Re: [PATCH] KVM: x86: disable on 32-bit unless CONFIG_BROKEN
From: Thomas Huth
Date: Fri Feb 17 2023 - 14:37:33 EST
On 29/09/2022 15.52, Maxim Levitsky wrote:
On Thu, 2022-09-29 at 15:26 +0200, Paolo Bonzini wrote:
On 9/28/22 19:55, Sean Christopherson wrote:
As far as my opinion goes I do volunteer to test this code more often,
and I do not want to see the 32 bit KVM support be removed*yet*.
Yeah, I 100% agree that it shouldn't be removed until we have equivalent test
coverage. But I do think it should an "off-by-default" sort of thing. Maybe
BROKEN is the wrong dependency though? E.g. would EXPERT be a better option?
Yeah, maybe EXPERT is better but I'm not sure of the equivalent test
coverage. 32-bit VMX/SVM kvm-unit-tests are surely a good idea, but
what's wrong with booting an older guest?
From my point of view, using the same kernel source for host and the guest
is easier because you know that both kernels behave the same.
About EXPERT, IMHO these days most distros already dropped 32 bit suport thus anyway
one needs to compile a recent 32 bit kernel manually - thus IMHO whoever
these days compiles a 32 bit kernel, knows what they are doing.
I personally would wait few more releases when there is a pressing reason to remove
this support.
FWIW, from the QEMU perspective, it would be very helpful to remove 32-bit
KVM support from the kernel. The QEMU project currently struggles badly with
keeping everything tested in the CI in a reasonable amount of time. The
32-bit KVM kernel support is the only reason to keep the qemu-system-i386
binary around - everything else can be covered with the qemu-system-x86_64
binary that is a superset of the -i386 variant (except for the KVM part as
far as I know).
Sure, we could also drop qemu-system-i386 from the CI without dropping the
32-bit KVM code in the kernel, but I guess things will rather bitrot there
even faster in that case, so I'd appreciate if the kernel could drop the
32-bit in the near future, too.
Thomas