RE: Cache coherency and snooping

[Imran Badr]

Thanks Ralf and Alan,

What if I allocate memory at boot-time using alloc_bootmem*(..)?

Imran.

-----Original Message-----
From: Ralf Baechle [mailto:[e-mail]]
Sent: Tuesday, August 13, 2002 5:08 PM
To: Imran Badr
Cc: [e-mail]
Subject: Re: Cache coherency and snooping

On Tue, Aug 13, 2002 at 04:22:31PM -0700, Imran Badr wrote:

> How can I define a certain region of memory so that it is never cached? I
> want to use non-cached region of memory to communicate to my PCI device to
> avoid system overhead in cache snooping.

On every sane platform the hardware performs better at keeping the
coherency than software ever could.  Don't even think about it unless
you for some reason absolutely must disable caching.  Aside and as Alan
already mentioned the allocation of uncached memory isn't supported.

  Ralf