Commit d69c7369 authored by Russell King's avatar Russell King

[ARM] Update ARM memory layout documentation.

This updates the memory layout documentation to indicate that certain
areas should remain unused.  It also corrects a few minor errors with
region end addresses.
parent 5d0e9fbf
Kernel Memory Layout on ARM Linux
Russell King <rmk@arm.linux.org.uk>
April 27, 2003 (2.5.68)
May 21, 2004 (2.6.6)
This document describes the virtual memory layout which the Linux
kernel uses for ARM processors. It indicates which regions are
......@@ -29,32 +29,30 @@ ffff0000 ffff0fff CPU vector page.
CPU supports vector relocation (control
register V bit.)
ffe00000 fffeffff Free for platform use, not recommended.
ffc00000 fffeffff DMA memory mapping region. Memory returned
by the dma_alloc_xxx functions will be
dynamically mapped here.
ffc00000 ffdfffff 2MB consistent memory mapping.
Memory returned by the consistent_alloc
low level function will be dynamically
mapped here.
ff000000 ffbfffff Reserved for future expansion of DMA
mapping region.
ff000000 ffbfffff Free for platform use, not recommended.
VMALLOC_END feffffff Free for platform use, recommended.
VMALLOC_END ff000000 Free for platform use, recommended.
VMALLOC_START VMALLOC_END vmalloc() / ioremap() space.
VMALLOC_START VMALLOC_END-1 vmalloc() / ioremap() space.
Memory returned by vmalloc/ioremap will
be dynamically placed in this region.
VMALLOC_START may be based upon the value
of the high_memory variable.
PAGE_OFFSET high_memory Kernel direct-mapped RAM region.
PAGE_OFFSET high_memory-1 Kernel direct-mapped RAM region.
This maps the platforms RAM, and typically
maps all platform RAM in a 1:1 relationship.
TASK_SIZE PAGE_OFFSET Kernel module space
TASK_SIZE PAGE_OFFSET-1 Kernel module space
Kernel modules inserted via insmod are
placed here using dynamic mappings.
00001000 TASK_SIZE User space mappings
00001000 TASK_SIZE-1 User space mappings
Per-thread mappings are placed here via
the mmap() system call.
......
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