Re: syscall __NR_mmap2

["Richard B. Johnson" <root@chaos.analogic.com>]

On Mon, 7 Jul 2003, Ulrich Drepper wrote:

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> Richard B. Johnson wrote:
>
> > write(1, "Addr = 000b8000\n", 16)       = 16
> > open("/dev/mem", O_RDWR)                = 3
> > mmap2(0xb8000, 8192, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FIXED, 3, 0xb8000) = 0xb8000
>
> mmap64() (and if you compile glibc with an adequate minimal kernel
> requirement mmap as well) is implemented using mmap2.  It works nicely.
>  Admittedly, I haven't used the stock 2.4 kernel.  And I also haven't
> used /dev/mem.  But at least for the first part I would expect to see
> problem reports since the code is used and glibc wouldn't work.
>
> In your code, assuming this is x86, do you really want to read the
> memory starting at address 0xb8000000?  This is what your code does.  I
> don't know enough about the kernel memory layout to say whether
> something is supposed to be there or not.
>

Yes. Thanks. There is no known documentation that states that
the address to the function is in PAGES. Certainly, this will
work once I use pages instead of bytes.

Cheers,
Dick Johnson
Penguin : Linux version 2.4.20 on an i686 machine (797.90 BogoMips).
Why is the government concerned about the lunatic fringe? Think about it.