On 30/10/2015 20:13, Eduardo Habkost wrote: > On Fri, Oct 30, 2015 at 05:00:57PM -0200, Eduardo Habkost wrote: >> The x86 change to make "check" mode be enabled by default made QEMU print a >> warning in the default case if running in an Intel host: >> >> $ qemu-system-x86_64 -machine pc,accel=kvm >> warning: host doesn't support requested feature: CPUID.80000001H:ECX.sse4a >> [bit 6] >> >> Fix this by not enabling sse4a in qemu64 when in KVM mode. >> >> The long term solution will probably involve creating separate "tcg64" and >> "kvm64" CPU models as defaults, so we can finally choose completely >> diffferent >> defaults in the KVM- and TCG-specific models without making the >> kvm_default_props list grow too mcuh. > > Note that we can have a much simpler solution to this: disabling SSE4A > on qemu64 completely, even on TCG. This way we can use PC_COMPAT_2_4 > instead of the kvm_default_props compat hack. > > We can reenable SSE4A for TCG later (more exactly, we could enable > everything from TCG_*_FEATURES) when we implement the kvm64/tcg64 > solution. > > What do you think?
I would prefer that to this series. Another possibility (even more of a hack, but perhaps acceptable) is to disable SSE4A in x86_cpu_load_def if kvm_enabled() and the host vendor is not AMD. This is effectively what was already happening in 2.4 and earlier. Paolo
