diff options
| author | Paul Mackerras <paulus@samba.org> | 2006-06-15 10:45:18 +1000 |
|---|---|---|
| committer | Paul Mackerras <paulus@samba.org> | 2006-06-15 10:45:18 +1000 |
| commit | bf72aeba2ffef599d1d386425c9e46b82be657cd (patch) | |
| tree | ead8e5111dbcfa22e156999d1bb8a96e50f06fef /arch/powerpc/kernel/prom.c | |
| parent | 31925323b1b51bb65db729e029472a8b1f635b7d (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 <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/kernel/prom.c')
| -rw-r--r-- | arch/powerpc/kernel/prom.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c index 969f4abcc0be..d77d24a89b39 100644 --- a/arch/powerpc/kernel/prom.c +++ b/arch/powerpc/kernel/prom.c @@ -948,7 +948,10 @@ static struct ibm_pa_feature { {CPU_FTR_CTRL, 0, 0, 3, 0}, {CPU_FTR_NOEXECUTE, 0, 0, 6, 0}, {CPU_FTR_NODSISRALIGN, 0, 1, 1, 1}, +#if 0 + /* put this back once we know how to test if firmware does 64k IO */ {CPU_FTR_CI_LARGE_PAGE, 0, 1, 2, 0}, +#endif }; static void __init check_cpu_pa_features(unsigned long node) |