Kernel Memory Layout on ARM Linux
Russell King <rmk@arm.linux.org.uk>
- May 21, 2004 (2.6.6)
+ November 17, 2005 (2.6.15)
This document describes the virtual memory layout which the Linux
kernel uses for ARM processors. It indicates which regions are
For SA11xx and Xscale, this is used to
setup a minicache mapping.
+ffff4000 ffffffff cache aliasing on ARMv6 and later CPUs.
+
ffff1000 ffff7fff Reserved.
Platforms must not use this address range.
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.
mapping region.
VMALLOC_END feffffff Free for platform use, recommended.
+ VMALLOC_END must be aligned to a 2MB
+ boundary.
VMALLOC_START VMALLOC_END-1 vmalloc() / ioremap() space.
Memory returned by vmalloc/ioremap will
This maps the platforms RAM, and typically
maps all platform RAM in a 1:1 relationship.
-TASK_SIZE PAGE_OFFSET-1 Kernel module space
+PKMAP_BASE PAGE_OFFSET-1 Permanent kernel mappings
+ One way of mapping HIGHMEM pages into kernel
+ space.
+
+MODULES_VADDR MODULES_END-1 Kernel module space
Kernel modules inserted via insmod are
placed here using dynamic mappings.