Hi Prabhu,

On Tue, Jul 10, 2012 at 6:56 AM, Prabhu nath [off-list ref] wrote:

For E.g. I have a device whose physical address range is 0x80008000 to
0x80008FFF.
             Is it possible to map this device physical address to a known
virtual address range 0xF0008000 to 0xF0008FFF.

I don't think this is possible, because these virtual address ranges
are handled by the kernel VMA system and are allocated dynamically, so
that is not just a bitmask or something to change.

My hardware configuration has 128 MB of system RAM which will have been
MAPPED to the Kernel virtual address from 0xC0000000 to 0xC7FFFFFF

Also is it possible to configure the vmalloc kernel virtual address region
to a fixed range of 128 MB from 0xC8000000 to 0xCFFFFFFF

You could change PAGE_OFFSET. From [1]:


PHYS_OFFSET
	Physical start address of the first bank of RAM.

PAGE_OFFSET
	Virtual start address of the first bank of RAM.  During the kernel
	boot phase, virtual address PAGE_OFFSET will be mapped to physical
	address PHYS_OFFSET, along with any other mappings you supply.
	This should be the same value as TASK_SIZE.


But I'm curious: Why do you want to change it?


Greetings,

  Philipp


[1]: http://www.kernelport.org/defines.html