fno-strict-overflow -DSIM_GIT_COMMIT_ID=7be9f2f3e86ebd05daff7697c0758f71dc8c27d3 -DSIM_GIT_COMMIT_TIME=2023-04-09T10:36:40-0700 -DSIM_COMPILER="GCC Version: 10.2.1" -DSIM_BUILD_TOOL=simh-makefile -I . -Werror -D_GNU_SOURCE -DUSE_READER_THREAD -DSIM_ASYNCH_IO -DHAVE_PCRE_H -DHAVE_SEMAPHORE -DHAVE_SYS_IOCTL -DHAVE_LINUX_CDROM -DSIM_HAVE_DLOPEN=so -DHAVE_UTIME -DHAVE_LIBPNG -DHAVE_ZLIB -DHAVE_GLOB -DHAVE_SHM_OPEN ./imlac/imlac_sys.c ./imlac/imlac_cpu.c ./imlac/imlac_dp.c ./imlac/imlac_crt.c ./imlac/imlac_kbd.c ./imlac/imlac_tty.c ./imlac/imlac_pt.c ./imlac/imlac_bel.c ./display/display.c ./display/sim_ws.c ./scp.c ./sim_console.c ./sim_fio.c ./sim_timer.c ./sim_sock.c ./sim_tmxr.c ./sim_ether.c ./sim_tape.c ./sim_disk.c ./sim_serial.c ./sim_video.c ./sim_imd.c ./sim_card.c -I ./imlac -DUSE_DISPLAY -DHAVE_LIBSDL -DUSE_SIM_VIDEO sdl2-config --cflags sdl2-config --libs -o BIN/imlac -lm -lrt -lpthread -lpcre -ldl -lpng -lz
BIN/imlac RegisterSanityCheck </dev/null Running internal register sanity checks on Imlac simulator. *** Good Registers in Imlac simulator.

larsbrinkhoff commented 1 year ago

Please assign this to me.

larsbrinkhoff commented 1 year ago

At a first glance, this seems to be a bug in the Imlac software, not the emulator. The crash happens when an interrupt is handled. The interrupt handler is at location 1 in memory. The code there has been clobbered due to a buffer wrapping around the top of memory to low memory. Maybe the input file (I used 3D PIC) is too large to fit in the buffer used to hold the display list, and the program doesn't check the upper bound.

bilegeek commented 1 year ago

Some observations:

I've just tested every file in -pics- sorted by filesize (aside from "pics xfile" and "-read- -this-", as they're just regular text), and it seems more complicated than that. For instance, "numbur pic" crashes, but the larger file "girl pic" doesn't.

List of the files that crashed on me: numbur pic, a plot, pyram pic, world pic, 3d pic, mit1 pic, trek pic, kana pic, phx pic

The ellips, dragon and chain pics all work, and they're sandwiched between 3d and mit1. Wumpus doesn't crash, but does glitch out after a brief second of drawing correctly.

Every crash, same error: "HALT instruction, PC: 00013 (HLT )" (odd, 3d pic gave me the location 1 error last time)

"[pic] 42" is interesting: it locks - but doesn't seem to crash - the imlac after drawing a cube, but when I restart the imlac and Ctrl-F, it draws a spiral torus.

Every other file aside from those listed as crashy seem to work fine.

larsbrinkhoff commented 1 year ago

Thanks for checking! I'm not sure my initial impression is the right one; I'll have to check further. I think making some test cases that probe the boundaries will be enlightening.

larsbrinkhoff commented 1 year ago

I just tested @jdersch's sImlac, and viewing 3D PIC behaves the same - crashing in the same place, as far as I can see. So I'm leaning towards believing the emulator works as intended, and the problem is in the SSV software. But I would still like to do some tests to see the exact cause, so let's keep this open for now.

larsbrinkhoff commented 1 year ago

More information. I truncated the 3D PIC file to the first 5000 characters. The truncated file prints fine. but the display says CBUF=25. Pressing space reduces the CBUF number. When it reaches 0, the crash happens.

Moreover, from what I can read in the code, it's trying to free upp buffer space by scrolling ten lines. The problem in this case is that there is just one super long file. This case is not anticipated, so it fails.

larsbrinkhoff commented 1 year ago

So far there is no evidence of any bug in the emulator, so I think this issue can be closed.