Re: [Qemu-ppc] [PATCH] Workaround to bypass default qemu boot devices passed to SLOF

[Nikunj A Dadhania]

On Fri, 5 Oct 2012 12:24:47 +0200, Alexander Graf <address@hidden> wrote:
> 
> 
> On 05.10.2012, at 10:29, Avik Sil <address@hidden> wrote:
> 
> > Hi David,
> > 
> > Please find below the patch for working around the default boot device 
> > issue currently being discussed on the list.
> > 
> > Regards,
> > Avik
> > ---
> > 
> > The default qemu boot_devices string passed to firmware is "cad"
> > which creates a confusion whether -boot oprion is specified or
> > not. This patch handles this issue by setting a global flag when
> > no -boot option is specified.
> 
> Hrm. How does x86 distinguish between -boot and bootindex=?

IMHO, that behaviour is not changed with this patch. Not sure how
seabios is taking care of this.
 
> Also, we could just map -boot c to "nvram given boot device or first
> automatically found disk". Then there's no need to know whether a
> default was given. If you specify -boot you most likely want to force
> cd-rom or network boot anyway and there is no way to tell which disk
> 'c' would reflect.

We do want to use -boot [cad], but not for the nvram saved
boot-device. That is done automatically in SLOF. If there is a property
saved named boot-device, its going to use that for booting.

The point here is when we really want to over-ride the boot-device
setting in nvram(say the boot-device specified got corrupted), we need
help from -boot and corresponding disk provided in the qemu
command-line. 

At present, if there is boot-device specified there is now way to
over-ride it using qemu command line as "cad" is passed by
default. Which is the cause of all the pain. 

Regards,
Nikunj