* serial console problems with 2.4.4
@ 2001-05-02 9:54 Reto Baettig
2001-05-02 11:15 ` Fabrice Gautier
0 siblings, 1 reply; 6+ messages in thread
From: Reto Baettig @ 2001-05-02 9:54 UTC (permalink / raw)
To: Linux Alpha mailing list, Linux Kernel Mailinglist
Hi
I just installed 2.4.4 on our alpha SMP boxes (ES40) and now I have
problems with the serial console:
sulogin does not accept input from the serial line
mingetty does not accept input from the serial line
agetty works fine
Everything works fine for the 2.4.2 kernel. I took the .config file from
the 2.4.2 kernel to compile the 2.4.4 kernel.
Any ideas?
Reto
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: serial console problems with 2.4.4
2001-05-02 9:54 serial console problems with 2.4.4 Reto Baettig
@ 2001-05-02 11:15 ` Fabrice Gautier
2001-05-02 16:37 ` Eric W. Biederman
0 siblings, 1 reply; 6+ messages in thread
From: Fabrice Gautier @ 2001-05-02 11:15 UTC (permalink / raw)
To: Reto Baettig; +Cc: Linux Alpha mailing list, Linux Kernel Mailinglist
On Wed, 02 May 2001 11:54:11 +0200
Reto Baettig <baettig@scs.ch> wrote:
> Hi
>
> I just installed 2.4.4 on our alpha SMP boxes (ES40) and now I have
> problems with the serial console:
I get same kind of problem when upgrading from 2.4.2 to 2.4.3 and using
busybox as init/getty
The problem was a bug in busybox. The console initialisation code was
not correct.
>
> sulogin does not accept input from the serial line
> mingetty does not accept input from the serial line
> agetty works fine
So this this probably a sulogin/mingetty problem. They should set the
CREAD flag in your tty c_cflag.
the patch for busybox repalced the line
tty.c_cflag |= HUPCL|CLOCAL
by
tty.c_cflag |= CREAD|HUPCL|CLOCAL
Hope this help.
--
Fabrice Gautier <gautier@email.enstfr>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: serial console problems with 2.4.4
2001-05-02 11:15 ` Fabrice Gautier
@ 2001-05-02 16:37 ` Eric W. Biederman
2001-05-02 18:52 ` Fabrice Gautier
0 siblings, 1 reply; 6+ messages in thread
From: Eric W. Biederman @ 2001-05-02 16:37 UTC (permalink / raw)
To: Fabrice Gautier
Cc: Reto Baettig, Linux Alpha mailing list, Linux Kernel Mailinglist
Fabrice Gautier <gautier@email.enst.fr> writes:
> On Wed, 02 May 2001 11:54:11 +0200
> Reto Baettig <baettig@scs.ch> wrote:
>
> > Hi
> >
> > I just installed 2.4.4 on our alpha SMP boxes (ES40) and now I have
> > problems with the serial console:
>
> I get same kind of problem when upgrading from 2.4.2 to 2.4.3 and using
> busybox as init/getty
>
> The problem was a bug in busybox. The console initialisation code was
> not correct.
> >
> > sulogin does not accept input from the serial line
> > mingetty does not accept input from the serial line
> > agetty works fine
>
> So this this probably a sulogin/mingetty problem. They should set the
> CREAD flag in your tty c_cflag.
>
> the patch for busybox repalced the line
> tty.c_cflag |= HUPCL|CLOCAL
> by
> tty.c_cflag |= CREAD|HUPCL|CLOCAL
>
> Hope this help.
This part is correct.
However the kernel sets CREAD by default.
sysvinit (and possibly other inits) clears CREAD.
I wish I knew where the breakage actually occured.
And then sulogin/mingetty need to reenable it.
It's not too big of a deal except the serial code doesn't accept SAK's
when CREAD is clear.
Eric
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: serial console problems with 2.4.4
2001-05-02 16:37 ` Eric W. Biederman
@ 2001-05-02 18:52 ` Fabrice Gautier
2001-05-03 8:15 ` Eric W. Biederman
0 siblings, 1 reply; 6+ messages in thread
From: Fabrice Gautier @ 2001-05-02 18:52 UTC (permalink / raw)
To: Eric W. Biederman; +Cc: Linux Kernel Mailinglist
On 02 May 2001 10:37:21 -0600
ebiederm@xmission.com (Eric W. Biederman) wrote:
> Fabrice Gautier <gautier@email.enst.fr> writes:
> > So this this probably a sulogin/mingetty problem. They should set the
> > CREAD flag in your tty c_cflag.
> >
> > the patch for busybox repalced the line
> > tty.c_cflag |= HUPCL|CLOCAL
> > by
> > tty.c_cflag |= CREAD|HUPCL|CLOCAL
> >
> > Hope this help.
>
> This part is correct.
>
> However the kernel sets CREAD by default.
Are your sure? Wasn't this the behaviour for 2.4.2 but changed in 2.4.3
> sysvinit (and possibly other inits) clears CREAD.
In my case I was using busybox as init. So there is no sysinit or any other
init called before this line.
> I wish I knew where the breakage actually occured.
Just look at this diff on serial.c between 2.4.2 and 2.4.3:
--- serial.c Sat Apr 21 17:22:53 2001
+++ ../../../linux-2.4.2/drivers/char/serial.c Sat Feb 17 01:02:36 2001
@@ -1764,8 +1765,8 @@
/*
* !!! ignore all characters if CREAD is not set
*/
-// if ((cflag & CREAD) == 0)
-// info->ignore_status_mask |= UART_LSR_DR;
+ if ((cflag & CREAD) == 0)
+ info->ignore_status_mask |= UART_LSR_DR;
save_flags(flags); cli();
if (uart_config[info->state->type].flags & UART_STARTECH) {
serial_outp(info, UART_LCR, 0xBF);
--
Fabrice Gautier <gautier@email.enstfr>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: serial console problems with 2.4.4
2001-05-02 18:52 ` Fabrice Gautier
@ 2001-05-03 8:15 ` Eric W. Biederman
2001-05-03 12:30 ` Fabrice Gautier
0 siblings, 1 reply; 6+ messages in thread
From: Eric W. Biederman @ 2001-05-03 8:15 UTC (permalink / raw)
To: Fabrice Gautier; +Cc: Linux Kernel Mailinglist
Fabrice Gautier <gautier@email.enst.fr> writes:
> On 02 May 2001 10:37:21 -0600
> ebiederm@xmission.com (Eric W. Biederman) wrote:
>
> > Fabrice Gautier <gautier@email.enst.fr> writes:
> > > So this this probably a sulogin/mingetty problem. They should set the
> > > CREAD flag in your tty c_cflag.
> > >
> > > the patch for busybox repalced the line
> > > tty.c_cflag |= HUPCL|CLOCAL
> > > by
> > > tty.c_cflag |= CREAD|HUPCL|CLOCAL
> > >
> > > Hope this help.
> >
> > This part is correct.
> >
> > However the kernel sets CREAD by default.
>
> Are your sure? Wasn't this the behaviour for 2.4.2 but changed in 2.4.3
init=/bin/bash works fine over a serial console in 2.4.4. So I am
certain.
I get the impression that something in 2.4.3 fixed CREAD handling, and we
started noticing the buggy user space.
> > sysvinit (and possibly other inits) clears CREAD.
>
> In my case I was using busybox as init. So there is no sysinit or any other
> init called before this line.
The busy box init is also clearing CREAD (as of 0.51 anyway).
> > I wish I knew where the breakage actually occured.
>
> Just look at this diff on serial.c between 2.4.2 and 2.4.3:
If it was a real diff between 2.4.2 and 2.4.3 I would agree, however it looks
like your attempt to fix 2.4.3.
Eric
> --- serial.c Sat Apr 21 17:22:53 2001
> +++ ../../../linux-2.4.2/drivers/char/serial.c Sat Feb 17 01:02:36 2001
> @@ -1764,8 +1765,8 @@
> /*
> * !!! ignore all characters if CREAD is not set
> */
> -// if ((cflag & CREAD) == 0)
> -// info->ignore_status_mask |= UART_LSR_DR;
> + if ((cflag & CREAD) == 0)
> + info->ignore_status_mask |= UART_LSR_DR;
> save_flags(flags); cli();
> if (uart_config[info->state->type].flags & UART_STARTECH) {
> serial_outp(info, UART_LCR, 0xBF);
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: serial console problems with 2.4.4
2001-05-03 8:15 ` Eric W. Biederman
@ 2001-05-03 12:30 ` Fabrice Gautier
0 siblings, 0 replies; 6+ messages in thread
From: Fabrice Gautier @ 2001-05-03 12:30 UTC (permalink / raw)
To: Eric W. Biederman; +Cc: Linux Kernel Mailinglist
On 03 May 2001 02:15:03 -0600
ebiederm@xmission.com (Eric W. Biederman) wrote:
>
> I get the impression that something in 2.4.3 fixed CREAD handling, and we
> started noticing the buggy user space.
That's my impression too...
> > > I wish I knew where the breakage actually occured.
> >
> > Just look at this diff on serial.c between 2.4.2 and 2.4.3:
>
> If it was a real diff between 2.4.2 and 2.4.3 I would agree, however it looks
> like your attempt to fix 2.4.3.
Err... Yes sorry, in fact this was a workaround proposed by Kanoj, the
maintener of serial.c (I think)...
Regards.
--
Fabrice Gautier <gautier@email.enstfr>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2001-05-03 12:31 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2001-05-02 9:54 serial console problems with 2.4.4 Reto Baettig
2001-05-02 11:15 ` Fabrice Gautier
2001-05-02 16:37 ` Eric W. Biederman
2001-05-02 18:52 ` Fabrice Gautier
2001-05-03 8:15 ` Eric W. Biederman
2001-05-03 12:30 ` Fabrice Gautier
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