Re: [Qemu-devel] FW_CFG_NB_CPUS vs fwcfg file 'etc/boot-cpus'

[Kevin O'Connor]

On Fri, Nov 11, 2016 at 03:36:19PM +0100, Igor Mammedov wrote:
> On Fri, 11 Nov 2016 15:02:36 +0100
> Laszlo Ersek <address@hidden> wrote:
> 
> > adding Jeff Fan and Jordan Justen
> > 
> > On 11/11/16 13:57, Igor Mammedov wrote:
> > > While looking at OVMF and how it handles CPUs (ACPI/AP wakeup),
> > > I've noticed that it uses legacy FW_CFG_NB_CPUS(0x05) to get
> > > the number of present at start CPUs.  
> > 
> > Where exactly do you see this?
> That's the only place in OVMF, but according to google there are
> other firmwares that use FW_CFG_NB_CPUS so we are not free to remove
> it and break guests.
> 
> So I'd just drop not yet released 'etc/boot-cpus',
> of cause SeaBIOS should be fixed and its blob in QEMU updated.

I have no preference between FW_CFG_NB_CPUS and 'etc/boot-cpus'.  Note
that SeaBIOS v1.10 was released with the code using 'etc/boot-cpus'
though.  If it's to go away, we'll need a SeaBIOS stable branch
release with the change.

-Kevin