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authorChristian Krinitsin <mail@krinitsin.com>2025-06-16 16:59:00 +0000
committerChristian Krinitsin <mail@krinitsin.com>2025-06-16 16:59:33 +0000
commit9aba81d8eb048db908c94a3c40c25a5fde0caee6 (patch)
treeb765e7fb5e9a3c2143c68b0414e0055adb70e785 /results/classifier/118/debug/1361
parentb89a938452613061c0f1f23e710281cf5c83cb29 (diff)
downloademulator-bug-study-9aba81d8eb048db908c94a3c40c25a5fde0caee6.tar.gz
emulator-bug-study-9aba81d8eb048db908c94a3c40c25a5fde0caee6.zip
add 18th iteration of classifier
Diffstat (limited to 'results/classifier/118/debug/1361')
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1 files changed, 50 insertions, 0 deletions
diff --git a/results/classifier/118/debug/1361 b/results/classifier/118/debug/1361
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@@ -0,0 +1,50 @@
+debug: 0.930
+graphic: 0.882
+vnc: 0.881
+ppc: 0.862
+device: 0.842
+mistranslation: 0.797
+performance: 0.775
+architecture: 0.766
+user-level: 0.753
+semantic: 0.731
+register: 0.700
+risc-v: 0.670
+VMM: 0.655
+peripherals: 0.647
+kernel: 0.622
+network: 0.616
+files: 0.597
+TCG: 0.589
+PID: 0.568
+permissions: 0.564
+boot: 0.560
+socket: 0.558
+hypervisor: 0.448
+i386: 0.439
+arm: 0.414
+assembly: 0.372
+virtual: 0.364
+x86: 0.224
+KVM: 0.089
+
+ppc64le linux user emulation w/ 64KiB pages seems broken since v5.0.0
+Description of problem:
+[Our (snmalloc's)](https://github.com/microsoft/snmalloc) CI includes running a PowerPC64 little-endian Linux build inside qemu, running with 64KiB pages as, at least, Debian runs them by default.  As reported [over there](https://github.com/microsoft/snmalloc/issues/576), this broke when GitHub's CI runners moved from Ubuntu Focal (20.04) to Jammy (22.04), bringing qemu from v4.2 to v6.2.
+
+The failing test case appears to die of an erroneous `SIGSEGV` `SEGV_MAPERR`:
+```
+--- SIGSEGV {si_signo=SIGSEGV, si_code=1, si_addr=0x0000004001be5000} ---
+```
+despite that address nominally being mapped by the last memory syscall to touch that area
+```
+openat(AT_FDCWD,"/usr/powerpc64le-linux-gnu/lib/libstdc++.so.6",O_RDONLY|O_CLOEXEC) = 4
+[...]
+mmap(0x0000004001bd0000,131072,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_DENYWRITE|MAP_FIXED,4,0x2f0000) = 0x4001bd0000
+```
+
+Bisection reveals that the breakage first occurred with 4dcf078f094d436866ef793aa25c96fba85ac8d0, though I suspect this is merely the commit that exposes some underlying bug rather than being the actual root cause.
+Steps to reproduce:
+Run a ppc64el Linux executable under `qemu-user` with `-p 65536`.
+Additional information:
+Please advise what more would be useful.