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jhess

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Posted - 24 Apr 2008 :  07:39:16  Show Profile  Email Poster

Debian JFFS2 2008-04-22 (armel)

Debian JFFS2 (armel) 2008-04-22 is a root file system that is derived from the Debian (armel) distribution and is trimmed down to fit (compressed) in a partition in on-board flash as small as 15MB. This size can be reduced further by removing the demo programs and associated data that are included in this distribution.

EABI is a new application binary interface (ABI) for Linux that offers performance improvements over the old ABI through use of softfloat instructions for floating point arithmetic, a more efficient syscall convention, and the option to use VFP hardware if the CPU has it. See the EABI FAQ for details.

While EABI has its advantages, this release has the following issues:
  • It is not as well tested or as stable as the regular Debian arm system.
  • It is based on Debian unstable, not on Debian testing, which may make it harder to maintain than our arm releases.


The ADS Debian JFFS2 root uses x11 (XFree86) as its GUI and includes several demo programs that run under x11. The media files for several of these demos are stored in the /usr/share/ads/demo_media directory. Many common x11 shared libraries are included in the JFFS2 root, including those necessary to run gtk programs.

The JFFS2 filesystem is a persistent flash filesystem that keeps changes across reboots - it is not always the same on each boot (like the ramdisk). Although it is designed to be resilient in the case of power loss and unclean shutdown/dismount, you should shut down your JFFS2 system properly (using the 'shutdown' command) to cleanly unmount the root filesystem.

The following files are included in this release:
700050-41133.partno
MD5SUMS
README.txt
cmdline.txt
cmdline_bitsyx.txt
debian-jffs2.tar.gz
flashfs1
register.txt
register_agxepson.txt
register_vgx.txt
snapshot.txt


128k flash:

700050-41163.partno
MD5SUMS
README.txt
flashfs1


Usage
Download the flashfs1 image and copy it to an ATA flash card.

If your flash has 128k blocks (most ADS systems have 32 bit wide flash from 2 chips in parallel; these boards have 256k blocks, but a few systems like the BitsyG5 and Portal have 16 bit wide flash and a block size if 128k), download the flashfs1-128k image instead.

Also copy onto the card the kernel zImage file for the kernel you want to use. Note that you must use an EABI version of the kernel, such as the one provided here.

For systems such as the BitsyXb, BitsyG5, TurboXb, Sphere, VIX, Portal, and VGX, which use the u-boot bootloader, a set of u-boot configuration files is needed. See this topic for all the available files, download the appropriate files and copy them to the card. Note that you will need at a minimum start.txt, jffs2 root_config.txt, and a tty_config.txt file for your system. A hw_config.txt file for your system's frame buffer is recommended for best performace of the video demonstration programs included in this distribution.

For PXA systems such as the BitsyX, AGX, and GCX, which do not use the u-boot bootloader, a kernel command line is required to direct the kernel to mount this file system during start up. Download a cmdline.txt file as shown below and copy it to the card, then create a file named ProgramFlash.ads! on the card. A register.txt file is recommended for best performace of the video demonstration programs included in this distribution. Download the register.txt file for your system's frame buffer as shown below and copy it to the card.

Now boot your system. The bootloader will erase everything in on-board flash (except the bootloader itself) and program (copy) the images on the ATA card to on-board flash. The kernel will be loaded from on-board flash and the JFFS2 root file system will be mounted when Linux starts.

Note that the first boot of a JFFS2 filesystem includes a delay at the beginning when the kernel initialises the flash memory. This is a one-time delay, subsequent boots will be faster.

Remove the ATA flash card to prevent an unnecessary erase/reprogramming of on-board flash the next time you reboot. See the bootloader manual for more information.


Command lines
These command lines will eliminate the ramdisk partition and direct the kernel to mount the JFFS2 root file system in the third partition. See the bootloader manual for more examples.

On the BitsyX, use this cmdline.txt.

On AGX and GCX use this cmdline.txt.


Register Settings
These register.txt files will change the default 8bpp color depth to 16bpp. The bootloader reads the register.txt file and changes the registers before the kernel starts. Download the one for the frame buffer that is used by your board.

register.txt for PXA frame buffer and LQ64343 LCD (BitsyX, GCX, or AGX without an Epson chip)

register.txt for Epson frame buffer and LQ64343 LCD (AGX with an Epson chip)

register.txt for SM501 frame buffer and LCD or CRT (VGX)


Tar Archive
Here is a tar archive of the contents of the jffs2 image.


Verification
MD5SUMS and MD5SUMS (128k) provide MD5 checksums for all files in this release.


History
This release of our JFFS2 root filesystem is derived from the Debian armel port and superscedes our previous 2007-08-27 release.

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