| commit | 486eacda3a8fe32d7359bff36d0caa1b8fffd12b | |
| author | Marcelo Tosatti <marcelo@kvack.org> | |
| Fri, 11 Jan 2008 21:26:55 +0000 (11 19:26 -0200) | ||
| committer | Avi Kivity <avi@qumranet.com> | |
| Sun, 13 Jan 2008 10:24:47 +0000 (13 12:24 +0200) | ||
| tree | fd67c2ab38d857a1f9f490500e97396716ac302d | treesnapshot (tar.gz zip) |
| parent | ec61b86f8235646aedf1029669bf522755eebe08 | commitdiff |
Report revision 3 of the ACPI/SMBus PIIX4 controller
The PIIX4 ACPI controller prior to revision 0x3 contains a bug where
reading of the timer port is unreliable, so the kernel reads it three
times for consistency check.
QEMU does not suffer from that problem :)
The datasheet for PIIX4, PIIX4E, and PIIX4M is the same. I failed to
find any indication that the revision increase could affect anything
other than the PMTimer port read.
This reduces idle guest CPU consumption from 14% to 8% on 4-way KVM
guest.
Signed-off-by: Avi Kivity <avi@qumranet.com>
The PIIX4 ACPI controller prior to revision 0x3 contains a bug where
reading of the timer port is unreliable, so the kernel reads it three
times for consistency check.
QEMU does not suffer from that problem :)
The datasheet for PIIX4, PIIX4E, and PIIX4M is the same. I failed to
find any indication that the revision increase could affect anything
other than the PMTimer port read.
This reduces idle guest CPU consumption from 14% to 8% on 4-way KVM
guest.
Signed-off-by: Avi Kivity <avi@qumranet.com>
| hw/acpi.c | diffblobblamehistory |