[lkml]   [2007]   [Sep]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    Patch in this message
    SubjectRe: 2.6.23-rc3-mm1 - vdso and gettimeofday issues with glibc

    > Updating on this issue: Both myself and another person have reported on
    > the RedHat bugzilla that it's a clocksource issue - if you are using the
    > hpet clocksource, the time warps, but booting with clocksource=acpi_pm works.
    > This ring any bells?

    Does this patch fix it?

    Add missing mask operation to vdso

    vdso vgetns() didn't mask the time source offset calculation, which could
    lead to time problems with 32bit HPET. Add the masking.

    Thanks to Chuck Ebbert for tracking down.

    Signed-off-by: Andi Kleen <>

    Index: linux/arch/x86_64/vdso/vclock_gettime.c
    --- linux.orig/arch/x86_64/vdso/vclock_gettime.c
    +++ linux/arch/x86_64/vdso/vclock_gettime.c
    @@ -34,10 +34,11 @@ static long vdso_fallback_gettime(long c

    static inline long vgetns(void)
    + long v;
    cycles_t (*vread)(void);
    vread = gtod->clock.vread;
    - return ((vread() - gtod->clock.cycle_last) * gtod->clock.mult) >>
    - gtod->clock.shift;
    + v = (vread() - gtod->clock.cycle_last) & gtod->clock.mask;
    + return (v * gtod->clock.mult) >> gtod->clock.shift;

    static noinline int do_realtime(struct timespec *ts)
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at
     \ /
      Last update: 2007-09-09 09:29    [W:0.020 / U:70.640 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site