[Expired for QEMU because there has been no activity for 60 days.] ** Changed in: qemu Status: Incomplete => Expired
-- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1916269 Title: TCG: QEMU incorrectly raises exception on SSE4.2 CRC32 instruction Status in QEMU: Expired Bug description: If I run FreeBSD on QEMU 5.2 with TCG acceleration -cpu Nehalem, I get a FPU exception when executing crc32 (https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=253617). This is not a problem with the default CPU (or KVM) since that does not support SSE 4.2. Attaching GDB shows this is triggered in target/i386/tcg/translate.c:3067 /* simple MMX/SSE operation */ if (s->flags & HF_TS_MASK) { gen_exception(s, EXCP07_PREX, pc_start - s->cs_base); return; } However, according to https://software.intel.com/sites/default/files/m/8/b/8/D9156103.pdf, page 61 the CRC32 instruction works no matter what the value of the TS bit. The code sequence in question is: 0xffffffff8105a4de <+126>: f2 48 0f 38 f1 de crc32q %rsi,%rbx 0xffffffff8105a4e4 <+132>: f2 48 0f 38 f1 ca crc32q %rdx,%rcx. This should work even with the FPU disabled. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1916269/+subscriptions