[SeaBIOS] Marvell 88SE9230 passthrough in KVM takes long time to boot

[Alex Williamson]

On Wed, 8 Aug 2018 14:11:16 +0200
Gerd Hoffmann <kraxel at redhat.com> wrote:

> On Sun, Jul 29, 2018 at 01:49:10PM +0200, Konrad Eisele wrote:
> > I'm passing through a Marvell 88SE9230 card to a KVM guest under
> > Ubuntu 18.04. The card is a Sata controller with 4 ports.
> > The option rom of the Marvell 88SE9230 card shows on a normal boot a
> > bios screen. When pressing CTRL-m quick enough, you  can interrupt the
> > bootprocess and enter a menue wherer you can define raid
> > arrays.
> > 
> > When booting seabios inside KVM the bootprocess is very slow.
> > There is a 1 min holdtime where the cpu is about 30%. The screen is
> > black with only the seabios version string shown. I suspect that
> > the passed-through Marvell 88SE9230 cards option roms causes this
> > behaviour.
> > Maybe the scanning for option rom cause the slow bootprocess?
> > 
> > In the seabios boot case no bios menue is shown, after
> > around 1 min the boot continues.
> > 
> > Is it possible to disable the options rom processing? Is there some
> > documentation about this (How can I configure it for Ubuntu) ?  
> 
> Set the romfile option to the empty string (for vfio-pci, on the qemu
> command line) should do that (qemu will not expose the rom to the guest
> then).

Typically rombar=0 on the QEMU command line is how to disable the option
ROM for an assigned device, or

<rom bar='off'/>

in libvirt.  Thanks,

Alex