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| author | Jake Moilanen | 2007-03-29 15:44:02 +0200 |
|---|---|---|
| committer | Paul Mackerras | 2007-04-12 19:55:13 +0200 |
| commit | 569975591c5530fdc9c7a3c45122e5e46f075a74 (patch) | |
| tree | 47908de09d2e7d55d82a3b9d2e47b34b2c7f8133 /arch/powerpc/lib/copyuser_64.S | |
| parent | [POWERPC] Add uevent handler for of_platform_bus (diff) | |
| download | kernel-qcow2-linux-569975591c5530fdc9c7a3c45122e5e46f075a74.tar.gz kernel-qcow2-linux-569975591c5530fdc9c7a3c45122e5e46f075a74.tar.xz kernel-qcow2-linux-569975591c5530fdc9c7a3c45122e5e46f075a74.zip | |
[POWERPC] DMA 4GB boundary protection
There are many adapters which cannot handle DMAing across any 4 GB
boundary. For instance, the latest Emulex adapters.
This normally is not an issue as firmware gives dma-windows under
4gigs. However, some of the new System-P boxes have dma-windows above
4gigs, and this present a problem.
During initialization of the IOMMU tables, the last entry at each 4GB
boundary is marked as used. Thus no mappings can cross the boundary.
If a table ends at a 4GB boundary, the entry is not marked as used.
A boot option to remove this 4GB protection is given w/ protect4gb=off.
This exposes the potential issue for driver and hardware development
purposes.
Signed-off-by: Jake Moilanen <moilanen@austin.ibm.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/lib/copyuser_64.S')
0 files changed, 0 insertions, 0 deletions