Daniel, if you manage to reproduce on clean develop, please also open an issue at https://gem5.atlassian.net/jira/software/c/projects/GEM5/issues I'd also be curious to see if it reproduces on se.py (so I could see if it also happens on ARM).
We've had some ARM-specific SE issues e.g. at https://gem5.atlassian.net/browse/GEM5-537 but this is X86 so I'm not sure. With SyscallAll + ExecAll and some patience most bugs can be found. Presumably new instructions are being run in an infinite loop, otherwise simulation would reach the end of time. So I would try to determine what that minimal loop is and why it won't exit. ________________________________ From: Daniel Gerzhoy via gem5-users <gem5-users@gem5.org> Sent: Wednesday, October 28, 2020 7:21 PM To: gem5 users mailing list <gem5-users@gem5.org> Cc: Daniel Gerzhoy <daniel.gerz...@gmail.com> Subject: [gem5-users] Re: SE Mode and Std::thread Looks like this is related to this change: https://gem5-review.googlesource.com/c/public/gem5/+/8184 I'm a bit behind develop because of custom changes and don't have this patch merged yet. Cherry picking this might work, but merging would probably be the best solution, if time consuming. Cheers, Dan On Tue, Oct 27, 2020 at 3:39 PM Daniel Gerzhoy <daniel.gerz...@gmail.com<mailto:daniel.gerz...@gmail.com>> wrote: Hey all, I'm running into a strange issue where threads are not spawning when launched with std::thread. It seems to work once, and then I try to launch again using a newly allocated thread pointer (after deleting the old one) and it hangs. Minimal example: void foo() { printf("Foo alive from tid %lu\n", m5_cpu_id()); //m5_cpu_id is a pseudo_instruction I added to return tc->cpuId() } void main() { printf("Launching foo 1"\n); std::thread * mythread = new std::thread(foo,...); printf("Done Launching foo 1"\n); printf("Joining foo 1"\n); myThread->join(); delete myThread; printf("Launching foo 2"\n); mythread = new std::thread(foo,...); printf("Done Launching foo 2"\n); printf("Joining foo 2"\n); myThread->join(); //<<<<< IT HANGS HERE printf("Done Everything!\n"); delete myThread; } ______ It works fine with TimingSimpleCPU, but then with DerivO3CPU I get the failure. Output for DerivO3CPU: Launch 1 Done Launch 1 I'm alive on tid 1 Launch 2 Done Launch 2 And there it Hangs. FYI I am using apu_se.py, though with the above minimal example I've managed to reproduce the bug with no GPU code (nor even hipcc) involved. I went back to the original code I found that showed std::thread could be used here: https://www.gem5.org/documentation/learning_gem5/part3/running/ [image.png] The comment there that -1 is required for SE mode, and then the subsequent comment about appeasing SE mode... What exactly do those comments mean? I'm going to keep debugging, but if anyone has any suggestions for debug flags that could be helpful it would be appreciated. (I'm using SyscallAll and going to investigate some of the syscalls SE mode ignores). I'm wondering if maybe it is calling join() multiple times that might be the problem? Though unsure why at this point. Thanks! Dan
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