>>> On 15.01.15 at 15:14, <jbeul...@suse.com> wrote: > But I think I made a wrong assumption above regarding the > guest size: test-amd64-i386-xl-win7-amd64 produces a 64-bit > guest with a 32-bit tool stack, so the crucial part of all the > tests failing is not the guest's bitness, but tool stack's. So I'll > next look into which of the three feature flags might be off > when inspected from a 32-bit Dom0, as I now suspect that the > guest simply doesn't get its CPUID bits correctly set up by a > 32-bit Dom0 (i.e. the patch might just have uncovered a latent > bug).
And there you go: The hypervisor deliberately clears the syscall feature flag for 32-bit PV guests on non-AMD CPUs, and hardware appears to do so too when CPUID gets executed from a non-64-bit CS (i.e. no matter whether you execute raw or "Xen-ified" CPUID there, you won't see that flag set). Yet 64-bit guests won't be bothered to check whether the flag is enabled, as x86-64 requires the feature to be there. But I think even if this could be taken care of in the tool stack, it's better to have hvm_cpuid() mimic that behavior, i.e. force FEATURE_SYSCALL on when hvm_guest_x86_mode() == 8. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
