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authorvenkatesh.pallipadi@intel.com <venkatesh.pallipadi@intel.com>2008-12-19 13:47:30 -0800
committerH. Peter Anvin <hpa@zytor.com>2008-12-19 15:40:31 -0800
commit67bac792cd0c05b4b6e0393c32605b028b8dd533 (patch)
tree03e978a671180abbd634e40add6a29b1887334ca /Documentation/x86/pat.txt
parent34801ba9bf0381fcf0e2b08179d2c07f2c6ede74 (diff)
x86: PAT: pfnmap documentation update changes
Impact: Documentation only. Documentation updates as per Randy Dunlap's comments. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'Documentation/x86/pat.txt')
-rw-r--r--Documentation/x86/pat.txt10
1 files changed, 5 insertions, 5 deletions
diff --git a/Documentation/x86/pat.txt b/Documentation/x86/pat.txt
index 1784ff276997..cf08c9fff3cd 100644
--- a/Documentation/x86/pat.txt
+++ b/Documentation/x86/pat.txt
@@ -82,23 +82,23 @@ pci proc | -- | -- | WC |
Advanced APIs for drivers
-------------------------
-A. Exporting pages to user with remap_pfn_range, io_remap_pfn_range,
+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
+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, driver can
+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 work with IO (non RAM) regions. If driver
-wants to export RAM region, it has to do set_memory_uc() or set_memory_wc()
+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.

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