Re: [Qemu-devel] [PATCH v5 4/5] hw/i386/pc: use PVH option rom

[Stefano Garzarella <sgarzare@redhat.com>]

Hi Eduardo,

On Mon, Jan 21, 2019 at 03:05:41PM -0200, Eduardo Habkost wrote:
> On Fri, Jan 18, 2019 at 01:01:42PM +0100, Stefano Garzarella wrote:
> > Use pvh.bin option rom when we are booting an uncompressed
> > kernel using the x86/HVM direct boot ABI.
> > 
> > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> > Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> > Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
> > ---
> >  hw/i386/pc.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > index 9ed5063de8..2833b130ba 100644
> > --- a/hw/i386/pc.c
> > +++ b/hw/i386/pc.c
> > @@ -1252,6 +1252,10 @@ static void load_linux(PCMachineState *pcms,
> >                                   initrd_size);
> >              }
> >  
> > +            option_rom[nb_option_roms].bootindex = 0;
> > +            option_rom[nb_option_roms].name = "pvh.bin";
> > +            nb_option_roms++;
> > +
> 
> We still need to address Michael's comment from v2 about
> machine-type compatibility:
> https://www.mail-archive.com/qemu-devel@nongnu.org/msg587489.html

Thanks! (Michael sorry to miss it!)

> 
> A question I've sent is quoted below:
> 
> | On Tue, Jan 15, 2019 at 01:57:22PM -0500, Michael S. Tsirkin wrote:
> | > OK but this is guest visible so needs to be guarded by the
> | > new machine type.
> | 
> | Aren't option ROMs treated like other firmware?  i.e.: guest
> | visible, but copied during live migration and not considered part
> | of guest ABI.

I don't know the exact answer, but reading the wiki, I think Michael is right!
(https://wiki.qemu.org/Features/Migration/Troubleshooting#ROMs)

Maybe it is related for PVH feature in general, because if we try to
migrate to a QEMU version that doesn't support PVH I'm not sure what is
the behaviour.

I'll try to understand better!

Thanks,
Stefano