Custom Centos 7 ISO
 

Hello,

I getting frustrated by trying to customize a Centos install cd.
Every attempt results in a "kernel panic unable to mount root fs on unknown block(2,0)" when I try to boot from the iso.By troubleshooting I did found that the problem is linked to the initrd.img in the /isolinux folder. With the original initrd.img my customized iso boots correctly.But I also need to customize initrd.img.

This is what I do and it fails (even without modifying the content of initrd.img)... :

1. copy content iso to a tmp/centos folder

1. cp /tmp/centos/isolinux/initrd.img /tmp/initrd.img.xz

1. cd /tmp

1. xz -d initrd.img.xz

1. xz (-9) initrd.img

1. cp initrd.img.xz /tmp/centos/isolinux/initrd.img

1. chown 500 /tmp/centos/isolinux/initrd.img

1. chgrp 502 /tmp/centos/isolinux/initrd.img

1. mkisofs....

The problem happens somewhere in bold I think... :). Because if I recreate my iso file without decompressing / compressing the initrd.img file, it works correctly.
I lose 2Mb of data between the original initrd.img and xz decompress/compressed version..., a diff between (lsinitrd of both files) only reveals a difference on total size. What am i missing here?

Why are you modifying the initrd.img? You should only need to modify the squashfs and not touch the initrd.

what are you trying to do ?
what is being changed in the "initrd.img" ?

Hello,

Thanks Sag47, I was a confused and you are right, the correct approach is to only modify the squachfs.img .

I'm modifying the "rootfs.img/initrd.img(centos6)" to add some scripts that are needed for a kickstart install. These scripts are called in the %pre section of the ks.cfg.

Thanks all for the help