path: root/include/asm-powerpc/pgtable-64k.h
diff options
authorPaul Mackerras <>2006-06-15 10:45:18 +1000
committerPaul Mackerras <>2006-06-15 10:45:18 +1000
commitbf72aeba2ffef599d1d386425c9e46b82be657cd (patch)
treeead8e5111dbcfa22e156999d1bb8a96e50f06fef /include/asm-powerpc/pgtable-64k.h
parent31925323b1b51bb65db729e029472a8b1f635b7d (diff)
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 <>
Diffstat (limited to 'include/asm-powerpc/pgtable-64k.h')
1 files changed, 2 insertions, 0 deletions
diff --git a/include/asm-powerpc/pgtable-64k.h b/include/asm-powerpc/pgtable-64k.h
index 653915014dcd..4b7126c53f37 100644
--- a/include/asm-powerpc/pgtable-64k.h
+++ b/include/asm-powerpc/pgtable-64k.h
@@ -90,6 +90,8 @@
#define pte_iterate_hashed_end() } while(0); } } while(0)
+#define pte_pagesize_index(pte) \
+ (((pte) & _PAGE_COMBO)? MMU_PAGE_4K: MMU_PAGE_64K)
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */