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authorLachlan McIlroy <lachlan@redback.melbourne.sgi.com>2008-12-29 16:47:18 +1100
committerLachlan McIlroy <lachlan@redback.melbourne.sgi.com>2008-12-29 16:47:18 +1100
commit0a8c5395f90f06d128247844b2515c8bf3f2826b (patch)
treed95382dcdfa303b99d480c01763d6cb6767fdaca /Documentation/x86/pat.txt
parent25051158bbed127e8672b43396c71c5eb610e5f1 (diff)
parent3c92ec8ae91ecf59d88c798301833d7cf83f2179 (diff)
downloadop-kernel-dev-0a8c5395f90f06d128247844b2515c8bf3f2826b.zip
op-kernel-dev-0a8c5395f90f06d128247844b2515c8bf3f2826b.tar.gz
[XFS] Fix merge failures
Merge git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 Conflicts: fs/xfs/linux-2.6/xfs_cred.h fs/xfs/linux-2.6/xfs_globals.h fs/xfs/linux-2.6/xfs_ioctl.c fs/xfs/xfs_vnodeops.h Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Diffstat (limited to 'Documentation/x86/pat.txt')
-rw-r--r--Documentation/x86/pat.txt24
1 files changed, 24 insertions, 0 deletions
diff --git a/Documentation/x86/pat.txt b/Documentation/x86/pat.txt
index c93ff5f..cf08c9f 100644
--- a/Documentation/x86/pat.txt
+++ b/Documentation/x86/pat.txt
@@ -80,6 +80,30 @@ pci proc | -- | -- | WC |
| | | |
-------------------------------------------------------------------
+Advanced APIs for drivers
+-------------------------
+A. Exporting pages to users with remap_pfn_range, io_remap_pfn_range,
+vm_insert_pfn
+
+Drivers wanting to export some pages to userspace do it by using mmap
+interface and a combination of
+1) pgprot_noncached()
+2) io_remap_pfn_range() or remap_pfn_range() or vm_insert_pfn()
+
+With PAT support, a new API pgprot_writecombine is being added. So, drivers can
+continue to use the above sequence, with either pgprot_noncached() or
+pgprot_writecombine() in step 1, followed by step 2.
+
+In addition, step 2 internally tracks the region as UC or WC in memtype
+list in order to ensure no conflicting mapping.
+
+Note that this set of APIs only works with IO (non RAM) regions. If driver
+wants to export a RAM region, it has to do set_memory_uc() or set_memory_wc()
+as step 0 above and also track the usage of those pages and use set_memory_wb()
+before the page is freed to free pool.
+
+
+
Notes:
-- in the above table mean "Not suggested usage for the API". Some of the --'s
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