Cachable / Non-cachable memory

Cachable / Non-cachable memory

[raphael.bossek]

Hi,

how does Linux specify memory regions as cachable and non-
cachable? It is sometimes required to mark mapped memory
regions from devices as non-cachable by the MMU so the PowerPC
does not tune the write/read accesses.

Is there any function or sample driver code in the mpc8xx-linux
2.2.13 code ?

cu Raphael Bossek - http://www.solutions4linux.de/powerpc.html

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Re: Cachable / Non-cachable memory

[szg98]

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In arch/ppc/mm/init.c,
the mpc8xx-linux code use map_page(v,p,flags),
to set one memory page to some properities,like _NO_CACHE_PAGE,etc.





raphael.bossek@solutions4linux.de ÔÚ 2000-01-28 17:31:23

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Hi,

how does Linux specify memory regions as cachable and non-
cachable? It is sometimes required to mark mapped memory
regions from devices as non-cachable by the MMU so the PowerPC
does not tune the write/read accesses.

Is there any function or sample driver code in the mpc8xx-linux
2.2.13 code ?

cu Raphael Bossek - http://www.solutions4linux.de/powerpc.html


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Re: Cachable / Non-cachable memory

[Dan Malek]

raphael.bossek@solutions4linux.de wrote:


> how does Linux specify memory regions as cachable and non-
> cachable?


Any memory mapping request outside of the range of real
memory is mapped uncached/guarded.  Look at drivers/char/mem.c

Driver requests to ioremap() are mapped uncached/guarded.


	-- Dan

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