Messages in this thread | | | Date | Wed, 11 Aug 2004 14:51:13 +0200 | From | Erik Mouw <> | Subject | Re: Fork and Exec a process within the kernel |
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On Wed, Aug 11, 2004 at 07:55:52AM -0400, Richard B. Johnson wrote: > RedHat is NOT Linux. The MAJOR-MINOR 5.1 used in RedHat for the > console has a very serious problem for anybody doing development > work. If there are any kernel messages, they go to __all__ open > terminals. This means that the only "quiet" terminals that may be > available to kill off a runaway process are available iff you can > log in over the network.
If you don't want console messages, you just disable console at all, or you use a serial console (using the "console=" on the kernel command line), or you adjust the kernel console log level. Please have a look at the "dmesg" manual page, especially the "-n" parameter. In emergency situations, Alt-Sysrq-[0-8] will allow you to do the same (on VGA consoles for PCs, that is. for serial consoles use Break-[0-8]).
> Most everybody I know, who does serious development work, and > certainly those who want to control where the %*)&$#!@ kernel > messages go, will make sure they go to the "ALT-F1" as I have > shown.
Not all the world is a PC, there is a lot of linux beyond x86. Looks to me like you haven't done development on embedded systems that don't have any VGA terminal at all.
Getting kernel messages on a certain pseudo tty is just a matter of supplying the correct "console=" paramater to the kernel. For example: "console=tty1" will get your console output on pseudo tty 1. Alternatively, you can configure syslog to write all kernel messages to a pseudo tty.
> The original query was about how to make kernel messages > go to where, i.e., what VT do they come from. I have shown > how you can control where they go.
Here is the original question:
Thanks for the pointer! My user mode program is running. Any idea how to control which console it shows up on?
No reference on how to get kernel messages somewhere.
> Now, if you look at the kernel source, you will note that > just prior to attempting to exec /sbin/init, /dev/console > is opened. This means that you can properly use whatever > you want if you continue to use a sym-link.
That was true for linux < 2.1.71, which was released almost 7 years ago. Things have changed. Newer kernels use the "console=" kernel command line to select the console. With multiple the "console=" parameter, you can even have mutiple consoles.
Erik
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