System information
208 System Analysis and Tuning Guide
6 Remount the root file system in read-only mode:
mount -o remount,ro /
7 Initiate the reboot of the kernel that you loaded in Step 4 (page207) with kex-
ec -e
It is important to unmount the previously mounted disk volumes in read-write mode.
The reboot system call acts immediately upon calling. Hard drive volumes mounted
in read-write mode neither synchronize nor unmount automatically. The new kernel
may find them “dirty”. Read-only disk volumes and virtual file systems do not need
to be unmounted. Refer to /etc/mtab to determine which file systems you need to
unmount.
The new kernel previously loaded to the address space of the older kernel rewrites it
and takes control immediately. It displays the usual start-up messages. When the new
kernel boots, it skips all hardware and firmware checks. Make sure no warning mes-
sages appear. All the file systems are supposed to be clean if they had been unmount-
ed.
18.5 How to Configure kexec for
Routine Reboots
kexec is often used for frequent reboots. For example, if it takes a long time to run
through the hardware detection routines or if the start-up is not reliable.
NOTE: Rebooting with kexec
In previous versions of SUSE® Linux Enterprise Server, you had to manually
edit the configuration file /etc/sysconfig/shutdown and the init script /
etc/init.d/halt to use kexec to reboot the system. You no longer need
to edit any system files, since version 11 is already configured for kexec re-
boots.
Note that firmware as well as the boot loader are not used when the system reboots
with kexec. Any changes you make to the boot loader configuration will be ignored
until the computer performs a hard reboot.