backport arm64 fixes for msys2-3_3_6-release #235
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https://cygwin.com/pipermail/cygwin/2024-February/255397.html reports a crash on ARM64 probably related to checking x86_64 code on the x86_64 emulator on AArch64. At least for testing, pull the code checking the host HW up to be called before trying to evaluate assembler code. Signed-off-by: Corinna Vinschen <[email protected]>
This addresses an extremely difficult to debug deadlock when running under emulation on ARM64. A relatively easy way to trigger this bug is to call `fork()`, then within the child process immediately call another `fork()` and then `exit()` the intermediate process. It would seem that there is a "code emulation" lock on the wait thread at this stage, and if the thread is terminated too early, that lock still exists albeit without a thread, and nothing moves forward. It seems that a `SuspendThread()` combined with a `GetThreadContext()` (to force the thread to _actually_ be suspended, for more details see https://devblogs.microsoft.com/oldnewthing/20150205-00/?p=44743) makes sure the thread is "booted" from emulation before it is suspended. Hopefully this means it won't be holding any locks or otherwise leave emulation in a bad state when the thread is terminated. Also, attempt to use `CancelSynchonousIo()` (as seen in `flock.cc`) to avoid the need for `TerminateThread()` altogether. This doesn't always work, however, so was not a complete fix for the deadlock issue. Addresses: https://cygwin.com/pipermail/cygwin-developers/2024-May/012694.html Signed-off-by: Jeremy Drake <[email protected]>
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I don't use msys2-runtime-3.4, and don't see any use case for it on arm64, so I haven't tried to backport anything to it. |
lazka
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Nov 13, 2024
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Does this also need #236? |
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yes. I was waiting for confirmation that it fixed the issue. |
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Since I already did this for testing on Windows 10 ARM64, I thought I'd open a PR for these too. This is effectively #233 and #234