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5.2. Configure Linux kernel using GRUB
Find each title entry in the GRUB configuration file. It will be followed by a kernel line. For example
title Red Hat Linux (2.4.9-21) root (hd0,0) kernel /vmlinuz-2.4.9-21 ro root=/dev/hda6 initrd /initrd-2.4.9-21.img |
Modify each of the kernel lines to append the parameters that inform the kernel to use a serial console.
Figure 5-5. Recommened kernel parameters, GRUB configuration
title Red Hat Linux (2.4.9-21) root (hd0,0) kernel /vmlinuz-2.4.9-21 ro root=/dev/hda6 console=tty0 console=ttyS0,9600n81 initrd /initrd-2.4.9-21.img |
As a complete example, Example 5-3 is a typical GRUB configuration from Red Hat Linux 7.2.
Example 5-3. Complete GRUB configuration, as installed by vendor
default=0 timeout=10 splashimage=(hd0,0)/grub/splash.xpm.gz password --md5 $1$wwmIq64O$2vofKBDL9vZKeJyaKwIeT. title Red Hat Linux (2.4.9-21) root (hd0,0) kernel /vmlinuz-2.4.9-21 ro root=/dev/hda6 initrd /initrd-2.4.9-21.img |
The modified configuration file is shown in Example 5-4.
Example 5-4. Complete GRUB configuration, modified for serial console
default=0 timeout=10 password --md5 $1$wwmIq64O$2vofKBDL9vZKeJyaKwIeT. serial --unit=0 --speed=9600 -word=8 --parity=no --stop=1 terminal --timeout=10 serial console title Red Hat Linux (2.4.9-21) root (hd0,0) kernel /vmlinuz-2.4.9-21 ro root=/dev/hda6 console=tty0 console=ttyS0,9600n81 initrd /initrd-2.4.9-21.img title Red Hat Linux (2.4.9-21) single user mode lock root (hd0,0) kernel /vmlinuz-2.4.9-21 ro root=/dev/hda6 console=tty0 console=ttyS0,9600n81 s initrd /initrd-2.4.9-21.img |