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List:       uclinux-dev
Subject:    [uClinux-dev] Re: uClinux 2.4.x Kernel: Hardcoded Console Speed
From:       Greg Ungerer <gerg () snapgear ! com>
Date:       2007-06-28 12:23:15
Message-ID: 4683A833.6050000 () snapgear ! com
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Hi Paul,

Paul Romero wrote:
> The speed of the console--/dev/ttyS0, is hardcoded to 19200
> baud in the 2.4.x kernel.  This means that fcntl() and similar
> calls can not be used to change the speed.

No, that is not correct.

The _default_ speed is hard coded. And that is only used
on system startup - as the initial setting.

Once the system/driver is operational the usual serial port
mechanisms (via ioctl's, etc) can be used. Note that
you cannot set serial port speed with fcntl().

As Erwin pointed out you can ofcourse change this default
on the boot command line too.

Regards
Greg


> You can quickly grasp the problem if you search for
> CONSOLE_BAUD_RATE in the file
> linux-2.4.x/drivers/char/mcfserial.c. I believe that
> is the only file that needs to be modified to make
> the speed of ttyS0 configurable like other ttys ?
> Is that correct ?
> 
> More importantly, has someone already made the ttyS0
> speed configurable, and if so, where can one obtain the
> relevant code ?
> 
> Note: I am using UC Linux release 2.4.27 with the 2.4.x kernel
> on an M5249C3.
> 
> Best Regards,
> 
> Paul R.
> 
> 
> --
> Paul Romero
> 
> RCOM Communications Software
> 
> Phone/Fax: (510)339-2628
> E-Mail: paulr@rcom-software.com
> 
> 
> 


-- 
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Greg Ungerer  --  Chief Software Dude       EMAIL:     gerg@snapgear.com
SnapGear -- a Secure Computing Company      PHONE:       +61 7 3435 2888
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