Messages in this thread | | | From | "Pallipadi, Venkatesh" <> | Date | Thu, 18 Dec 2008 14:03:18 -0800 | Subject | RE: [patch 7/7] x86 PAT: update documentation to cover pgprot and remap_pfn related changes - v3 |
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>-----Original Message----- >From: Randy Dunlap [mailto:randy.dunlap@oracle.com] >Sent: Thursday, December 18, 2008 1:53 PM >To: Pallipadi, Venkatesh >Cc: mingo@elte.hu; tglx@linutronix.de; hpa@zytor.com; >akpm@linux-foundation.org; npiggin@suse.de; hugh@veritas.com; >arjan@infradead.org; jbarnes@virtuousgeek.org; >rdreier@cisco.com; jeremy@goop.org; >linux-kernel@vger.kernel.org; Siddha, Suresh B >Subject: Re: [patch 7/7] x86 PAT: update documentation to >cover pgprot and remap_pfn related changes - v3 > >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:
Sorry. Not sure how I missed it :( (note to self - do not send patches soon after lunch). Will promise to do all the changes as an incremental patch along with other comments.
Thanks, Venki
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