I don't think anyone EXCEPT root is allowed to open /dev/mem.
--- In "n4rve" <> wrote:
>
> Hi...
>
> I'm just beginning to get my feet wet (OK, barely moist) with this board, so
> please forgive me if this is a PEBCAK (Problem Exists Between Chair And
> Keyboard).
>
> When my 7800 first came up, I was able to use ts7800ctl -n and -F to turn the
> LED on and off. This was fairly exciting, and worked both in root and my
> user account.
>
> However, the next time I tried ts7800ctl in the user account (and every time
> since) I receive this error message on any option:
>
> ts7800ctl: ts7800ctl.c:175: main: Assertion `devmem != -1' failed.
> Aborted
>
> This kind of error is associated with failing to close /dev/mem in a program
> after opening it, and sure enough, when I look at the source:
>
> ftp://ftp.embeddedarm.com/tmp/7800_adc_update/ts7800ctl.c
>
> I see
>
> devmem = open("/dev/mem", O_RDWR|O_SYNC);
>
> just before all the case statements. There is no close. Clearly, however,
> this must be working for other people as it is often cited... so I can't
> imagine that's really the problem.
>
> The puzzle, perhaps negating the question above, is why am I getting the
> abort message on every attempt to use it in user space, even though it still
> works fine in root (assuming I use the explicit path of /usr/local/bin/)?
>
> Cheers,
> Steve
> (who is still puzzled about the lack of sudo)
>
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