Loading Linux Images to a Compact Flash Disk
When changing firmware images or creating custom firmware images for your Compact Flash-based machine, it is necessary to perform a few steps to load the firmware image onto the CF card.
To perform this procedure, you will need to have the following items:
- The Compact Flash card you wish to use to hold the firmware.
- A Compact Flash card reader attached to your computer.
- The firmware image.
- A fully functional Linux desktop.
- The package management tools installed:
tar, and either
bzip2(depending on the image).
- The EMAC package which provides the
README.TXTfile in the package details out the steps needed to install the script properly.
put-image script, and its associated tools, can be downloaded from EMAC's Subversion Repository.
The script and its tools can be downloaded, if you have svn (Subversion) installed, by running the following command in a terminal:
svn co https://svn.emacinc.com/public/EMAC-OE-2009.03-STABLE/trunk/contrib/put-image/
When you run the above command, you should see something like this:
developer@ldc:~$ svn co https://svn.emacinc.com/public/EMAC-OE-2009.03-STABLE/trunk/contrib/put-image/
A put-image/date2stamp A put-image/stamp2date A put-image/datediff A put-image/put-image A put-image/lilo-22.8.sbin.static.tgz A put-image/README.TXT Checked out revision 175.
|WARNING: Performing the following procedure incorrectly can cause a catastrophic loss of data. The individual steps should be carefully studied prior to attempting the procedure for the first time.|
EMAC cannot be responsible for the loss of data which may result from incorrectly following this procedure. EMAC strongly recommends having a current backup of the data on your computer before attempting this procedure. Use it at your own risk.
Perform the following steps to load the firmware onto your Compact Flash card:
- Insert the Compact Flash card into your card reader.
- Navigate (from within the shell) to the directory which contains the firmware image you wish to use.
- Determine where the Compact Flash card was mounted:
developer@ldc:~$ dmesg | tail -n 10 [23236.042944] sdc: detected capacity change from 4110188544 to 0 [23243.783467] sd 12:0:0:0: [sdc] 8027712 512-byte logical blocks: (4.11 GB/3.82 GiB) [23243.785199] sd 12:0:0:0: [sdc] No Caching mode page present [23243.785204] sd 12:0:0:0: [sdc] Assuming drive cache: write through [23243.787314] sd 12:0:0:0: [sdc] No Caching mode page present [23243.787326] sd 12:0:0:0: [sdc] Assuming drive cache: write through [23243.790625] sdc: sdc1[23244.290093] kjournald starting. Commit interval 5 seconds [23244.293646] EXT3-fs (sdc1): using internal journal [23244.293651] EXT3-fs (sdc1): mounted filesystem with ordered data mode developer@ldc:~$
The output of the
dmesg command tells us that the Compact Flash card, in this case, was mounted on
/dev/sdc1, and that its device node is
/dev/sdc. NO, the preceding sentence is incorrect. Inspect the output shown above to see where this information came from. The
/dev/ prefix will go before the device name, but is not shown in the output. The letters you are looking to see will start with either
hd. The third letter will specify which of these devices is assigned to the CF Card.
- At this point, it is wise to double check to ensure you have the correct device node for the Compact Flash card. Specifying the wrong device node could cause a complete loss of data on your hard drive. It is very important to be extremely careful when specifying the device node for the Compact Flash.
/dev/sdc1as our example device node, type the following command:
developer@ldc:~$ mount | grep sdc1 /dev/sdc1 on /media/EMAC-OE type ext3 (rw,nosuid,nodev,uhelper=udisks)
This shows us that the device node,
/dev/sdc1, is in fact our Compact Flash card. We know this because:
- It is not mounted on one of the standard Linux filesystem mountpoints, such as
- It is mounted in the
/mediadirectory, where we expect it. We may alternatively expect to see it mounted in
/mnt, depending upon the configuration of the Linux distribution in use.
|NOTE: Not all Linux distributions will have |
For those unfamiliar with the term
fdisk -lto inspect the device node:
developer@ldc:~$ sudo fdisk -l /dev/sdc Disk /dev/sdc: 4009 MB, 4009549824 bytes 77 heads, 56 sectors/track, 1816 cylinders, total 7831152 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00090707 Device Boot Start End Blocks Id System /dev/sdc1 62 7831151 3915545 83 Linux developer@ldc:~$
|NOTE: The |
|TIP: As can be seen from the output of the |
- The device to specify for the boot argument must also be determined prior to putting the image onto the Compact Flash card. If you downloaded the firmware image from EMAC, there should be a text file associated with the image which tells you which device to specify for this. If you have built your own custom image, you should use the same boot device as you used with firmware from EMAC. In this example, we're using hardware which specifies /dev/hdc for the boot device.
- Now, run the put-image script:
developer@ldc:~$ /path/to/put-image --root=/dev/sdc --boot=/dev/hdc emac-firmware-image.tar.gz