[Qemu-devel] Commit 77af8a2b95b79699de650965d5228772743efe84 breaks Windows 2000 support

[Programmingkid]

I noticed that Windows 2000 does not boot up in QEMU recently. After bisecting 
the issue I found the offending commit:

commit 77af8a2b95b79699de650965d5228772743efe84
Author: Phil Dennis-Jordan <address@hidden>
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 <address@hidden>
    Message-Id: <address@hidden>
    Signed-off-by: Paolo Bonzini <address@hidden>

:040000 040000 40063761c0b86f87e798e03ea48eff9ea0753425 
6d2a94150cf1eafb16f0ccf6325281415fef64a6 M      hw
:040000 040000 fe3f1480a91b76fea238c765f0725e715932d96d 
68f9368d8d78fd3267f609b603f97e8a74bdf528 M      include
:040000 040000 895e961b0a160100aa95b2f557cfe6b87a7d9bff 
8ed08cef10fddee7814e38ad62be11371592a75a M      tests