Skip to content

L
linux
Switch branch/tag
  1. 25 Sep, 2008 3 commits
    • FUJITA Tomonori's avatar
      x86: restore old GART alloc_coherent behavior · 1d990882
      FUJITA Tomonori authored 
      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: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      1d990882
    • FUJITA Tomonori's avatar
      revert "x86: make GART to respect device's dma_mask about virtual mappings" · ecef533e
      FUJITA Tomonori authored 
      This reverts:

commit bee44f29
Author: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Date:   Fri Sep 12 19:42:35 2008 +0900

    x86: make GART to respect device's dma_mask about virtual mappings

I wrote the above commit to fix a GART alloc_coherent regression, that
can't handle a device having dma_masks > 24bit < 32bits, introduced by
the alloc_coherent rewrite:

  http://lkml.org/lkml/2008/8/12/200

After the alloc_coherent rewrite, GART alloc_coherent tried to
allocate pages with GFP_DMA32. If GART got an address that a device
can't access to, GART mapped the address to a virtual I/O address. But
GART mapping mechanism didn't take account of dma mask, so GART could
use a virtual I/O address that the device can't access to again.

Alan pointed out:

" This is indeed a specific problem found with things like older
  AACRAID where control blocks must be below 31bits and the GART
  is above 0x80000000. "

The above commit modified GART mapping mechanism to take care of dma
mask. 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 means it's possible that GART doesn't have virtual I/O address
space that a device can access to. The above commit (to modify GART
mapping mechanism to take care of dma mask) can't fix the regression
reliably so let's avoid making GART more complicated.

We need a solution that always works for dma_masks > 24bit <
32bits. That's how GART worked before the alloc_coherent rewrite.
Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
Acked-by: default avatarAlan Cox <alan@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      ecef533e
    • FUJITA Tomonori's avatar
      x86: export pci-nommu's alloc_coherent · 9f6ac577
      FUJITA Tomonori authored 
      This patch exports nommu_alloc_coherent (renamed
dma_generic_alloc_coherent). GART needs this function.
Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      9f6ac577
  3. 22 Sep, 2008 3 commits
  5. 19 Sep, 2008 26 commits
  7. 14 Sep, 2008 6 commits
  9. 13 Sep, 2008 2 commits
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7