On Sat, 26 Feb 2000, Mike Panetta wrote:
>Should /dev/console always be available even if there is no
>video card or keyboard on a machine? I keep getting these
As a rule, yes. However, intel based systems tend to have serious problem
without a video card in there. Sparcs and most alphas (at least the server
hardware) uses the serial port as the console in the absence of a video
console.
I look at this as a serious flaw in the x86 hardware design, but seeing
as x86 hardware is generally designed for "desktop" applications, I don't
hold it against anyone. (BTW, have you ever tried running NT on a machine
without a video device? It's not pretty unless you have a specialized
version.)
>messages in the logs about init not being able to open(/dev/console)
>when I remove the video card from an embedded box I am working on.
You can compile in serial console support and use "console=ttyS0"
to set the console to the serial port. There were patches as far
back as 1.2 for serial consoles on x86 hardware.
>when I do this strange things start to happen like it cannot properly
>umount /dev/hda5 (not root partition) on shutdown, and mingetty starts
>to respawn to fast. This is related to a previous message I sent to the
>list about a week ago reguarding the ext2 corruption messages without
>a video card in the machine. Since then I have upgraded all the libraries
>to be compilant with the rquirements in Documentation/Changes and the
>corruption has gone away. Now I am stuck with unclean mounts and other
>random occurences...
Bad programs making bad assumptions... from a purist standpoint, one
should check the return values from printf() and things [no one ever
does, tho'. I've seen some programs peg the CPU because of it.]
>What am I to do?
Make sure /dev/console points to a useable device at all times. One could
write a quicky program to check /dev/tty1, /dev/ttyS0, /dev/null, etc. and
replace /dev/console with a symlink. (Of course, one could argue the kernel
console driver should've done that at boot :-))
I quote devices.txt:
5 char Alternate TTY devices
0 = /dev/tty Current TTY device
1 = /dev/console System console
...
That says to me the kernel should always have a valid /dev/console (even if
it has to send it to /dev/null.)
--Ricky
PS: programs not having a stdin, stdout, and stderr is a nasty problem.
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