Re: Reserving a fixed physical address page of RAM.

[Jon Ringle]

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.

Jon
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