Add documentation related to pgprot_* change.
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Suresh Siddha <[email protected]>
---
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 user 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, driver 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()
+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
--
On Thu, Dec 18, 2008 at 01:13:28PM -0800, Randy Dunlap wrote:
> [email protected] 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
Thanks,
Venki
Add documentation related to pgprot_* change.
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Suresh Siddha <[email protected]>
---
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
+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
+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
Pallipadi, Venkatesh wrote:
> On Thu, Dec 18, 2008 at 01:13:28PM -0800, Randy Dunlap wrote:
>> [email protected] 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 <[email protected]>
> Signed-off-by: Suresh Siddha <[email protected]>
> ---
> 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
>-----Original Message-----
>From: Randy Dunlap [mailto:[email protected]]
>Sent: Thursday, December 18, 2008 1:53 PM
>To: Pallipadi, Venkatesh
>Cc: [email protected]; [email protected]; [email protected];
>[email protected]; [email protected]; [email protected];
>[email protected]; [email protected];
>[email protected]; [email protected];
>[email protected]; 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:
>>> [email protected] 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
[email protected] 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.
--
~Randy