Can I page reserve memory allocated by kmalloc?
Marek
Arjan van de Ven wrote:
On Mon, 2005-12-12 at 03:26 -0500, Marek Olszewski wrote:
Hello, I'm doing a little project that investigates the benefits of
using the new (seemingly only accessible from privileged code) x86 SSE3
monitor/mwait instructions for locks on hyperthreaded machines.
To get this to work, I need to allocate some contiguous memory in kernel
space that is memory mapped to some address range in a userspace app.
For now, I'm just trying to get this to work by mmaping /dev/mem. I use
virt_to_phys on a kmalloced address and return it to my user app via a
syscall. I then try to mmap /dev/mem in my user app at an offset of the
returned address. The memory mapping seems to succeed, but when I check
the contents of the address (which I wrote to in kernel space), I don't
get a match. Is there some /dev/mem file location-to-physical memory
address mapping that I am not aware of? man mem says that they are the same.
mmap of non-PAGE_RESERVED kernel memory is not allowed, instead all
zeros are return.
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