Quick and dirty – modifying Boel initrd files manually

Boel initrd files are actually compressed cramfs files. This is a menuscript for authoring and modifying these files, if needed. Assume the file in question is /tftpboot/install-initrd-i386.img:

cp /tftpboot/install-initrd-i386.img /tmp/
cd /tmp/
gzip -S .img -d install-initrd-i386.img
mount -o loop install-initrd-i386 /mnt
mkdir initrd
cd /mnt/
tar cf – . | (cd /tmp/initrd/ ; tar vxf -) # expect errors about time. It’s OK.

cd /tmp/
umount /mnt

Here you can modify the contents of /tmp/initrd for your needs. When done, continue.

mkcramfs initrd initrd.cramfs
cat initrd.cramfs | gzip -9 > initrd.modified.img

Now you can copy the file /tmp/initrd.modified.img to your /tftpboot directory.

Warning – Never delete your original initrd, in case you made a mistake and need to go back in time.


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