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Re: [PATCH v2] hw/i386: place setup_data at fixed place in memory
From: |
Jason A. Donenfeld |
Subject: |
Re: [PATCH v2] hw/i386: place setup_data at fixed place in memory |
Date: |
Thu, 18 Aug 2022 17:38:37 +0200 |
Hey Gerd,
On Tue, Aug 16, 2022 at 10:55:11AM +0200, Gerd Hoffmann wrote:
> Hi,
>
> > > We can make setup_data chaining work with OVMF, but the whole chain
> > > should be located in a GPA range that OVMF dictates.
> >
> > It sounds like what you describe is pretty OVMF-specific though,
> > right? Do we want to tie things together so tightly like that?
> >
> > Given we only need 48 bytes or so, isn't there a more subtle place we
> > could just throw this in ram that doesn't need such complex
> > coordination?
>
> Joining the party late (and still catching up the thread). Given we
> don't need that anyway with EFI, only with legacy BIOS: Can't that just
> be a protocol between qemu and pc-bios/optionrom/*boot*.S on how to pass
> those 48 bytes random seed?
Actually, I want this to work with EFI, very much so.
If our objective was to just not break EFI, the solution would be
simple: in the kernel we can have EFISTUB ignore the setup_data field
from the image, and then bump the boot header protocol number. If QEMU
sees the boot protocol number is below this one, then it won't set
setup_data. Done, fixed.
Except I think there's value in passing seeds even through with EFI.
Your option ROM idea is interesting; somebody mentioned that elsewhere
too I think. I'm wondering, though: do option ROMs still run when
EFI/OVMF is being used?
Jason
- Re: [PATCH v3] hw/i386: place setup_data at fixed place in memory, (continued)
- Re: [PATCH v3] hw/i386: place setup_data at fixed place in memory, Jason A. Donenfeld, 2022/08/05
- Re: [PATCH v3] hw/i386: place setup_data at fixed place in memory, Laszlo Ersek, 2022/08/05
- Re: [PATCH v3] hw/i386: place setup_data at fixed place in memory, Jason A. Donenfeld, 2022/08/09
- Re: [PATCH v3] hw/i386: place setup_data at fixed place in memory, Michael S. Tsirkin, 2022/08/09
- Re: [PATCH v3] hw/i386: place setup_data at fixed place in memory, Daniel P . Berrangé, 2022/08/09
- Re: [PATCH v2] hw/i386: place setup_data at fixed place in memory, Laszlo Ersek, 2022/08/05
- Re: [PATCH v2] hw/i386: place setup_data at fixed place in memory, Gerd Hoffmann, 2022/08/16
- Re: [PATCH v2] hw/i386: place setup_data at fixed place in memory,
Jason A. Donenfeld <=
- Re: [PATCH v2] hw/i386: place setup_data at fixed place in memory, Gerd Hoffmann, 2022/08/19
- Re: [PATCH v2] hw/i386: place setup_data at fixed place in memory, Ard Biesheuvel, 2022/08/19
- Re: [PATCH v2] hw/i386: place setup_data at fixed place in memory, Daniel P . Berrangé, 2022/08/04
- Re: [PATCH v2] hw/i386: place setup_data at fixed place in memory, Jason A. Donenfeld, 2022/08/04