256MB Flash and 512MB SDRAM - out of vmalloc space
chris.elston at radstone.co.uk
Thu Mar 31 08:10:23 EST 2005
I've encountered a fairly fundamental problem with my Flash mapping driver,
and I was hoping that someone could check my proposed solution for sanity:
I have a board with 512MB SDRAM and 256MB of Flash. The SDRAM eats up a
big chunk of kernel virtual addresses and therefore mapping the Flash with
ioremap fails because I've run out of contiguous virtual address space.
I can't reserve more space with a "vmem=xxx" commandline because I'm on ppc
not x86. I don't really want to go down that route anyway, because my
company will eventually produce boards with 1GB SDRAM, which will only make
My proposed solution is to use the read/write and copy_from/copy_to hooks in
the map_info struct to provide access to the device through a window. This
would obviously only apply to my board, but I'm thinking that as memory
sizes and Flash sizes increase this problem will become more common. Should
I implement this in the main MTD code? If so, has anyone any preferences
for how I do it?
Alternatively, I've completely missed the point and there's already a way to
do this, but I couldn't see anything in any of the other mapping drivers.
PS: David, I've submitted a request to our IT dept for IMAP access to our
<spit> exchange server </spit> so I can use a less proprietary mail client.
Principal Software Engineer, Processor Group
Radstone Digital Processing
Tove Valley Business Park
Direct Line: +44-(0)1327-322876
mailto:chris.elston at radstone.com
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