Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support - Phil Dennis-Jordan

From: Phil Dennis-Jordan <lists@philjordan.eu>
To: Programmingkid <programmingkidx@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Richard Henderson <rth@twiddle.net>,
	ehabkost@redhat.com, Phil Dennis-Jordan <phil@philjordan.eu>,
	"qemu-devel@nongnu.org qemu-devel" <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support
Date: Thu, 20 Jul 2017 21:29:33 +0200	[thread overview]
Message-ID: <CAGCz3vu5x59+mKg8011=DRyZQKbuBV2F20ZpPnG1TOCxsOb+mQ@mail.gmail.com> (raw)
In-Reply-To: <3E24AFDE-D25A-416B-A600-3C2221C3A9F1@gmail.com>

On Thu, Jul 20, 2017 at 6:40 PM, Programmingkid
<programmingkidx@gmail.com> wrote:
> I noticed that Windows 2000 does not boot up in QEMU recently. After bisecting the issue I found the offending commit:

Ouch. I reckon we have 2 options for fixing this:

1. Export two FADTs, one ACPI 1.0, one ACPI 2.0. The latter would need
to be pointed to by an XSDT, which Qemu currently doesn't implement at
all as far as I'm aware. Any ideas on how SeaBIOS or OVMF would handle
this? Any likely other OS regressions?

2. Select FADT version with an option. This one is definitely safe,
but adds yet another option.

Thoughts?

> commit 77af8a2b95b79699de650965d5228772743efe84
> Author: Phil Dennis-Jordan <phil@philjordan.eu>
> Date:   Wed Mar 15 19:20:26 2017 +1300
>
>     hw/i386: Use Rev3 FADT (ACPI 2.0) instead of Rev1 to improve guest OS support.
>
>     This updates the FADT generated for x86/64 machine types from Revision 1 to 3. (Based on ACPI standard 2.0 instead of 1.0) The intention is to expose the reset register information to guest operating systems which require it, specifically OS X/macOS. Revision 1 FADTs do not contain the fields relating to the reset register.
>
>     The new layout and contents remains backwards-compatible with operating systems which only support ACPI 1.0, as the existing fields are not modified by this change, as the 64-bit and 32-bit variants are allowed to co-exist according to the ACPI 2.0 standard. No regressions became apparent in tests with a range of Windows (XP-10) and Linux versions.
>
>     The BIOS tables test suite's FADT checksum test has also been updated to reflect the new FADT layout and content.
>
>     Signed-off-by: Phil Dennis-Jordan <phil@philjordan.eu>
>     Message-Id: <1489558827-28971-2-git-send-email-phil@philjordan.eu>
>     Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>
> :040000 040000 40063761c0b86f87e798e03ea48eff9ea0753425 6d2a94150cf1eafb16f0ccf6325281415fef64a6 M      hw
> :040000 040000 fe3f1480a91b76fea238c765f0725e715932d96d 68f9368d8d78fd3267f609b603f97e8a74bdf528 M      include
> :040000 040000 895e961b0a160100aa95b2f557cfe6b87a7d9bff 8ed08cef10fddee7814e38ad62be11371592a75a M      tests
>
>