Re: [Libguestfs] [PATCH] always 'max' for the appliance CPU model on all targes except ppc
On Thu, 26 May 2022 at 09:17, Daniel P. Berrangé <berrange(a)redhat.com> wrote:
We've never said that 'max' is the same for TCG and KVM,
nor do
apps using it require/expect that to be the case.
It is simply intended to expose the maximum featureset available to
any given accelerator backend. On KVM "maximum featureset" is the
same as "host" as you can't expose more than what the hardware has,
while on TCG "maximum featureset" is the most that emulation supports.
The intent is/was that it serves as good CPU choice for apps which
maximises features available, without them needing to think.
Yes, and I don't think that Arm is any different here from
the various other target architectures where you're using 'max'
already. The only difference is that on older QEMU versions
target/arm didn't implement 'max' for both KVM and TCG, which is
why you previously had to effectively simulate a slightly suboptimal
version of it with
(kvm ? "host" : "cortex-a57").
thanks
-- PMM