Hi Prabhu, On Tue, Oct 26, 2010 at 9:19 PM, Prabhu nath <[email protected]> wrote: > Dear All, > > Can you please clarify my doubt on /dev/mem > > When I open /dev/mem, Is that entire physical address space is > associated to /dev/mem or only the system memory ? > * If I can mmap the kernel memory in read write mode, I can screw > up the whole kernel. Is that right ?
Absolutely. > * Suppose I map a random memory page frame (let's assume it is a > free page) from physical address 1abde000 to 1abdf000, > then will the page allocator not allocate this page to to any > other task or to the kernel ? Accessing through /dev/mem has no impact on the page allocator. Accessing memory through /dev/mem is the same thing as the kernel accessing that memory from within kernel space. You can access allocated pages, unallocated pages, device registers, pretty much anything at all. Writing indiscriminantly through /dev/mem is the same thing as writing indiscriminantly from within a driver. -- Dave Hylands Shuswap, BC, Canada http://www.DaveHylands.com/ -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to [email protected] Please read the FAQ at http://kernelnewbies.org/FAQ
