[Linaro-mm-sig] Memory Management Discussion
jcrouse at codeaurora.org
Wed Apr 20 15:13:51 UTC 2011
On 04/19/2011 10:12 PM, Zach Pfeffer 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
> 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."
As we talked during the meeting at ELC, IOMMU is important, but I think that there
is broad agreement to consolidate (eventually) on the standard APIs. I still think
that the memory allocation problem is the more interesting one because it affects
everybody equally, MMU or not. Not that I want to shut down debate or anything,
I just don't want to distract us from the larger problem that we face.
> 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
>>> What we really need is a permanent solution (at upstream) which accommodates
>>> the following requirements and conforms to Graphics and Multimedia use
>>> 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
>>> 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..
>>> Linaro-mm-sig mailing list
>>> Linaro-mm-sig at lists.linaro.org
>> Linaro-mm-sig mailing list
>> Linaro-mm-sig at lists.linaro.org
> Linaro-mm-sig mailing list
> Linaro-mm-sig at lists.linaro.org
Qualcomm Innovation Center
Qualcomm Innovation Center is a member of Code Aurora Forum
More information about the Linaro-mm-sig