It is allway good to know how kernel variables can be set at boot

This is from forums.gentoo.org

Posted: Wed Sep 16, 2009 9:57 am Post subject: Cinelerra /proc/sys/kernel/shmmax error
Starting Cinelerra video editing app results in the following error:
Code:
Void MWindow::init_shm(): WARNING: /proc/sys/kernel shmmax is 0x2000000, which is too low.
Before running Cinerella do the following as root:
echo "0x7ffffff" > /proc/sys/kernel/shmmax


What's happen and how can i solve it?
Is it secure overwrite shmmax?

Posted: Wed Sep 16, 2009 10:52 am Post subject:
shmmax is just the maximum sized memory segment a process can request, an increase shouldn't really be a security issue, and the increase they're asking for is only 4 times the default, which isn't that much.

You can just add "kernel.shmmax 134217728" to /etc/sysctl.conf to have it set to 0x8000000 upon each boot.
Alternatively you could just run the echo command as suggested, and then run `echo 33554432 > /proc/sys/kernel/shmmax` to reset it to the default when finished with cinerella, if you're really concerned about it.

So, I'll be looking at /etc/sysctl.conf sometime soon, and maybe read more about it, starting with the man page.