[PATCH 1/2] rtems: Add rtems_cache_coherent_allocate()

Sebastian Huber sebastian.huber at embedded-brains.de
Tue Dec 2 07:02:29 UTC 2014


Hello Daniel,

On 01/12/14 15:33, Daniel Hellstrom wrote:
> The coherent code looks nice and clean. I'm wondering, is it possbile 
> to add a memory region to the coherent area and at the same time make 
> malloc() return memory from that area when the default heap connected 
> to malloc() is empty? As I recall that is the behaviour of linux, when 
> the standard zone is empty it allocates from the DMA able memory zone 
> since it can do both. I would be interested in such an approach for 
> the LEON, where all memory can be used for the CPU but only 256MB of 
> memory can be accessed from the PCI. 

this should be possible.  One option is to allow a list of heaps instead 
of single RTEMS_Malloc_Heap.  The overhead seems to be acceptable too 
me.  It needs a bit of work and testing, probably more than a couple of 
hours.

-- 
Sebastian Huber, embedded brains GmbH

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