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Re: [Qemu-devel] [SeaBIOS] Commit 77af8a2b95b79699de650965d5228772743efe
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [SeaBIOS] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support |
Date: |
Wed, 26 Jul 2017 16:21:23 -0400 (EDT) |
> > (4) would be acceptable I guess. However I think it's a bit worse
> > because fw-cfg files are a somewhat scarce resource. The "legacy"
> > aspect is something that SeaBIOS is in the best position to address,
> > because it knows what OSes are running on it; QEMU instead only takes
> > care of describing the hardware.
>
> SeaBIOS is used with both modern and legacy OSes, and it doesn't have
> any knowledge about what kind of OS will be used. If anything, I'd
> argue that QEMU has more knowledge about the guest OS than SeaBIOS
> does (due to command-line options like machine version).
No, the machine type is independent from the guest OS. The aim is to
let "qemu-system-x86_64 -m MEMORYSZ image.qcow2" work just fine with
every guest OS.
> As I see it, fundamentally the proposal here is to deploy different
> ACPI tables when using SeaBIOS then when using OVMF. I think that's
> fine, but I think we should directly address that issue then.
The different ACPI tables are essentially a bug in OVMF. They can be
fixed to be the same.
> Specifically, I have the following concerns with the original approach:
>
> A - It would require deploying SeaBIOS and QEMU in lock-step. To get
> this in for QEMU v2.10 would require making QEMU changes during
> the soft freeze and would require a SeaBIOS "stable" release that
> introduces ACPI table manipulation.
Yes.
> B - I don't have full confidence the proposed ACPI changes wont expose
> a quirk in some obscure OS from the last 25 years. If it does
> expose a quirk, any work-around would likely require deploying a
> new SeaBIOS and QEMU in lock-step.
Well, the solution is proposed by ACPI itself, and the worst that can
happen is that some OS prefers the RSDT to the XSDT (which we already
test on Windows 2000).
> C - We'd be introducing "shared ownership" of the acpi tables. Some
> of the tables would be produced by QEMU and some of them by
> SeaBIOS. Explaining when and why to future developers would be a
> challenge.
The advantage is that the same shared ownership is already present in
OVMF. The RSDP/RSDT/XSDT are entirely created by the firmware in OVMF.
(The rev1 FADT isn't but that's just missing code; the table manager
in general would be ready for that). In any case this doesn't seem
like something that cannot be solved by code comments.
Paolo
- Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, (continued)
- Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Laszlo Ersek, 2017/07/25
- Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Paolo Bonzini, 2017/07/25
- Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Paolo Bonzini, 2017/07/25
- Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Phil Dennis-Jordan, 2017/07/25
- Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Paolo Bonzini, 2017/07/26
- Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Laszlo Ersek, 2017/07/26
- Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Paolo Bonzini, 2017/07/26
- Re: [Qemu-devel] [SeaBIOS] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Kevin O'Connor, 2017/07/25
- Re: [Qemu-devel] [SeaBIOS] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Paolo Bonzini, 2017/07/26
- Re: [Qemu-devel] [SeaBIOS] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Kevin O'Connor, 2017/07/26
- Re: [Qemu-devel] [SeaBIOS] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support,
Paolo Bonzini <=
- Re: [Qemu-devel] [SeaBIOS] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Gerd Hoffmann, 2017/07/27
- Re: [Qemu-devel] [SeaBIOS] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Paolo Bonzini, 2017/07/27
- Re: [Qemu-devel] [SeaBIOS] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Kevin O'Connor, 2017/07/27
- Re: [Qemu-devel] [SeaBIOS] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Laszlo Ersek, 2017/07/27
- Re: [Qemu-devel] [SeaBIOS] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Gerd Hoffmann, 2017/07/28
- Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Igor Mammedov, 2017/07/26
- Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Paolo Bonzini, 2017/07/26
- Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Igor Mammedov, 2017/07/26
- Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Paolo Bonzini, 2017/07/26
- Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support, Igor Mammedov, 2017/07/26