* uio and DMA memory allocations
@ 2006-12-17 15:04 Gleb Natapov
2006-12-17 18:16 ` Hans-Jürgen Koch
0 siblings, 1 reply; 2+ messages in thread
From: Gleb Natapov @ 2006-12-17 15:04 UTC (permalink / raw)
To: hjk; +Cc: linux-kernel
Hi Hans,
Will it be possible to allocate DMAable memory using uio framework
(currently it isn't as far as I see). More specifically if a driver needs
memory allocated with dma_alloc_coherent() will it be possible to allocate
it and map into userspace using uio?
--
Gleb.
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: uio and DMA memory allocations
2006-12-17 15:04 uio and DMA memory allocations Gleb Natapov
@ 2006-12-17 18:16 ` Hans-Jürgen Koch
0 siblings, 0 replies; 2+ messages in thread
From: Hans-Jürgen Koch @ 2006-12-17 18:16 UTC (permalink / raw)
To: Gleb Natapov; +Cc: linux-kernel
Am Sonntag, 17. Dezember 2006 16:04 schrieb Gleb Natapov:
> Hi Hans,
>
> Will it be possible to allocate DMAable memory using uio
> framework (currently it isn't as far as I see). More specifically
> if a driver needs memory allocated with dma_alloc_coherent() will
> it be possible to allocate it and map into userspace using uio?
Hi Gleb,
I didn't write such a driver yet, but it is certainly possible.
As a first thought, I think we need a small change in the uio
framework mmap routine. AFAIK, dma_alloc_coherent() returns a
kernel virtual address that would not be handled properly by
the existing code. At the moment, we only have the choice between
logical and physical memory, we probably have to add virtual
memory, too. Thanks for that hint, I'll keep it in mind.
Hans
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2006-12-17 15:04 uio and DMA memory allocations Gleb Natapov
2006-12-17 18:16 ` Hans-Jürgen Koch
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