On Wed, 2022-09-28 at 16:12 +0000, Sean Christopherson wrote: > On Wed, Sep 28, 2022, Paolo Bonzini wrote: > > On 9/28/22 09:10, Maxim Levitsky wrote: > > > I also think that outside KVM developers nobody should be using KVM on 32 bit host. > > > > > > However for_developement_ I think that 32 bit KVM support is very useful, as it > > > allows to smoke test the support for 32 bit nested hypervisors, which I do once in a while, > > > and can even probably be useful to some users (e.g running some legacy stuff in a VM, > > > which includes a hypervisor, especially to run really legacy OSes / custom bare metal software, > > > using an old hypervisor) - or in other words, 32 bit nested KVM is mostly useless, but > > > other 32 bit nested hypervisors can be useful. > > > > > > Yes, I can always use an older 32 bit kernel in a guest with KVM support, but as long > > > as current kernel works, it is useful to use the same kernel on host and guest. > > > > Yeah, I would use older 32 bit kernels just like I use RHEL4 to test PIT > > reinjection. :) But really the ultimate solution to this would be to > > improve kvm-unit-tests so that we can compile vmx.c and svm.c for 32-bit. > > Agreed. I too use 32-bit KVM to validate KVM's handling of 32-bit L1 hypervisors, > but the maintenance cost is painfully high. > But is it actually? I test it routinely and it it does work quite well IMHO. I don't remember that there were that much breakage lately in this area. 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*. Best regards, Maxim Levitsky
