Re: [RFC PATCH 3/3] mm/map_contig: Add mmap(MAP_CONTIG) support

[Laura Abbott]

On 10/16/2017 01:32 PM, Mike Kravetz wrote:
> On 10/16/2017 11:07 AM, Michal Hocko wrote:
>> On Mon 16-10-17 10:43:38, Mike Kravetz wrote:
>>> Just to be clear, the posix standard talks about a typed memory object.
>>> The suggested implementation has one create a connection to the memory
>>> object to receive a fd, then use mmap as usual to get a mapping backed
>>> by contiguous pages/memory.  Of course, this type of implementation is
>>> not a requirement.
>>
>> I am not sure that POSIC standard for typed memory is easily
>> implementable in Linux. Does any OS actually implement this API?
> 
> A quick search only reveals Blackberry QNX and PlayBook OS.
> 
> Also somewhat related.  In a earlier thread someone pointed out this
> out of tree module used for contiguous allocations in SOC (and other?)
> environments.  It even has the option of making use of CMA.
> http://processors.wiki.ti.com/index.php/CMEM_Overview
> 

If we're at the point where we're discussing CMEM, I'd like to
point out that ion (drivers/staging/android/ion) already provides an
ioctl interface to allocate CMA and other types of memory. It's
mostly used for Android as the name implies. I don't pretend the
interface is perfect but it could be useful as a discussion point
for allocation interfaces.

Thanks,
Laura