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RE: Serial getc problem
- From: Gary Thomas <gary at chez-thomas dot org>
- To: George Sosnowski <george at stratalight dot com>
- Cc: eCos Discussion <ecos-discuss at sources dot redhat dot com>
- Date: 08 Jul 2002 10:43:10 -0600
- Subject: RE: [ECOS] Serial getc problem
- References: <F626113795D3EB4482E5ACFBD9346512138308@mailhost.stratalight.com>
On Mon, 2002-07-08 at 10:35, George Sosnowski wrote:
> I have come across a similar situation using the 860T. My platform has
> one serial port (SMC1 used as diag and console port) and currently I
> inherit the serial channel from redboot. Is it still possible to have a
> 'proper' /dev/tty0 that uses the inherited serial channel (diag/console)
> from redboot? Or does the ecos ram image have to install its own
> /dev/ser0 for console and diag channels since these are the same device?
>
If you want non-blocking (i.e. interrupt driven) I/O, you need to use
/dev/ser0. I/O through the default console /dev/ttydiag will always be
blocking (non interrupt driven). For the most part, these can usually
co-exist, with the caveats that output from the non-interrupting device
could intermingle with that from the interrupting device and that if you
use GDB features then only blocking I/O will be used while GDB is in
control.
> Thanks,
> George
>
> -----Original Message-----
> From: Robert Cragie [mailto:rcc@jennic.com]
> Sent: Thursday, July 04, 2002 10:26 AM
> To: Daniel Lidsten; ecos-discuss@sources.redhat.com
> Subject: RE: [ECOS] Serial getc problem
>
> You need to use a 'proper' serial driver (/dev/tty0 or /dev/tty1), not
> /dev/ttydiag. These allow blocking reads which will allow other threads
> to
> run; as you have seen, /dev/ttydiag does a busy wait on a character
> which
> will stop other threads from running. You can configure eCos so that
> stdio
> uses /dev/tty0 or /dev/tty1.
>
> Regards,
>
> Robert Cragie, Design Engineer
>
> Direct: +44 (0) 114 281 4512
> ________________________________________________________
> Jennic Ltd, Furnival Street, Sheffield, S1 4QT, UK
> www.jennic.com Tel: +44 (0) 114 281 2655
>
>
> > -----Original Message-----
> > From: ecos-discuss-owner@sources.redhat.com
> > [mailto:ecos-discuss-owner@sources.redhat.com]On Behalf Of Daniel
> > Lidsten
> > Sent: 04 July 2002 17:19
> > To: ecos-discuss@sources.redhat.com
> > Subject: [ECOS] Serial getc problem
> >
> >
> > Hi,
> >
> > I am running a MPC850 with a few different threads in the application.
> > The network stack is also enabled and up and running. However, when a
> > thread calls the HAL_DIAG_READ_CHAR to wait for input from the user
> then
> > my net stack stops working. I cant reach it with a ping from my local
> > host.
> >
> > My first thought was that the application was running with a higher
> > priority (lower value) then the net stack but that was not the case.
> The
> > application runs at prio 8 and net at 6 and 7 (background).
> >
> > I have seen in the serial driver that when reading a char from the
> port
> > then the following is done:
> >
> > while ( !getc_non_block(..) )
> >
> > Can the problem be that this code is running in some form of "kernel
> > state" i.e. in a very high prio state since the driver lies within
> eCos?
> >
> > Regards, Daniel
> >
> > --
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> >
> >
>
>
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