I will try to work on this. Regards, Walid
Le mer. 12 avr. 2023 à 15:30, Paolo Bonzini <pbonz...@redhat.com> a écrit : > On Wed, Apr 12, 2023 at 2:17 PM Alex Bennée <alex.ben...@linaro.org> > wrote: > > I don't think there is currently any active effort to add AVX512 > > support. There have been various GSoC projects to improve the x86 SIMD > > emulation but I don't think they got merged. > > No, there isn't. However, the recent implementation of AVX in QEMU 7.2 > is designed to make AVX512 at least doable. > > Adding support for AVX512 would be a very large work (at least 1 > months full time plus time to get it merged), but not impossible. The > tasks could be something like this: > > 1. EVEX prefix decoding for AVX and AVX2 instructions > 2. operand broadcast > 3. VEX encoded mask instruction: kmov, kadd, kxnor, etc > 4. other instructions and permutations with mask operands and permutations > 5. opmask support including merging and zeroing > 6. Disp8*N addressing mode > 7. rounding control and exception suppression > > It's important that, at any given step, the new functionality is > tested comprehensively. > > > > 62 f2 7d 48 18 0d fa 0c 00 00 vbroadcastss 0xcfa(%rip),%zmm1 > > > > > > qemu: uncaught target signal 4 (Illegal instruction) - core dumped > > > > > > I like to add support for broadcast and fmadd avx 512 instructions > such as the following one: > > > > > > 62 e2 7d 48 b8 c9 vfmadd231ps %zmm1,%zmm0,%zmm17 > > Both of these are using a small subset of AVX512 (step 1 above). Both > vbroadcastss and vfmadd231ps are already implemented in QEMU, but not > using ZMM registers. > > Unfortunately the base AVX512 functionality is large, and therefore > the above tasks are all needed to claim support for AVX512. On the > other hand, for historical reasons AVX512BW and AVX512VL extensions > are separate but in practice they are easier to just implement at the > same time as basic AVX512; my expectation is that they would come up > almost for free with the rest of the work. > > Paolo > >
