14.4.2. How to Increase the Size of the Ramdisk

1. Extract compressed ramdisk image (ramdisk.gz) from U-Boot image:

   bash$ dd if=uRamdisk bs=64 skip=1 of=ramdisk.gz
   21876+1 records in
   21876+1 records out
   

2. Uncompress ramdisk image

   bash$ gunzip -v ramdisk.gz
   ramdisk.gz:      66.6% -- replaced with ramdisk
   

3. Mount ramdisk image
   As root:

   bash# mkdir -p /mnt/tmp
   bash# mount -o loop ramdisk /mnt/tmp
   

4. Create new ramdisk image, say 8 MB big:

   bash$ dd if=/dev/zero of=new_ramdisk bs=1024k count=8
   bash$ /sbin/mke2fs -F -m0 new_ramdisk
   bash$ /sbin/tune2fs -c 0 -i 0 new_ramdisk
   

   As root:

   bash# mkdir -p /mnt/new
   bash# mount -o loop new_ramdisk /mnt/new
   

5. Copy files from old ramdisk to new ramdisk:
   As root:

   bash# cd /mnt/tmp
   bash# find . -depth -print | cpio -VBpdum /mnt/new
   

   Now you can add, remove, or modify files in the /mnt/new directory. If you are done, you can re-pack the ramdisk into a U-Boot image:
6. Unmount ramdisk images:
   As root:

   bash# umount /mnt/tmp
   bash# umount /mnt/new
   

7. Compress new ramdisk image

   bash$ gzip -v9 new_ramdisk
   ramdisk:         66.6% -- replaced with new_ramdisk.gz
   

8. Create new U-Boot image (new-uRamdisk)

   bash$ mkimage -T ramdisk -C gzip -n 'New Simple Embedded Linux Framework' \
   > -d new_ramdisk.gz new_uRamdisk
   Image Name:   Simple Embedded Linux Framework
   Created:      Sun May  4 13:23:48 2003
   Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
   Data Size:    1400121 Bytes = 1367.31 kB = 1.34 MB
   Load Address: 0x00000000
   Entry Point:  0x00000000
   

Remember that Linux by default supports only ramdisks up to a size of 4 MB. For bigger ramdisks, you have to either modify your LInux kernel configuration (parameter CONFIG_BLK_DEV_RAM_SIZE in the "Block devices" menue), or pass a "ramdisk_size=" boot argument to the Linux kernel.