[Linaro-mm-sig] Memory Management Discussion

[Kyungmin Park]

On Wed, Apr 20, 2011 at 1:30 PM, Zach Pfeffer <zach.pfeffer at linaro.org> wrote:
> Yeah. I wanted to list VCMM it since it seemed to get a lot of
> feedback. It did everything wrong and seemed to generate a lot of "you
> should do it this way" traffic, which should help the unified memory
> manager discussion.

Now we're working on the suggested method, DMA APIs for IOMMUs. So can
you discuss it together?
http://www.spinics.net/lists/linux-media/msg31524.html

>
> On 19 April 2011 23:19, Kyungmin Park <kmpark at infradead.org> wrote:
>> Please see the following URLs
>> https://lkml.org/lkml/2011/4/19/172
>>
>> We (Me, Michal, Marek) tried it based on yours. but some peoples
>> doesn't like it.
>>
>> Thank you,
>> Kyungmin Park
>>
>> On Wed, Apr 20, 2011 at 1:12 PM, Zach Pfeffer <zach.pfeffer at linaro.org> wrote:
>>> Speaking of Graphics and Multimedia - we may want to discuss IOMMU
>>> APIs and distributed memory management. These devices are becoming
>>> more prevalent and having a standard way of working with them would be
>>> useful.
>>>
>>> I did a little of this work at Qualcomm and pushed some soundly
>>> rejected patches to the kernel, see "mm: iommu: An API to unify IOMMU,
>>> CPU and device memory management."
>>>
>>> -Zach
>>>
>>> On 19 April 2011 20:52, Clark, Rob <rob at ti.com> wrote:
>>>> On Mon, Apr 18, 2011 at 9:45 AM, Sree Kumar <sreeon at gmail.com> wrote:
>>>>> Thanks Jesse for initiating the mailing list.
>>>>>
>>>>> We need to address the requirements of Graphics and Multimedia Accelerators
>>>>> (IPs).
>>>>> What we really need is a permanent solution (at upstream) which accommodates
>>>>> the following requirements and conforms to Graphics and Multimedia use
>>>>> cases.
>>>>>
>>>>> 1.Mechanism to map/unmap the memory. Some of the IPs’ have the ability to
>>>>> address virtual memory and some can address only physically contiguous
>>>>> address space. We need to address both these cases.
>>>>> 2.Mechanism to allocate and release memory.
>>>>> 3.Method to share the memory (ZERO copy is a MUST for better performance)
>>>>> between different device drivers (example output of camera to multimedia
>>>>> encoder).
>>>>> 4.Method to share the memory with different processes in userspace. The
>>>>> sharing mechanism should include built-in security features.
>>>>>
>>>>> Are there any special requirements from V4L or DRM perspectives?
>>>>
>>>> From DRI perspective.. I guess the global buffer name is restricted to
>>>> a 4 byte integer, unless you change the DRI proto..
>>>>
>>>> Authentication hooks for the driver (on x11 driver side) are for a
>>>> single authentication covering all buffers shared between client and
>>>> server, and is done by 4 byte token exchange between client and
>>>> server.  I've not had time yet to look more closely at the
>>>> authentication aspect of ION.
>>>>
>>>> Those are just things off the top of my head, hopefully someone else
>>>> from X11 world chimes in with whatever else I missed.  But I guess
>>>> most important thing is whether or not it can fit within existing DRI
>>>> protocol.  If it does, then the drivers on client and server side
>>>> could use whatever..
>>>>
>>>> BR,
>>>> -R
>>>>
>>>>
>>>>> Thanks,
>>>>> Sree
>>>>>
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>>>>>
>>>>>
>>>>
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>>
>