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Re: Troubles when processes try to access to a char device

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Il 27/02/2012 16:08, gwowen ha scritto:
> presumably
>    int fd;
>
> That'll probably be your issue. By default, file descriptors only have
> meaning on a per-process basis.
> So if two separate processes use the same integer descriptor, they
> won't be reading from the same stream - and all the shared memory
> segment shares is the integer.
>
> There are mechanisms for sharing file-descriptors, fork()/exec() or
> sendmsg()/recvmsg() are the most common, but they probably won't work
> they way you want.
>
> The best bet may be for each process to open their own file descriptor
> for the device, and for shared memory / IPC to coordinate the reads /
> writes through some sort of mutual exclusion, but it all depends on
> the access pattern you need.

Thanks :)
I've understood the problem: file descriptor isn't just an int!
Now I'm trying to find out the best solution.

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Thread

Troubles when processes try to access to a char device Willy <gruppi@willygroup.org> - 2012-02-27 08:58 +0100
  Re: Troubles when processes try to access to a char device gwowen <gwowen@gmail.com> - 2012-02-27 05:19 -0800
    Re: Troubles when processes try to access to a char device Willy <gruppi@willygroup.org> - 2012-02-27 14:41 +0100
      Re: Troubles when processes try to access to a char device gwowen <gwowen@gmail.com> - 2012-02-27 07:08 -0800
        Re: Troubles when processes try to access to a char device Willy <gruppi@willygroup.org> - 2012-02-27 16:42 +0100
          Re: Troubles when processes try to access to a char device gwowen <gwowen@gmail.com> - 2012-02-27 09:29 -0800
          Re: Troubles when processes try to access to a char device Dan Oxender <d?n.oxe????@gmail.com> - 2012-02-28 09:06 -0700
  Re: Troubles when processes try to access to a char device Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2012-02-27 14:38 +0100

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