On Wed, Jan 21, 2004 at 03:58:24PM -0600, Nils Larson wrote:
> We currently have a mips platform running Linux with 256MB of
> RAM starting at 0x8000_0000. We would like to add an additional
> 1GB of RAM, maybe starting at 0x4000_0000, that would be used
> for user apps (user virtual memory). The memory map is:
> 0x8000_0000 - 256MB RAM
> 0xA000_0000 - uncached version of the same 256MB
> 0xB000_0000 - PCI memory windows.
> This is a diskless setup booting from a ramdisk.
> So, the (sort of newbie) questions are:
> 1. How do we tell Linux to use the new memory?
> 2. Is this feasible?
> 3. Is there a better way to add more memory?
> We need more space for user data.
People have done this before in 2.4 with CONFIG_HIGHMEM.
See arch/mips/sibyte/cfe/setup.c for more details.
However, if the CPU suffers from virtual aliasing problem, I
think this won't work at all.
I think that is pretty much only way to get more RAM
in 32bit system. With 64bit kernel of course you don't have
any problems at all.