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Re: [Qemu-devel] [PATCH uq/master] kvm: i8254: Fix conversion of in-kern
From: |
Avi Kivity |
Subject: |
Re: [Qemu-devel] [PATCH uq/master] kvm: i8254: Fix conversion of in-kernel to userspace state |
Date: |
Mon, 11 Jun 2012 13:07:14 +0300 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 |
On 06/06/2012 05:28 PM, Jan Kiszka wrote:
> Due to a offset between the clock used to generate the in-kernel
> count_load_time (CLOCK_MONOTONIC) and the clock used for processing this
> in userspace (vm_clock), reading back the output of PIT channel 2 via
> port 0x61 was broken. One use cases that suffered from it was the CPU
> frequency calibration of SeaBIOS, which also affected IDE/AHCI timeouts.
>
> This fixes it by calibrating the offset between both clocks on
> kvm_pit_get and adjusting the kernel value before saving it in the
> userspace state. As the calibration only works while the vm_clock is
> running, we cache the in-kernel state across stopped phases.
Applied, thanks.
> + clock_offset = LLONG_MAX;
INT64_MAX would me more strictly correct, but in practice it makes no
difference.
--
error compiling committee.c: too many arguments to function