Messages in this thread | | | Date | Thu, 23 Feb 2023 08:01:08 +0100 | Subject | Re: [PATCH] KVM: x86: disable on 32-bit unless CONFIG_BROKEN | From | Thomas Huth <> |
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On 22/02/2023 23.27, Sean Christopherson wrote: > On Fri, Feb 17, 2023, Thomas Huth wrote: >> 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. > > Ya, I would happily drop support for 32-bit kernels today, the only sticking point > is the lack of 32-bit shadow paging test coverage, which unfortunately is a rather > large point. :-(
From your point of view, would it be OK if QEMU dropped qemu-system-i386? I.e. would it be fine to use older versions of QEMU only for that test coverage (or do you even use a different userspace for testing that)?
Thomas
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