vijay baskar wrote:

Hi, "The kernel also allows hardcoded mapping of IO regions into its 
virtual address space through the io_block_mapping interface."

Can u tell me how this is in current arch/powerpc.

Everything is explicitly ioremapped.

Also does it mean that whatever be the size of the ram > 768 MB there
 is not going to be much improvement in performance in kernel space 
irrespective of invoking CONFIG_HIGHMEM or not?

Well, the kernel can use highmem for cache...  I'm not sure what you
mean by "in kernel space".

Also do you think this low mem be enough if i have lots of kernel 
space processes each invoking lots of kmallocs.

That depends on what you mean by "lots". :-)

You'll have 768MB of lowmem, and kmallocs can only use lowmem.

Will there be bottle necks?? Also what alternative do we have if  low
mem of 768 MB is not enough??

You'll need to change the user/kernel split, and deal with anything that 
breaks in the process.

Or get a 64-bit chip. :-)

-Scott