Spectris Arcom VIPER Quick Start Manual page 19

VIPER RedBoot and AEL Quickstart
The file system
The file system used on the VIPER Flash is a compressed Journaling Flash File
System (JFFS2). JFFS2 has the following advantages:
•
Robustness.
•
Power fail safe.
•
No integrity scan (fsck) is required at boot time.
•
Flash wear levelling.
•
Transparent compression, with a typical compression ratio of 2:1.
The on-board Flash is partitioned using RedBoot FIS, as shown in the following table:
Partition #
0
1
2
Previous versions of Arcom Embedded Linux on the VIPER made use of a
separate kernel partition. From version 4 issue 1 onwards, the kernel is stored
as a regular file in the /boot/ folder on the root filesystem.
In addition, a 4MB RAM-based file system is mounted on /var/tmp for temporary files.
These are lost on reboot.
The basic AEL install uses about 7.9MB of physical Flash. On a board with 32MB of
Flash memory fitted, this leaves about 24.1MB free. This is about 50MB of free space,
assuming a typical 2:1 compression ratio. You can make additional space available by
removing unused packages. For more information, refer to the AEL Technical Manual,
which is in the /manuals/ folder on the Development Kit CD.
The default Flash image is on the Development Kit CD, in the /images/ folder. For an
explanation of how to reload a complete Flash image, see the AEL Technical Manual.
© 2005 Arcom Issue D
Block device Size (KB)
/dev/mtdblock0 124
/dev/mtdblock1 4
/dev/mtdblock2 remainder
Arcom Embedded Linux (AEL)
Offset (KB) Description
0 Partition table
124 RedBoot configuration
128 Root file system
19