Re: use of alloc_bootmem for a PCI-e device

["Michal Nazarewicz" <mina86@mina86.com>]

> On Nov 23, 2011, at 14:31, Michal Nazarewicz wrote:
>> One trick that you might try to use (even though it's a bit hackish) is to
>> pass ram=### on Linux command line where the number passed is actual memory
>> minus size of the buffer you need.  Other then that, you might take a look
>> at CMA (CMAv17 it was sent last week or so to linux-mm) which in one of the
>> initialisation steps needs to grab memory regions.

On Wed, 23 Nov 2011 22:21:15 +0100, Jean-Francois Dagenais <jeff.dagenais@gmail.com> wrote:
> Looks like it can do what I want. Are there any mainline merge plans?

There are plans...  Execution is uncertain. ;)

> Unless I am mistaken, because of SWIOTLB, only x86_32 is supported, correct?
>
> Since I want to allocate the buffer once at startup, then keep it until shutdown,
> can you suggest a simpler, less flexible alternative?

Oh no, I wouldn't recommend using the full CMA for your purpose, but no matter
there is a piece of code that does what you need.  Marek has added support for
Intel so it should work for you as well, even though I have had a chance to
run that piece yet.

You are interested in parts of patch 8[1] (namely dma_declare_contiguous()
function) and the last hunk of patch 9[2] (namely the part where
dma_contiguous_reserve() is called).

[1] http://article.gmane.org/gmane.linux.kernel.mm/70321
[2] http://article.gmane.org/gmane.linux.kernel.mm/70318

-- 
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