x86: GRUB-Based Booting

This system performance enhancement is new in the Solaris Express 6/05 release.

The Solaris OS is now loaded with the open source GRand Unified Bootloader (GRUB). GRUB is responsible for loading a boot archive, which contains the kernel modules and configuration files, into the system's memory. The Solaris kernel boots based on the contents of the in-memory boot archive.

Because the Solaris kernel is fully compliant with the Multiboot Specification, you can boot the Solaris OS on an x86 based system by using GRUB. With GRUB, you can more easily boot the various operating systems that are installed on your system. For example, on one x86 system, you could boot the following operating systems:

• Solaris OS

• Linux

• Microsoft Windows

A key benefit of GRUB is that it is intuitive about file systems and kernel executable formats. This feature enables you to load an operating system without recording the physical position of the kernel on the disk. With GRUB-based booting, the kernel is loaded by specifying its file name, the drive, and the partition where the kernel resides.

One notable change is the replacement of the Device Configuration Assistant (DCA) with the GRUB menu. When an x86 based system boots, the GRUB menu is displayed. From this menu, you can select an OS instance by using the up-arrow and down-arrow keys. If you do not make a selection, the default OS instance is booted.

The GRUB-based boot feature provides the following improvements:

• Faster boot times on x86 based systems

• Installation from USB CD or DVD drives

• Ability to boot from USB storage devices

• Simplified DHCP setup for PXE boot with no vendor-specific options

• Elimination of all realmode drivers

In addition, the following two administrative commands have been added to assist with managing system bootability:

bootadm

This command rebuilds the boot archive.

installgrub

This command installs GRUB boot blocks.

As a part of this functionality, x86 based systems must have a minimum of 256 Mbytes of RAM to boot and install the Solaris Express 6/05 release.

For more information about these enhancements, see System Administration Guide: Devices and File Systems and System Administration Guide: Basic Administration. See also the bootadm(1M), grub(5), and installgrub(1M) man pages.

See the following resources for additional installation information:

• For new booting information about installing with the Solaris interactive installation program, see the Solaris Express Installation Guide: Basic Installations.

• For new booting information that affects setting up an install server and installing over the network, see the Solaris Express Installation Guide: Network-Based Installations.

• For new booting information about installing with the custom JumpStart program, see the Solaris Express Installation Guide: Custom JumpStart and Advanced Installations.