On Wed, 06 Jul 2011 18:05:00 +0200, Christoph Lameter <cl@xxxxxxxxx> wrote:
ZONE_DMA is a zone for memory of legacy (crippled) devices that cannot
DMA into all of memory (and so is ZONE_DMA32). Memory from ZONE_NORMAL
can be used for DMA as well and a fully capable device would be expected
to handle any memory in the system for DMA transfers.
"guaranteed" dmaable memory? DMA abilities are device specific. Well
maybe you can call ZONE_DMA memory to be guaranteed if you guarantee
that any device must at mininum be able to perform DMA into ZONE_DMA
memory. But there may not be much of that memory around so you would
want to limit the use of that scarce resource.
As pointed in Marek's other mail, this reasoning is not helping in any
way. In case of video codec on various Samsung devices (and from some
other threads this is not limited to Samsung), the codec needs separate
buffers in separate memory banks.
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