Bootloader Updates | Building Tablet PC Applications (Pro-Developer)

While GRUB is the default bootloader for Red Hat Linux, LILO is still in fairly common use. When you recompile a kernel, you should set up your bootloader to boot from either kernel, as though they were two distinct operating systems. Although bootloader updates aren t a part of the make process, the steps you need to update either bootloader are fairly straightforward.

Updating GRUB

Assuming GRUB is your bootloader, open /etc/grub.conf in the text editor of your choice. If Red Hat Linux is the only operating system on your computer, the key commands are as follows :

 default=0 title Red Hat Linux (2.4.20-8)   root (hd0,1)   kernel /vmlinuz-2.4.20-8 ro root=LABEL=/   initrd /initrd-2.4.20-8.img

Now take the kernel that you just recompiled. The main compressed kernel file is vmlinuz-2.4 .20-sugaree; the corresponding Initial RAM file is initrd-2.4.20sugaree.img . Since you ve installed these files in the same /boot directory, none of the other parameters will change. You can add a second stanza with the newly compiled kernel:

 default=0 title Red Hat Linux (2.4.20-8)   root (hd0,1)   kernel /vmlinuz-2.4.20-8 ro root=LABEL=/   initrd /initrd-2.4.20-8.img  title Red Hat Linux (2.4.20sugaree)   root (hd0,1)   kernel /vmlinuz-2.4.20sugaree ro root=LABEL=/   initrd /initrd-2.4.20sugaree.img

Remember, nothing more is required. When you reboot your computer, you ll see both titles in the GRUB menu, as shown in Figure 12.45. Since default=0 , the old kernel in the first stanza is still the default. We described a similar version of grub.conf in Figure 12.2 . For a detailed analysis of GRUB, see Chapter 11 .

Figure 12.45: Revised GRUB

Updating LILO

If you use LILO as your bootloader, open /etc/lilo.conf in the text editor of your choice. If Red Hat Linux is the only operating system on your computer, the key commands are as follows:

 default=linux image=/boot/vmlinuz-2.4.20-8     label=linux     initrd=/boot/initrd-2.4.20-8.img     read-only     append="root=LABEL=/"

Now take the kernel that you just recompiled. The main compressed kernel file is vmlinuz-2.4.20sugaree; the corresponding Initial RAM file is initrd-2.4.20sugaree.img . Since you ve installed these files in the same /boot directory, none of the other parameters will change. You can add a second stanza with the newly compiled kernel:

 default=linux image=/boot/vmlinuz-2.4.20-8     label=linux     initrd=/boot/initrd-2.4.20-8.img     read-only     append="root=LABEL=/"  image=/boot/vmlinuz-2.4.20sugaree   label=linux-sugaree   initrd=/boot/initrd-2.4.20sugaree.img   read-only   append="root=LABEL=/"

Save your changes. With LILO, you need to run the lilo command to write the changes to the MBR of your hard disk. Since the default setting is linux , LILO will still automatically boot your old kernel unless you specifically select the new one in the LILO boot menu.