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From: Zhu, Yijun (NSN - CN/Beijing) on 8 Mar 2010 03:10

Hi All:

I try to alloc 4M memory for the DMA purpose in the 256M system running
V2.6.29. But failed.

I check the system, there is no 4M DMA memory in the DMA zone free list
indeed, So I'd like to
ask for that Is it possible for me to alloc 4M(or larger) DMA memory in
the linux system.
if YES, HOW?

I forgot to say my hardware is based on X86.

Thank you in advance.
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From: Mark Hounschell on 10 Mar 2010 06:00
Zhu, Yijun (NSN - CN/Beijing) wrote:
>
> Hi All:
>
> I try to alloc 4M memory for the DMA purpose in the 256M system running
> V2.6.29. But failed.
>
> I check the system, there is no 4M DMA memory in the DMA zone free list
> indeed, So I'd like to
> ask for that Is it possible for me to alloc 4M(or larger) DMA memory in
> the linux system.
> if YES, HOW?
>
> I forgot to say my hardware is based on X86.
>
> Thank you in advance.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo(a)vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>

There is still a bigphysarea patch around that works for me. (attached) I
know of no other way using the hardware I need to do it with. IE, no
scatter/gather capabilities so memory must be contiguous. I personally
haven't used it with more than 2M but it should work.

Regards
Mark
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