Note this is not necessarily a bug in the emulator itself, but it's a crash that can potentially be fixed emulator-side. This issue is intended to discuss an appropriate fix before a PR is prepared.
When a game switches ELFs using LoadExecPS2 with 128MB RAM mode enabled, the emulator may crash if the user has an older BIOS version. This is because some older BIOS versions do not have an entry for syscall 0x82 (_InitTLB)*. When the userland InitTLB function is run, it branches on the result of GetMemorySize(), calling InitTLB32MB when it is 0x2000000 or invoking the _InitTLB syscall otherwise.
* Despite _InitTLB not being present in the syscall table, the function itself does seem to exist within the BIOS.
This issue is currently confirmed to occur with BIOS 1.60, but it presumably occurs in all prior versions too. It is not yet known if any later versions exhibit the problem.
After determining affected BIOS versions or finding a way to tell if the _InitTLB syscall is missing, possible solutions could be:
HLE emulate the _InitTLB syscall on affected BIOS versions.
This seems like the most appropriate solution to me, though I'm not sure of the specifics of what _InitTLB does.
Don't intercept the GetMemorySize syscall for affected BIOS versions.
Not an ideal solution, but it would force games to still use InitTLB32MB instead of the BIOS implementation.
Display an additional startup warning when 128MB mode is used with an affected BIOS version.
Disable or disallow 128MB mode for affected BIOS versions.
Describe the Bug
Note this is not necessarily a bug in the emulator itself, but it's a crash that can potentially be fixed emulator-side. This issue is intended to discuss an appropriate fix before a PR is prepared.
When a game switches ELFs using
LoadExecPS2with 128MB RAM mode enabled, the emulator may crash if the user has an older BIOS version. This is because some older BIOS versions do not have an entry for syscall0x82(_InitTLB)*. When the userlandInitTLBfunction is run, it branches on the result ofGetMemorySize(), callingInitTLB32MBwhen it is0x2000000or invoking the_InitTLBsyscall otherwise.* Despite
_InitTLBnot being present in the syscall table, the function itself does seem to exist within the BIOS.This issue is currently confirmed to occur with BIOS 1.60, but it presumably occurs in all prior versions too. It is not yet known if any later versions exhibit the problem.
After determining affected BIOS versions or finding a way to tell if the
_InitTLBsyscall is missing, possible solutions could be:_InitTLBsyscall on affected BIOS versions._InitTLBdoes.GetMemorySizesyscall for affected BIOS versions.InitTLB32MBinstead of the BIOS implementation.Reproduction Steps
Option 1
Option 2
main.elf(withload.elfnext to it) from the samples provided in https://github.com/PCSX2/pcsx2/pull/11195.Expected Behavior
No response
PCSX2 Revision
v1.7.5801
Operating System
Windows 11
If Linux - Specify Distro
No response
CPU
Ryzen 9 3900X
GPU
GTX 2080 Super
GS Settings
No response
Emulation Settings
No response
GS Window Screenshots
No response
Logs & Dumps
No response