Hi Adam,
If you have a look in include/asm-ppc/pgtable.h for the following section:
#ifdef CONFIG_44x
#define _PAGE_BASE (_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_GUARDED)
#else
#define _PAGE_BASE (_PAGE_PRESENT | _PAGE_ACCESSED)
#endif
Try adding _PAGE_COHERENT to the appropriate line above and see if that
fixes your issue - this causes the 'M' bit to be set on the page which
sure enforce cache coherency. If it doesn't, you'll need to check the
'M' bit isn't being masked out in head_44x.S (it was originally masked
out on arch/powerpc, but was fixed in later kernels when the cache
coherency issues with non-SMP systems were resolved).
The patch I had fixed two problems on 2.6.26 for 'powerpc':
1) It stopped the 'M' bit being masked out (head_32.S)
2) It set the cache coherency ('M' bit) flag on each page table entry
(pgtable-ppc32.h)
Hope this helps!
Cheers,
Chris
Adam Zilkie wrote:
Hi Chris,
I am having a problem similar to what you described in this discussion.
We are using the ppc arch with 2.6.24 with CONFIG_SEQUOIA with compiles
arch/ppc/kernel/head_44x.c (quite different
from /arch/powerpc/kernel/head_32.S). I would like to apply your
backporting patch to this architecture. Any help would be appreciated.
Regards,
Adam
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Fax. +44 1491 820001
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