After installation machine hangs during first boot

Have you installed Red Hat Enterprise Linux only to have it hang on its first boot? Sometimes an Advanced Power Management (APM) bug causes this. APM communicates with the system BIOS; if the system does not support it, it can hang. Check whether the system hangs before all services have loaded. If so, this may be the cause.

The solution is to set apm=off.

For a temporary fix, edit the GRUB entry directly as follows:

When the GRUB boot screen (the countdown screen) appears, press “e”.
Move to the line beginning with kernel and press ‘e’ again.
Add apm=off as shown below.
kernel /vmlinuz-2.4.21-20.EL ro root=LABEL=/ apm=off
Press ‘Enter’.
Press ‘b’ to boot the system.

If the machine boots without hanging, this was probably the cause. Make the following additional change to avoid entering these settings at every boot.

Edit /etc/grub.conf and add apm=off to the kernel line, as shown:


default=1
timeout=7
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title Red Hat Enterprise Linux AS (2.4.21-20.EL)
root (hd0,0)
kernel /vmlinuz-2.4.21-20.EL ro root=LABEL=/ <strong>apm=off</strong>
initrd /initrd-2.4.21-20.EL.img
title Red Hat Enterprise Linux AS (2.4.21-20.ELsmp)
root (hd0,0)
kernel /vmlinuz-2.4.21-20.ELsmp ro root=LABEL=/ <strong>apm=off</strong>
initrd /initrd-2.4.21-20.ELsmp.img

After editing the file, the change is complete and the problem should not recur on the next boot.