On Wed, Jun 17, 2009 at 12:58, Marco wrote:
Jared Hulbert wrote:
+#if defined(CONFIG_ARM) || defined(CONFIG_M68K) || defined(CONFIG_H8300) || \
+ ? ? ? defined(CONFIG_BLACKFIN)
+ ? ? ? /*
+ ? ? ? ?* FIXME: so far only these archs have flush_tlb_kernel_page(),
+ ? ? ? ?* for the rest just use flush_tlb_kernel_range(). Not ideal
+ ? ? ? ?* to use _range() because many archs just flush the whole TLB.
+ ? ? ? ?*/
+ ? ? ? if (end <= start + PAGE_SIZE)
+ ? ? ? ? ? ? ? flush_tlb_kernel_page(start);
+ ? ? ? else
+#endif
+ ? ? ? ? ? ? ? flush_tlb_kernel_range(start, end);
+}
Why not just fix flush_tlb_range()?
If an arch has a flush_tlb_kernel_page() that works then it stands to
reason that the flush_tlb_kernel_range() shouldn't work with minimal
effort, no?
flush_tlb_kernel_page() is a new one to me, it doesn't have any mention
in Documentation/cachetlb.txt anyways.
Many of the flush_tlb_kernel_range() implementations do ranged checks
with tunables to determine whether it is more expensive to selectively
flush vs just blowing the entire TLB away.
Likewise, there is no reason why those 4 architectures can not just shove
that if (end <= start + PAGE_SIZE) check in the beginning of their
flush_tlb_kernel_range() and fall back on flush_tlb_kernel_page() for
those cases. Hiding this in generic code is definitely not the way to go.
Ok I'll change that function at arch level and I'll remove the ifdef, I'll call only flush_tlb_kernel_page(), but I'd like to know what is the opinion of the arch maintainers to do that.
considering Blackfin defines flush_tlb_kernel_page() to BUG(), i dont
think we care what happens. we dont have a MMU, so all tlb funcs ->
BUG(). presumably this code shouldnt have been compiled in the first
place for us.
-mike
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