Jon Ringle wrote:
Robert Hancock wrote:
Jon Ringle wrote:
Hi,
I need to reserve a page of memory at a specific area of RAM that will
be used as a "shared memory" with another processor over PCI. How can I
ensure that the this area of RAM gets reseved so that the Linux's memory
management (kmalloc() and friends) don't use it?
Some things that I've considered are iotable_init() and ioremap().
However, I've seen these used for memory mapped IO devices which are
outside of the RAM memory. Can I use them for reseving RAM too?
I appreciate any advice in this regard.
Sounds to me like dma_alloc_coherent is what you want..
It looks promising, however, I need to reserve a physical address area
that is well known (so that the code running on the other processor
knows where in PCI memory to write to). It appears that
dma_alloc_coherent returns the address that it allocated. Instead I need
something where I can tell it what physical address and range I want to
use.
I don't think this is possible in the general case, as there's no
mechanism for moving things out of the way if they might be in use. Your
best solution is likely to use dma_alloc_coherent and pass the bus
address returned into the other processor to tell it where to write..
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from [email protected]
Home Page: http://www.roberthancock.com/
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