Richard Henderson <richard.hender...@linaro.org> writes: > It is my guess that the majority of the flakiness with the > linux-user signals.c test is due to a race condition between > translation and page writes. I vaguely recall a bug report > about this, but I cannot find it now. > > Since the vast majority of "self-modifying code" is due to > signal delivery, work around this by allocating a new page, > into which we write the signal handlers. > > A better workaround would be to implement the vdso that is > required by many guests. However, that is a much larger > problem, and some guests do not define a vdso in upstream > linux. This serves as a decent fallback. > > Neither bit of work, I will note, solves the posited race > condition described above.
Well this certainly solves the failures I was seeing with s390x-on-s390x: retry.py -n 500 -c -- ./qemu-s390x ./tests/tcg/s390x-linux-user/signals Results summary: 0: 500 times (100.00%), avg time 2.253 (0.00 varience/0.00 deviation) Ran command 500 times, 500 passes However qemu-hppa (on x86_64 host) still has the stuborn 1% failure rate (-static build): Results summary: 0: 198 times (99.00%), avg time 2.255 (0.00 varience/0.00 deviation) -4: 2 times (1.00%), avg time 0.252 (0.00 varience/0.00 deviation) Ran command 200 times, 198 passes So have a: Tested-by: Alex Bennée <alex.ben...@linaro.org> (for s390x at least) -- Alex Bennée
