Andrew Sterian wrote:
Hello all,
I'm developing a driver for an embedded ARM system (2.6.24 system) and
have 128M of RAM which I have been given free reign over. I want to
How do you define this free reign? Who is managing it ? kernel?
carve out an 8M block of RAM for use by this driver and mmap() it into
user space for transferring data from the driver to userspace.
I had faced a similar problem.
I have the driver working with 8k of RAM, simply using kmalloc(). My
efforts to scale up to 8M have failed.
1) kmalloc() won't work at 8M
2) get_free_pages() doesn't work -- says it can't fulfill a request of
the necessary order
3) I tried ioremap() -- didn't work
4) kmap() -- didn't work
5) vmalloc() -- didn't work
what I did was ioremap.
My case:
1. m/c had 256M
2. Passed parameter mem=128M to limit what cpu sees.
3. used ioremap on 0xc800_0000 (32bit processor) for 128M
4. used the returned virtual address.
Make sure that your PCI address space starts well above the physical
address present, so should the vmalloc_start address. I think you can
change #defines for these if required to suit your need.
Thanks,
Om.
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