On Tue, Jan 17, 2023 at 05:43:53PM +0100, Ard Biesheuvel wrote: > On Tue, 17 Jan 2023 at 13:37, Gerd Hoffmann <kra...@redhat.com> wrote: > > > > Hi, > > > > > >> In particular the firmware makes no further decisions based on > > > >> whether QEMU advertized some of these features. > > > > > > > > I was thinking the other way around: When cpu hotplug is disabled in > > > > qemu it should be safe to skip the whole cpu hotplug checking dance. > > > > See test patch below. > > > > > > > > That would give us a config switch (turn off cpu hotplug support) > > > > which would allow edk2 run on qemu versions with broken cpu hotplug. > > > > > > > > Does the idea look sane or do I miss something? > > > > > This would be wrong. > > > > > > [ detailed description snipped here (but stored for later reference, > > > thanks for all the details) ] > > > > So, the tl;dr version: cpu hotplug is older than smi feature > > negotiation, so smi hotplug feature bit being off doesn't imply > > qemu wouldn't hotplug cpus. > > > > So, no easy way out. Luckily this affects tcg only. > > > > For edk2 ci doing (tcg) efi shell test boots switching to Oliver's > > latest containers with fixed qemu included should handle things > > (latest series just posted). So once this is in we should be able to > > merge this patch without breaking CI. > > My head is spinning. > > What about running QEMU with only a single CPU, and without any of > these features? Is there really no way we can make that work without > turning OVMF into the timebomb that Laszlo describes?
I can't see any way :( ovmf seeing only a single cpu does not imply cpu hotplug can't happen, it could be "qemu -smp cpus=1,maxcpus=4". Figuring the maxcpus number depends on the broken cpu hotplug registers. > It's just very annoying that on a non-KVM host and a given QEMU > binary, you might simply be out of luck entirely, and there is no way > you can run OVMF with the fix applied. I would like to avoid that if > possible. Indeed. take care, Gerd -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#98768): https://edk2.groups.io/g/devel/message/98768 Mute This Topic: https://groups.io/mt/96218818/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
