Re: Hang in uart_block_til_ready()

[Michael Hanselmann <linux-kernel@hansmi.ch>]

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Hello Russell

On Sun, Apr 02, 2006 at 03:38:27PM +0100, Russell King wrote:
> On Sun, Apr 02, 2006 at 03:51:38PM +0200, Michael Hanselmann wrote:
> > I've discovered a problem where I'm not sure wether it's an error in the
> > kernel or in the hardware.

> It's neither - it's a bug in your test program.  If you want "callout"
> semantics, open the port using O_NONBLOCK mode.

I've now patched screen(1) and it works, but one thing is amazing me.
The other computer I wrote about has the serial console on ttyS0 and
starting screen(1) on the serial console works. Here's the relevant
strace part:

screen-strace:open("/dev/ttyS0", O_RDWR|O_NONBLOCK) = 3
screen-strace.23801:open("/dev/ttyS0", O_RDWR) = 3

This doesn't work on the HP box with the serial console on ttyS2. After
adding O_NONBLOCK, it works. Here's the strace:

screen-strace:open("/dev/ttyS2", O_RDWR|O_NONBLOCK) = 3
screen-strace.31830:open("/dev/ttyS2", O_RDWR|O_NONBLOCK) = 3

Am I going correct that this is a bug in screen(1) and it only works on
the first box by some mysterious reason? Mabye some timing issue?

Thanks,
Michael

-- 
Gentoo Linux developer, http://hansmi.ch/, http://forkbomb.ch/

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