lkml.org 
[lkml]   [2007]   [Apr]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 1/3] ia64: convert to use clocksource code
    Daniel Walker wrote:

    >On Thu, 2007-04-26 at 16:26 -0400, Peter Keilty wrote:
    >
    >
    >
    >>+ .mask = (1LL << 40) - 1,
    >>+ .mult = 0, /*to be caluclated*/
    >>+ .shift = 16,
    >>+ .is_continuous = 1,
    >> };
    >>
    >>
    >
    >You should use CLOCKSOURCE_MASK() here ..
    >
    >
    >
    It is correct in patch 3, I believe.

    >
    >
    >>
    >>diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
    >>index daa4940..a20b4d6 100644
    >>--- a/include/linux/clocksource.h
    >>+++ b/include/linux/clocksource.h
    >>@@ -61,6 +61,9 @@ struct clocksource {
    >> u32 shift;
    >> unsigned long flags;
    >> cycle_t (*vread)(void);
    >>+#ifdef CONFIG_IA64
    >>+ void *fsys_mmio_ptr; /* used by fsyscall asm code */
    >>+#endif
    >>
    >>
    >
    >Could you explain in detail why this is needed?
    >
    >
    This ptr is needed to hold the mmio address to read the cycle value.
    The fast ia64 path utilizies a special gate page which can allow user
    code to execute small amount of kernel code, normal calling a function
    not done and so the address is need. The fast syscall path executes on
    user stack, between user/kernel state. And if the the fast path has to
    fallback
    to the slow syscall code the vread will be needed and used.
    Hope this helps.

    >Daniel
    >
    >
    >
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-04-27 16:45    [W:0.028 / U:30.436 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site