Re: [PATCH 0/2] hw/acpi: bump MADT to revision 5

[Michael S. Tsirkin]

On Thu, Mar 30, 2023 at 07:32:59PM +0530, Ani Sinha wrote:
> 
> 
> On Thu, 30 Mar 2023, Michael S. Tsirkin wrote:
> 
> > On Thu, Mar 30, 2023 at 01:06:36PM +0530, Ani Sinha wrote:
> > >
> > >
> > > On Wed, 29 Mar 2023, Michael S. Tsirkin wrote:
> > >
> > > > On Wed, Mar 29, 2023 at 08:14:37AM -0500, Eric DeVolder wrote:
> > > > >
> > > > >
> > > > > On 3/29/23 00:19, Michael S. Tsirkin wrote:
> > > > > > Hmm I don't think we can reasonably make such a change for 8.0.
> > > > > > Seems too risky.
> > > > > > Also, I feel we want to have an internal (with "x-" prefix") flag to
> > > > > > revert to old behaviour, in case of breakage on some guests.  and 
> > > > > > maybe
> > > > > > we want to keep old revision for old machine types.
> > > > > Ok, what option name, for keeping old behavior, would you like?
> > > >
> > > > Don't much care. x-madt-rev?
> > > >
> > > > > >
> > > > > >
> > > > > > On Tue, Mar 28, 2023 at 11:59:24AM -0400, Eric DeVolder wrote:
> > > > > > > The following Linux kernel change broke CPU hotplug for MADT 
> > > > > > > revision
> > > > > > > less than 5.
> > > > > > >
> > > > > > >   commit e2869bd7af60 ("x86/acpi/boot: Do not register processors 
> > > > > > > that cannot be onlined for x2APIC")
> > > > > >
> > > > > > Presumably it's being fixed? Link to discussion? Patch fixing that 
> > > > > > in
> > > > > > Linux?
> > > > >
> > > > > https://lore.kernel.org/linux-acpi/20230327191026.3454-1-eric.devolder@oracle.com/T/#t
> > > >
> > > > Great! Maybe stick a Link: tag in the commit log.
> > >
> > > If the original bug is in the kernel and kernel upstream has accepted both
> > > your fix and Mario's patch on the acpi revision mess, I see no urgency to
> > > fix this in QEMU.
> > >
> > > Maybe we can address this in the 8.1 development window.
> >
> > Why "maybe"? Eric is working on a patch I don't see why we won't
> > address it.
> >
> 
> I am not opposed to addressing it. I just think it might be too risky for
> 8.0 given that we are already past the hard feature freeze date.

This does not look to me like a justified change for 8.0.
We have rev = 1 for years.

-- 
MST