* vmalloc and DMA
@ 2003-09-19 1:54 Stevie-O
2003-09-19 9:05 ` Alan Cox
0 siblings, 1 reply; 2+ messages in thread
From: Stevie-O @ 2003-09-19 1:54 UTC (permalink / raw)
To: linux-kernel
I need to treat a large number of pages (about 128) as continuous. However, I
need to DMA to that memory from a device. The device has a built-in
scatter-gather feature, so I don't need to worry about whether the pages are
physically contiguous. Looking through LXR revealed a function called
vmalloc_32. My questions are these:
(1) Is vmalloc_32 going to stick around for a while?
(2) Is it appropriate to vmalloc_32(512<<10) and then grab the underlying
addresses for DMA?
(3) If it *is* appropriate, what's the proper way to get to those underlying
addresses? I saw a virt_to_page macro somewhere...
--
- Stevie-O
Real Programmers use COPY CON PROGRAM.EXE
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: vmalloc and DMA
2003-09-19 1:54 vmalloc and DMA Stevie-O
@ 2003-09-19 9:05 ` Alan Cox
0 siblings, 0 replies; 2+ messages in thread
From: Alan Cox @ 2003-09-19 9:05 UTC (permalink / raw)
To: Stevie-O; +Cc: Linux Kernel Mailing List
On Gwe, 2003-09-19 at 02:54, Stevie-O wrote:
> I need to treat a large number of pages (about 128) as continuous.
Continuous to whom ?
> (2) Is it appropriate to vmalloc_32(512<<10) and then grab the underlying
> addresses for DMA?
> (3) If it *is* appropriate, what's the proper way to get to those underlying
> addresses? I saw a virt_to_page macro somewhere...
If you use the pci_alloc interfaces you'll get what you want except for
them not being fake contiguous to the kernel. You can still make them
contiguous to user space.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2003-09-19 1:54 vmalloc and DMA Stevie-O
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