On the IA64 platform, the boot loader is called elilo. First install the software on the system:
emerge --ask sys-boot/elilo
Its configuration file is called /etc/elilo.conf and a sample file is installed in the typical docs directory (/usr/share/doc/elilo-<version>/). Here is another sample configuration:
boot=/dev/sda1 delay=30 timeout=50 default=Gentoo append="console=ttyS0,9600" prompt image=/vmlinuz label=Gentoo root=/dev/sda3 read-only image=/vmlinuz.old label=Gentoo.old root=/dev/sda3 read-only
The boot line tells elilo the location of the boot partition (in this case, /dev/sda1). The delay line sets the number of 10th of seconds before automatically booting the default when in non-interactive mode. The timeout line is just like the delay line but for interactive mode. The default line sets the default kernel entry (which is defined below). The append line adds extra options to the kernel command line. The prompt sets the default elilo behavior to interactive.
The sections that start with image define different bootable images. Each image has a nice label, a root filesystem, and will only mount the root filesystem read-only.
If, while building the Linux kernel, an initramfs was also configured to boot from, then it is necessary to change the configuration by referring to this initramfs file and telling the initramfs where the root device is at:
image=/vmlinuz label=Gentoo initrd=/initramfs-genkernel-ia64-3.16.5-gentoo append="initrd=initramfs-genkernel-ia64-3.16.5-gentoo root=/dev/sda3 console=ttyS0,9600" read-only
When the configuration is done, run elilo --efiboot. The
--efiboot option adds a menu entry for Gentoo Linux to the EFI Boot Manager: