Messages in this thread |  | | Subject | Re: serial console problems with 2.4.4 | From | (Eric W. Biederman) | Date | 03 May 2001 02:15:03 -0600 |
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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); >
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