Messages in this thread | | | Date | Thu, 18 Dec 2008 13:53:14 -0800 | From | Randy Dunlap <> | Subject | Re: [patch 7/7] x86 PAT: update documentation to cover pgprot and remap_pfn related changes - v3 |
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Pallipadi, Venkatesh wrote: > On Thu, Dec 18, 2008 at 01:13:28PM -0800, Randy Dunlap wrote: >> venkatesh.pallipadi@intel.com wrote: >> >> +Advanced APIs for drivers >> +------------------------- >> +A. Exporting pages to user with remap_pfn_range, io_remap_pfn_range, >> >> to users >> or to userspace >> >> +vm_insert_pfn >> + >> +Drivers wanting to export some pages to userspace, do it by using mmap >> >> Drop comma. >> >> +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 >> >> s/pat/PAT/ >> s/driver/drivers/ or s/driver/a driver/ >> >> +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 >> >> works with IO (non-RAM) regions. If a driver >> >> +wants to export RAM region, it has to do set_memory_uc() or set_memory_wc() >> >> export a RAM region, >> >> +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. >> >> > > refreshed patch below
Some of them were changed, others not changed, with no explanation... More changes below:
> Thanks, > Venki > > > Add documentation related to pgprot_* change. > > Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> > Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> > --- > Documentation/x86/pat.txt | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > Index: linux-2.6/Documentation/x86/pat.txt > =================================================================== > --- linux-2.6.orig/Documentation/x86/pat.txt 2008-12-17 15:01:50.000000000 -0800 > +++ linux-2.6/Documentation/x86/pat.txt 2008-12-17 17:23:16.000000000 -0800 > @@ -80,6 +80,30 @@ pci proc | -- | - > | | | | > ------------------------------------------------------------------- > > +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
PAT (please)
> +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 a driver
only works with IO (non-RAM)
> +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.
-- ~Randy
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