Messages in this thread | | | Date | Wed, 14 Aug 2002 10:16:54 +0200 | From | Ralf Baechle <> | Subject | Re: Cache coherency and snooping |
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On Tue, Aug 13, 2002 at 06:00:43PM -0700, Imran Badr wrote:
> Please advise if following sequence of operations are going to help: > > alloc memory > reserve the page > flush every cache
That's an extremly expensive operation on some platforms and there's no portable kernel API to do it.
Note that the flush_cache_*() functions are not suitable for I/O as you want to do it. Many platforms such as i386 implement these functions as empty functions.
> call ioremap_nocache
You said you intend to remap memory, that is RAM. The ioremap*() functions will refuse to remap RAM; they're only suitable for other types of memory such as PCI boards. If the latter was your intension then ioremap_nocache() will work as intended.
Again, unless your hardware is fucked beyond recognition it'll do a better job at keeping cache coherence than software.
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