open("/dev/mem", O_RDWR) = 4
mmap(0, 65536, PROT_READ|PROT_WRITE, MAP_SHARED, 4, 0xa0000) = 0x400d7000
close(4) = 0
The return value is a nice high value which doesn't confuse any 'C'
runtime libraries.
If I attempt to mmap 0xb8000, the screen regen buffer, it succeeds
(because it doesn't return a -1), but it returns 0. The result, cast
to a pointer does 'work' for reading and writing to the screen buffer.
However, the resulting NULL pointer is not a real good thing to use
in user-space since bad code won't seg-fault.
So, what is the correct way to mmap a physical address into user space?
Is there some offset I should be using? In the intended application,
I am not really going to read/write to the screen regen buffer, but
it's an interesting target to play with.
Cheers,
Dick Johnson
***** FILE SYSTEM WAS MODIFIED *****
Penguin : Linux version 2.2.6 on an i686 machine (400.59 BogoMips).
Warning : It's hard to remain at the trailing edge of technology.
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