On Wed, Sep 28, 2016 at 2:49 AM, Paddie O'Brien <[email protected]> wrote:
> Hi, > > I have a system call that maps virtual to physical addresses. I have > disabled CONFIG_STRICT_DEVMEM and am reading from /dev/mem to verify > that the contents of the syscall-returned physical address match the > contents of the virtual address. It works fine up to a point. Reading > beyond byte 935321597 in /dev/mem throws a "bad address" error. Not > sure it's relevant but I'm running on virtual box and specifying 1GB > of RAM. Tried with 2GB of RAM and hit the same problem. > > Any idea why I can't read beyond the above point? > > Thanks. > > Hi paddie Is it 32 bit system? If yes, it seems you are about to exceed boundary of kernel linear addres range, which is 0-896 MiB. The upper 896-1024 MiB (1 GiB) is reserved for dynamic mapping CMIIW people. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com
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