| 2008-04-30 18:09:20 |
Dustin Kirkland |
description |
Binary package hint: grub
A curious error with grub's serial console configuration.
Currently, we're only seeing this on a single machine, an HP DL145.
An installation is performed with console=ttyS0,9600n8 on the kernel command line. Install progresses smoothly, with everything visible in the console. This indicates that the hardware is okay, considering the Linux kernel can output and gather input from the serial console.
The installter writes /boot/grub/menu.lst with the first two lines being:
serial --unit=0 --speed=9600 --word=8 --parity=no --stop=1
terminal serial
Additionally, console=ttyS0,9600n8 is appended on each of the kernel boot lines in that same file.
It seems that the kernel console redirection to serial works, however the grub serial console does not. In fact, it hangs grub, just after loading stage 1.5.
The next step would be to build and install a special debug grub package on that machine which would verbosely log its doings on load. This would require an IS person in the lab to watch the physical console, as any remote developer is entirely blind at any time when reproducing this problem.
*** WORK AROUND ***
The problem can be worked around by commenting out in menu.lst:
# serial --unit=0 --speed=9600 --word=8 --parity=no --stop=1
# terminal serial
This will remove the ability to see the Grub menu, however, as soon as the kernel is booted with console=ttyS0,9600n8, the serial console will be associated again.
Note that the only two values allowed for stop are 1 and 2. See:
http://tldp.org/HOWTO/Remote-Serial-Console-HOWTO/preparation-setspeed.html
Setting --stop=0 in menu.lst "works", however for undesired reasons. Basically, 0 is an invalid value, and as such, Grub just skips that line. In which case, commenting the line out actually makes more sense.
:-Dustin |
Binary package hint: grub
A curious error with grub's serial console configuration.
Initially, we only saw this on a single machine, an HP DL145.
We have reports of this happening on other hardware, as well as other Linux distributions.
An installation is performed with console=ttyS0,9600n8 on the kernel command line. Install progresses smoothly, with everything visible in the console. This indicates that the hardware is okay, considering the Linux kernel can output and gather input from the serial console.
The installter writes /boot/grub/menu.lst with the first two lines being:
serial --unit=0 --speed=9600 --word=8 --parity=no --stop=1
terminal serial
Additionally, console=ttyS0,9600n8 is appended on each of the kernel boot lines in that same file.
It seems that the kernel console redirection to serial works, however the grub serial console does not. In fact, it hangs grub, just after loading stage 1.5.
The next step would be to build and install a special debug grub package on that machine which would verbosely log its doings on load. This would require an IS person in the lab to watch the physical console, as any remote developer is entirely blind at any time when reproducing this problem.
*** WORK AROUND ***
The problem can be worked around by commenting out in menu.lst:
# serial --unit=0 --speed=9600 --word=8 --parity=no --stop=1
# terminal serial
This will remove the ability to see the Grub menu, however, as soon as the kernel is booted with console=ttyS0,9600n8, the serial console will be associated again.
Note that the only two values allowed for stop are 1 and 2. See:
http://tldp.org/HOWTO/Remote-Serial-Console-HOWTO/preparation-setspeed.html
Setting --stop=0 in menu.lst "works", however for undesired reasons. Basically, 0 is an invalid value, and as such, Grub just skips that line. In which case, commenting the line out actually makes more sense.
:-Dustin |
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