Merge tag 'cris-for-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/jesper...

[cascardo/linux.git] / Documentation / xtensa / mmu.txt

diff --git a/Documentation/xtensa/mmu.txt b/Documentation/xtensa/mmu.txt
index 867c0f8..222a2c6 100644 (file)
--- a/Documentation/xtensa/mmu.txt
+++ b/Documentation/xtensa/mmu.txt
@@ -3,15 +3,8 @@ MMUv3 initialization sequence.
 The code in the initialize_mmu macro sets up MMUv3 memory mapping
 identically to MMUv2 fixed memory mapping. Depending on
 CONFIG_INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX symbol this code is
-located in one of the following address ranges:
-
-    0xF0000000..0xFFFFFFFF (will keep same address in MMU v2 layout;
-                        typically ROM)
-    0x00000000..0x07FFFFFF (system RAM; this code is actually linked
-                        at 0xD0000000..0xD7FFFFFF [cached]
-                        or 0xD8000000..0xDFFFFFFF [uncached];
-                        in any case, initially runs elsewhere
-                        than linked, so have to be careful)
+located in addresses it was linked for (symbol undefined), or not
+(symbol defined), so it needs to be position-independent.
 
 The code has the following assumptions:
   This code fragment is run only on an MMU v3.
@@ -28,24 +21,26 @@ TLB setup proceeds along the following steps.
     PA = physical address (two upper nibbles of it);
     pc = physical range that contains this code;
 
-After step 2, we jump to virtual address in 0x40000000..0x5fffffff
-that corresponds to next instruction to execute in this code.
-After step 4, we jump to intended (linked) address of this code.
-
-    Step 0     Step1     Step 2     Step3     Step 4     Step5
- ============  =====  ============  =====  ============  =====
-   VA      PA     PA    VA      PA     PA    VA      PA     PA
- ------    --     --  ------    --     --  ------    --     --
- E0..FF -> E0  -> E0  E0..FF -> E0         F0..FF -> F0  -> F0
- C0..DF -> C0  -> C0  C0..DF -> C0         E0..EF -> F0  -> F0
- A0..BF -> A0  -> A0  A0..BF -> A0         D8..DF -> 00  -> 00
- 80..9F -> 80  -> 80  80..9F -> 80         D0..D7 -> 00  -> 00
- 60..7F -> 60  -> 60  60..7F -> 60
- 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
+After step 2, we jump to virtual address in the range 0x40000000..0x5fffffff
+or 0x00000000..0x1fffffff, depending on whether the kernel was loaded below
+0x40000000 or above. That address corresponds to next instruction to execute
+in this code. After step 4, we jump to intended (linked) address of this code.
+The scheme below assumes that the kernel is loaded below 0x40000000.
+
+        Step0  Step1  Step2  Step3          Step4  Step5
+        =====  =====  =====  =====          =====  =====
+   VA      PA     PA     PA     PA     VA      PA     PA
+ ------    --     --     --     --   ------    --     --
+ E0..FF -> E0  -> E0  -> E0          F0..FF -> F0  -> F0
+ C0..DF -> C0  -> C0  -> C0          E0..EF -> F0  -> F0
+ A0..BF -> A0  -> A0  -> A0          D8..DF -> 00  -> 00
+ 80..9F -> 80  -> 80  -> 80          D0..D7 -> 00  -> 00
+ 60..7F -> 60  -> 60  -> 60
+ 40..5F -> 40         -> pc  -> pc   40..5F -> pc
+ 20..3F -> 20  -> 20  -> 20
+ 00..1F -> 00  -> 00  -> 00
+
+The default location of IO peripherals is above 0xf0000000. This may be changed
 using a "ranges" property in a device tree simple-bus node. See ePAPR 1.1, §6.5
 for details on the syntax and semantic of simple-bus nodes. The following
 limitations apply: