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Subject: [Bug 1001466] /dev/null serial driver
Date: Thu, 16 Feb 2012 12:20:00 -0000	[thread overview]
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--- Comment #5 from Sergei Gavrikov <> 2012-02-16 12:20:05 GMT ---
(In reply to comment #4)


> Well the name '/dev/null' is known for decades and for any *nix
> developer this name tells what it does, as posix/opengroup use this
> name.

But it is not terminal/teletype/console/serial, etc. From your source
(Open Group)

    An infinite data source and data sink. Data written to /dev/null
    shall be discarded. Reads from /dev/null shall always return
    end-of-file (EOF).

(EOF) - END OF *FILE*. As I said /dev/null is a special FILE. But,
/dev/null is not TTY device (not terminal):

Check in Python

  >>> import os
  >>>"/dev/null", os.O_RDWR)
  >>> os.isatty(fd)

Check in C

  % cc -xc - <<EOF
  > main(){printf("/dev/null is %s
  % ./a.out
  /dev/null is not tty


> AFAIK there is no specific requirements regarding the implementation,
> only the name and the result it must provide. Using the serial
> abstraction seemed fine to me since most often /dev/null is used to
> sink data coming from a byte stream. I suppose that serial devices are
> embedded in all targets, at least for diag_printf(), that why I placed
> it here so there is no need to bring other components.

If your concern is diagnostic output only (diag_printf()), you ain't
gonna need it. I mean /dev/null. The eCos diagnostic routines do not use
devfs. Look


HAL_DIAG_WRITE_CHAR() macro is defined in hal_diag.h as

#define HAL_DIAG_WRITE_CHAR(_c_) hal_if_diag_write_char(_c_)



Using CYGACC_CALL_IF_* macros you can (re-)assign diagnostic channel
anywhere, for example, to some auxiliary COMM channel (black-hole).
Excellent example how to to deal with eCos COMM channels is RedBoot


Look around mon_write_char() there. So, (IMHO) in the simplest case you
would just use diag_init_putc() to solve your issue.

More on eCos VV & COMMS channels

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  parent reply	other threads:[~2012-02-16 12:20 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-27 17:39 [Bug 1001466] New: " bugzilla-daemon
2012-01-27 19:14 ` [Bug 1001466] " bugzilla-daemon
2012-02-15 13:47 ` bugzilla-daemon
2012-02-15 13:48 ` bugzilla-daemon
2012-02-15 20:46 ` bugzilla-daemon
2012-02-16  9:55 ` bugzilla-daemon
2012-02-16 14:01   ` Grant Edwards
2012-02-16 12:20 ` bugzilla-daemon [this message]
2012-02-16 14:21 ` bugzilla-daemon
2012-02-16 15:06 ` bugzilla-daemon
2012-02-16 15:39 ` bugzilla-daemon
2012-02-16 15:58 ` bugzilla-daemon
2012-02-16 16:26 ` bugzilla-daemon
2012-02-16 16:37 ` bugzilla-daemon
2012-02-16 16:49 ` bugzilla-daemon
2012-02-16 17:21 ` bugzilla-daemon
2012-02-17  6:17 ` bugzilla-daemon
2012-02-18 19:38 ` bugzilla-daemon

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