lkml.org 
[lkml]   [2013]   [May]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/3] x86: increase precision of x86_platform.get/set_wallclock()
On 05/13/2013 10:56 AM, David Vrabel wrote:
> From: David Vrabel <david.vrabel@citrix.com>
>
> All the virtualized platforms (KVM, lguest and Xen) have persistent
> wallclocks that have more than one second of precision.
>
> read_persistent_wallclock() and update_persistent_wallclock() allow
> for nanosecond precision but their implementation on x86 with
> x86_platform.get/set_wallclock() only allows for one second precision.
> This means guests may see a wallclock time that is off by up to 1
> second.
>
> Make set_wallclock() and get_wallclock() take a struct timespec
> parameter (which allows for nanosecond precision) so KVM and Xen
> guests may start with a more accurate wallclock time and a Xen dom0
> can maintain a more accurate wallclock for guests.
>
> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
> ---
> arch/x86/include/asm/mc146818rtc.h | 4 ++--
> arch/x86/include/asm/x86_init.h | 6 ++++--
> arch/x86/kernel/kvmclock.c | 9 +++------
> arch/x86/kernel/rtc.c | 17 +++++++----------
> arch/x86/lguest/boot.c | 4 ++--
> arch/x86/platform/efi/efi.c | 10 ++++++----
> arch/x86/xen/time.c | 19 ++++++-------------
> include/linux/efi.h | 4 ++--

Just FYI, David: You missed the vrtc code with this conversion.

I finally got around to pushing my current queue to my public tree and
the kbuild robot noticed the build failure (required INTEL_MID config to
trigger).

The fix I've queued is here:
https://git.linaro.org/gitweb?p=people/jstultz/linux.git;a=commitdiff;h=52d8e9cc6718ae9e6c44b7723028e4717ba91c8b;hp=1dd5234774b33a17743ae62e8b46b5cd0059e1c7

Let me know if you have any objection or comments on this.

thanks
-john



\
 
 \ /
  Last update: 2013-05-29 02:41    [W:0.186 / U:2.132 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site