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author | Paul Mackerras <paulus@samba.org> | 2006-06-15 10:45:18 +1000 |
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committer | Paul Mackerras <paulus@samba.org> | 2006-06-15 10:45:18 +1000 |
commit | bf72aeba2ffef599d1d386425c9e46b82be657cd (patch) | |
tree | ead8e5111dbcfa22e156999d1bb8a96e50f06fef /include/asm-powerpc/pgtable-4k.h | |
parent | 31925323b1b51bb65db729e029472a8b1f635b7d (diff) | |
download | op-kernel-dev-bf72aeba2ffef599d1d386425c9e46b82be657cd.zip op-kernel-dev-bf72aeba2ffef599d1d386425c9e46b82be657cd.tar.gz |
powerpc: Use 64k pages without needing cache-inhibited large pages
Some POWER5+ machines can do 64k hardware pages for normal memory but
not for cache-inhibited pages. This patch lets us use 64k hardware
pages for most user processes on such machines (assuming the kernel
has been configured with CONFIG_PPC_64K_PAGES=y). User processes
start out using 64k pages and get switched to 4k pages if they use any
non-cacheable mappings.
With this, we use 64k pages for the vmalloc region and 4k pages for
the imalloc region. If anything creates a non-cacheable mapping in
the vmalloc region, the vmalloc region will get switched to 4k pages.
I don't know of any driver other than the DRM that would do this,
though, and these machines don't have AGP.
When a region gets switched from 64k pages to 4k pages, we do not have
to clear out all the 64k HPTEs from the hash table immediately. We
use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page
was hashed in as a 64k page or a set of 4k pages. If hash_page is
trying to insert a 4k page for a Linux PTE and it sees that it has
already been inserted as a 64k page, it first invalidates the 64k HPTE
before inserting the 4k HPTE. The hash invalidation routines also use
the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a
set of 4k HPTEs to remove. With those two changes, we can tolerate a
mix of 4k and 64k HPTEs in the hash table, and they will all get
removed when the address space is torn down.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'include/asm-powerpc/pgtable-4k.h')
-rw-r--r-- | include/asm-powerpc/pgtable-4k.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/asm-powerpc/pgtable-4k.h b/include/asm-powerpc/pgtable-4k.h index b2e1862..e703615 100644 --- a/include/asm-powerpc/pgtable-4k.h +++ b/include/asm-powerpc/pgtable-4k.h @@ -78,6 +78,8 @@ #define pte_iterate_hashed_end() } while(0) +#define pte_pagesize_index(pte) MMU_PAGE_4K + /* * 4-level page tables related bits */ |