Custom Centos 7 ISO

[lodiablo]

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)... :
-copy content iso to a tmp/centos folder
-cp /tmp/centos/isolinux/initrd.img /tmp/initrd.img.xz
-cd /tmp
-xz -d initrd.img.xz
-xz (-9) initrd.img
-cp initrd.img.xz /tmp/centos/isolinux/initrd.img
-chmod 500 /tmp/centos/isolinux/initrd.img
-chgrp 502 /tmp/centos/isolinux/initrd.img
-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?

[TrevorH]

I think you meant chown not chmod...

[lodiablo]

I think you meant chown not chmod...

Yes, you are correct
Do you have a idea what the solution could be?
Cheers

[spstarr]

Having exactly the same problem you're having, the secret is you must use -C crc32 for recompressing the initrd.img with XZ, then it should work for you

Thanks,
Shawn