Messages in this thread | | | Date | Fri, 27 Apr 2007 10:38:05 -0400 | From | Peter Keilty <> | Subject | Re: [PATCH 1/3] ia64: convert to use clocksource code |
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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.
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