Re: allocating non-cacheable regions

[Steve Rossi <srossi@ccrl.mot.com>]

I'm back on this ... with another question. Following the examples in
commproc.c and enet.c - does setting the _PAGE_NO_CACHE flag
for a page table entry also invalidate any cached data for that page?
I am observing a write-though behavior when I write to addresses in
the _PAGE_NO_CACHE page but when I read from addresses marked
as _PAGE_NO_CACHE it appears to be retrieving data from the cache
not from memory. Is this expected behavior? How can I make it so that
reads as well as writes to a particular page bypass the cache?

Thanks,
Steve

Dan Malek wrote:

> Steve Rossi wrote:
> >
> > How do I allocate a region of memory that is flagged as being
> > non-cacheable?
>
> For an example, look at the commproc.c or enet.c driver in the
> arch/ppc/8xx_io directory.  When pages are allocated, the PTEs are
> tracked down and marked non-cache.
>

--
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Steven K. Rossi                     srossi@ccrl.mot.com
Staff Engineer
Multimedia Communications Research Laboratory
Motorola Labs
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