Re: [Qemu-devel] [PATCH 0/3] target-i386: Don't trigger "check" warnings by default in KVM mode

[Eduardo Habkost]

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?

-- 
Eduardo