On Feb 26, 4:58 am, email7373...@kinglibrary.net wrote:
> I want to move to linux from DOS / Win98, and the piece of hardware
> communicates this way (see snippet below).
>
> This snippet works just fine in DOS / Win98, but in linux it fails
> with a segmentation fault. Any idea how to make it work?
>
> #include
>
> typedef unsigned long DWORD;
> typedef unsigned char BYTE;
> typedef unsigned short WORD;
>
> volatile WORD *memory_word_pointer;
>
> DWORD pmem_address = 0xD4000;
>
> void *return_address (DWORD address)
> {
> return (BYTE *) address;
>
> }
>
> int main()
> {
> memory_word_pointer = (WORD *)return_address (pmem_address);
>
> *memory_word_pointer = 0x1000;
> return 1;
>
> }

Probably the best solution is to create a proper driver, but you might
be okay just using '/dev/mem'. Type 'man 4 mem'.

DS

email7373388@kinglibrary.net writes:

> I want to move to linux from DOS / Win98, and the piece of hardware
> communicates this way (see snippet below).
>
> This snippet works just fine in DOS / Win98, but in linux it fails
> with a segmentation fault. Any idea how to make it work?

You can't.

Based on the variable names in the code, you seem to be assuming that
you can get direct access to physical memory addresses. A program
under Linux only sees virtual addresses.

I assume there is something interesting at that physical address. If
that's a device of some sort, there is almost certainly a device
driver to control it; learn the driver. Alternatively, man mem.

Note that the fact code like that works under DOS and 16-bit Windows
is the reason a single application with a wild pointer can crash the
system.

There are some hardware components involved but they are quite old and
there aren't any drivers for linux.

Creating an honest-to-goodness driver may be more that I need for this
project, I'll research using mem. Thank you much for the replies!!