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 <p...@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 <p...@philjordan.eu> Message-Id: <1489558827-28971-2-git-send-email-p...@philjordan.eu> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> :040000 040000 40063761c0b86f87e798e03ea48eff9ea0753425 6d2a94150cf1eafb16f0ccf6325281415fef64a6 M hw :040000 040000 fe3f1480a91b76fea238c765f0725e715932d96d 68f9368d8d78fd3267f609b603f97e8a74bdf528 M include :040000 040000 895e961b0a160100aa95b2f557cfe6b87a7d9bff 8ed08cef10fddee7814e38ad62be11371592a75a M tests