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Diffstat (limited to 'Documentation/xtensa')
| -rw-r--r-- | Documentation/xtensa/mmu.txt | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/xtensa/mmu.txt b/Documentation/xtensa/mmu.txt index 2b1af7606d57..0312fe66475c 100644 --- a/Documentation/xtensa/mmu.txt +++ b/Documentation/xtensa/mmu.txt @@ -44,3 +44,21 @@ After step 4, we jump to intended (linked) address of this code. 40..5F -> 40 40..5F -> pc -> pc 40..5F -> pc 20..3F -> 20 -> 20 20..3F -> 20 00..1F -> 00 -> 00 00..1F -> 00 + +The default location of IO peripherals is above 0xf0000000. This may change +using a "ranges" property in a device tree simple-bus node. See ePAPR 1.1, ยง6.5 +for details on the syntax and semantic of simple-bus nodes. The following +limitations apply: + +1. Only top level simple-bus nodes are considered + +2. Only one (first) simple-bus node is considered + +3. Empty "ranges" properties are not supported + +4. Only the first triplet in the "ranges" property is considered + +5. The parent-bus-address value is rounded down to the nearest 256MB boundary + +6. The IO area covers the entire 256MB segment of parent-bus-address; the + "ranges" triplet length field is ignored |