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| author | Nicolas Pitre <nico@cam.org> | 2008-09-16 19:05:53 +0200 |
|---|---|---|
| committer | Nicolas Pitre <nico@cam.org> | 2009-03-16 02:01:20 +0100 |
| commit | 5f0fbf9ecaf354fa4bbf266fffdea2ea3d14a0ed (patch) | |
| tree | 9f0c59760b2bec510519118ddb17d4b15db473f5 /Documentation/arm/memory.txt | |
| parent | [ARM] Fix virtual to physical translation macro corner cases (diff) | |
| download | linux-5f0fbf9ecaf354fa4bbf266fffdea2ea3d14a0ed.tar.xz linux-5f0fbf9ecaf354fa4bbf266fffdea2ea3d14a0ed.zip | |
[ARM] fixmap support
This is the minimum fixmap interface expected to be implemented by
architectures supporting highmem.
We have a second level page table already allocated and covering
0xfff00000-0xffffffff because the exception vector page is located
at 0xffff0000, and various cache tricks already use some entries above
0xffff0000. Therefore the PTEs covering 0xfff00000-0xfffeffff are free
to be used.
However the XScale cache flushing code already uses virtual addresses
between 0xfffe0000 and 0xfffeffff.
So this reserves the 0xfff00000-0xfffdffff range for fixmap stuff.
The Documentation/arm/memory.txt information is updated accordingly,
including the information about the actual top of DMA memory mapping
region which didn't match the code.
Signed-off-by: Nicolas Pitre <nico@marvell.com>
Diffstat (limited to 'Documentation/arm/memory.txt')
| -rw-r--r-- | Documentation/arm/memory.txt | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/Documentation/arm/memory.txt b/Documentation/arm/memory.txt index dc6045577a8b..43cb1004d35f 100644 --- a/Documentation/arm/memory.txt +++ b/Documentation/arm/memory.txt @@ -29,7 +29,14 @@ ffff0000 ffff0fff CPU vector page. CPU supports vector relocation (control register V bit.) -ffc00000 fffeffff DMA memory mapping region. Memory returned +fffe0000 fffeffff XScale cache flush area. This is used + in proc-xscale.S to flush the whole data + cache. Free for other usage on non-XScale. + +fff00000 fffdffff Fixmap mapping region. Addresses provided + by fix_to_virt() will be located here. + +ffc00000 ffefffff DMA memory mapping region. Memory returned by the dma_alloc_xxx functions will be dynamically mapped here. |