* How to guarantee that kmalloc returns an address below 4GB
@ 2007-05-16 8:30 Cestonaro, Thilo (external)
2007-05-16 13:11 ` Stefan Richter
0 siblings, 1 reply; 3+ messages in thread
From: Cestonaro, Thilo (external) @ 2007-05-16 8:30 UTC (permalink / raw)
To: linux-kernel
Hey,
is there an option for kmalloc, which I can use to allocate a buffer which is in physical memory placed below 4GB?
Not in a remapped area.
The only way I found is to use GFP_DMA, but this says the first 16MB isn't it?
Ciao Thilo
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: How to guarantee that kmalloc returns an address below 4GB
2007-05-16 8:30 How to guarantee that kmalloc returns an address below 4GB Cestonaro, Thilo (external)
@ 2007-05-16 13:11 ` Stefan Richter
2007-05-17 18:46 ` Christoph Lameter
0 siblings, 1 reply; 3+ messages in thread
From: Stefan Richter @ 2007-05-16 13:11 UTC (permalink / raw)
To: Cestonaro, Thilo (external); +Cc: linux-kernel
Cestonaro, Thilo (external) wrote:
> is there an option for kmalloc, which I can use to allocate
> a buffer which is in physical memory placed below 4GB?
> Not in a remapped area.
GFP_DMA32
http://lxr.linux.no/source/include/linux/gfp.h#L82
--
Stefan Richter
-=====-=-=== -=-= =----
http://arcgraph.de/sr/
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: How to guarantee that kmalloc returns an address below 4GB
2007-05-16 13:11 ` Stefan Richter
@ 2007-05-17 18:46 ` Christoph Lameter
0 siblings, 0 replies; 3+ messages in thread
From: Christoph Lameter @ 2007-05-17 18:46 UTC (permalink / raw)
To: Stefan Richter; +Cc: Cestonaro, Thilo (external), linux-kernel
On Wed, 16 May 2007, Stefan Richter wrote:
> Cestonaro, Thilo (external) wrote:
> > is there an option for kmalloc, which I can use to allocate
> > a buffer which is in physical memory placed below 4GB?
> > Not in a remapped area.
>
> GFP_DMA32
Nope. There are no general slabs available for DMA32.
You could use a dma slab by specifying GFP_DMA. However, on i386 and
x86_64 this will get you memory in the precious first 16MB. On IA64 and
other platforms you will get memory < 4GB.
Another option is to use the page allocator and specify GFP_DMA32.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2007-05-16 8:30 How to guarantee that kmalloc returns an address below 4GB Cestonaro, Thilo (external)
2007-05-16 13:11 ` Stefan Richter
2007-05-17 18:46 ` Christoph Lameter
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