x86: restore old GART alloc_coherent behavior

Browse source

Currently, GART alloc_coherent tries to allocate pages with GFP_DMA32
for a device having dma_masks > 24bit < 32bits. If GART gets an
address that a device can't access to, GART try to map the address to
a virtual I/O address that the device can access to.

But Andi pointed out, "The GART is somewhere in the 4GB range so you
cannot use it to map anything < 4GB. Also GART is pretty small."

http://lkml.org/lkml/2008/9/12/43

That is, it's possible that GART doesn't have virtual I/O address
space that a device can access to. The above behavior doesn't work for
a device having dma_masks > 24bit < 32bits.

This patch restores old GART alloc_coherent behavior (before the
alloc_coherent rewrite).

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

...

This commit is contained in:

FUJITA Tomonori 2008-09-24 20:48:37 +09:00 • committed by Ingo Molnar

parent ecef533ea6

commit 1d99088215

1 changed files with 20 additions and 23 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

37

arch/x86/kernel/pci-gart_64.c

View file