* Richard Henderson: > On 5/24/22 02:27, Florian Weimer wrote: >> * Richard Henderson: >> >>> On 5/13/22 03:00, Florian Weimer wrote: >>>> What's QEMU's approach to emulating CPU instructions that atomatically >>>> operate on values larger than what is supported by the host CPU? >>>> I assume that for full system emulation, this is not a problem, but >>>> qemu-user will not achieve atomic behavior on shared memory mappings. >>>> How much of a problem is this in practice? >>> >>> Well, it doesn't work, no. In practice, x86_64 supports 128-bit >>> atomic operations, and guest requires more than that. No one really >>> cares anymore about 32-bit hosts with smaller atomic operations. >> Which part doesn't work? Full-system emulation? > > No, user-only. > >> Do guests really require wider-than-128 atomics? That's quite >> surprising? > > Typo there -- "and no guest requires...".
Okay, thanks. So the overall situation is okay even if we end up with x86 guests that require CPU support for 128-bit loads. Florian
