Messages in this thread Patch in this message | | | Date | Fri, 19 Dec 2008 13:47:30 -0800 | From | venkatesh.pallipadi@intel ... | Subject | [patch 5/5] x86 PAT: pfnmap documentation update changes |
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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>
--- Documentation/x86/pat.txt | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
Index: linux-2.6/Documentation/x86/pat.txt =================================================================== --- linux-2.6.orig/Documentation/x86/pat.txt 2008-12-19 09:55:04.000000000 -0800 +++ linux-2.6/Documentation/x86/pat.txt 2008-12-19 10:15:46.000000000 -0800 @@ -82,23 +82,23 @@ pci proc | -- | - 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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