Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime()

From: Leonid Yegoshin
Date: Wed Oct 28 2015 - 15:28:30 EST

On 10/28/2015 12:04 PM, Alex Smith wrote:
On 28 October 2015 at 18:57, Leonid Yegoshin <Leonid.Yegoshin@xxxxxxxxxx> wrote:

As I've explained the VDSO will only use the CP0 counter in the same
situations that the kernel would when it is the active clocksource.
Any issue that makes the counter unreliable affects the kernel as well
and is unrelated to the VDSO, so a fix does not belong in this patch.

What would you do if some SoC with different type of cores will define CPU1 etc CP0_COUNT as a DIFFERENT clocksource from CPU0 (because of frequency etc)? Timekeeping can select CPU0 clocksource but code still uses a local CPU1 CP0_COUNT for gettimeofday().

And this kind of solution is the first in line to have an accurate timing in systems without GIC and with different clock frequencies.

- Leonid

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