From: Anthony Liguori <anthony@codemonkey.ws>
To: Jordan Justen <jljusten@gmail.com>
Cc: qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] OVMF, SeaBIOS & non-CSM based legacy boot
Date: Mon, 21 Mar 2011 13:27:41 -0500 [thread overview]
Message-ID: <4D87989D.70005@codemonkey.ws> (raw)
In-Reply-To: <AANLkTi=c8DwrC9dxPmVA4vNg2-2NJn844m=eOMQBNJHd@mail.gmail.com>
On 03/21/2011 01:14 PM, Jordan Justen wrote:
> This weekend I spent some time working on loading SeaBIOS from OVMF to
> start a legacy boot. I was able to get x86& x86-64 Linux to legacy
> boot using this method.
>
> Unfortunately, (I think) it is not nearly as nice a having a true CSM.
> Basically, you have to decide at some point in the OVMF boot that you
> want to legacy boot, and once you start SeaBIOS running, OVMF/UEFI
Interesting. How much time does OVMF add to the total boot time when
taking this approach?
> will never be in the picture again (until system reset).
>
> Contrast this to using a CSM where you can:
> * Load a legacy option ROM (vbios, or disk rom),
> and use it during a UEFI boot
Is there gPXE for UEFI yet?
Other than that, this probably matters most of with device passthrough.
I think this is a limitation we could live with in the not-to-short term
though.
> * Fail a legacy boot, and potentially return back to UEFI if it fails.
> (Not in all cases, if the failed boot alters the system state significantly)
I think the most typical use-case here is -boot cd or -boot dc. From
what I can tell, EFI support El Torito so it wouldn't be necessary to
involve BIOS to handle booting from CDROMs. Is that correct?
> * Specify via UEFI the boot process which disk to legacy boot in the CSM
I'm sure this is workable.
> So, would this be valuable (in the short term) to help move forward
> QEMU's usage of OVMF and add UEFI support? Or would QEMU require true
> CSM support?
I think this certainly helps make the discussion more concrete. I don't
see any show stoppers here.
Regards,
Anthony Liguori
> Thanks,
>
> -Jordan
>
next prev parent reply other threads:[~2011-03-21 18:27 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-21 18:14 [Qemu-devel] OVMF, SeaBIOS & non-CSM based legacy boot Jordan Justen
2011-03-21 18:27 ` Anthony Liguori [this message]
2011-03-21 21:06 ` Stefan Hajnoczi
2011-03-21 21:17 ` Michael Brown
2011-03-21 21:31 ` Jordan Justen
2011-03-21 21:40 ` Stefan Hajnoczi
2011-03-21 23:14 ` Michael Brown
2011-03-21 21:23 ` Jordan Justen
2011-03-22 8:00 ` Gleb Natapov
2011-03-22 19:28 ` Jordan Justen
2011-03-22 20:07 ` Gleb Natapov
2011-03-22 21:53 ` Jordan Justen
2011-03-23 12:36 ` Gleb Natapov
2011-03-23 22:32 ` Jordan Justen
2011-03-24 11:53 ` Gleb Natapov
2011-03-24 16:46 ` Jordan Justen
2011-03-24 18:36 ` Gleb Natapov
2011-03-24 12:27 ` Michal Suchanek
2011-03-24 13:44 ` Gleb Natapov
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