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. -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
