M-Systems Flash Disk Pioneers 91-SR-005-10-7L Booting Linux from the DiskOnChip

Using the DiskOnChip with Linux OS

5 Booting Linux from the DiskOnChip

Being able to boot Linux from the DiskOnChip makes it possible to use the DiskOnChip as the only disk in the system, holding the OS itself in addition to all other applications and files.

In order to make a block device bootable on Linux, the kernel and the Lilo program should be copied to the block device and a root file system needs to be created. Creating a root file system on Linux is necessary, as from this root file system the kernel is activating several programs, such as:

Init Initialize all processes

Swapo Activate swapping

n

Mount Mount the root and proc filesystems

Sh Shell

For further details refer to http://sunsite.unc.edu/LDP/ or type:

#zcat /usr/doc/HOWTO/Bootdisk-HOWTO.gz more

Warning: Notice that the DiskOnChip firmware (i.e. doc121.exb) collides with Lilo. This means that it is not possible to load Linux from the HDD after the original firmware is restored (see par. 5.1.4). This doesn’t mean that the HDD is non-functional. It only means that the alternate firmware (doc2.fff) needs to be reloaded (see par. 4.1).

If it is required to boot Linux from both the HDD and the DiskOnChip, it is necessary to use both pLilo and boot.b (provided with the TrueFFS driver). For further details, refer to Appendix II.

5.1 Creating a Root File System

5.1.1 Introduction

This section is based on Bootdisk-HOWTO and other experiments. Since each distribution has a different file location and different installations, it is possible that you won’t succeed in booting Linux the first time from the DiskOnChip. When you receive errors, follow each error and try to fix things, but reload Linux from the HDD and remount the DiskOnChip each time.

Note: There are several programs that create a root file system. It is not possible to say that any of them is complete right now, but they are worth trying. The following program is recommended:

Yard: Yard creates rescue disks (also called boot disks) for Linux. A rescue disk usually contains utilities for diagnosing and manipulating hard disks and file systems. It is used when it is not possible (or if it is not required) to boot from your HDD. This package contains mainly perl scripts. Refer to http://www.croftj.net/~fawcet/yard/.

Note: For a sample root file system, refer to the file /tmp/doc-driver/samplefs.txtwhich is part of the compressed file driver.tgz.

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