Re: [PATCH 1/3] x86: increase precision of x86_platform.get/set_wallclock()
From: John Stultz
Date: Tue May 28 2013 - 20:18:11 EST
On 05/13/2013 10:56 AM, David Vrabel wrote:
From: David Vrabel <david.vrabel@xxxxxxxxxx>
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@xxxxxxxxxx>
---
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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/