[CentOS-docs] CentOS 7 "compose" process

Steven Falco sfalco at imaginecommunications.com
Thu Oct 30 18:42:07 UTC 2014


On 10/30/2014 02:28 PM, R P Herrold wrote:
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> On Thu, 30 Oct 2014, Steven Falco wrote:
> 
>> I asked on the -devel list, and the suggestion was to use this
>> list instead.
> 
> Well, not exactly.  You were told:
> 
>>> You're certainly welcome to create documentation. If you 
>>> request access on the -docs list with your proposal, the 
>>> people who oversee wiki access will work with you.
> 
> That is, you were invited to write documentation

Sure, and I am willing to do that, but first I have to
understand the process myself.

> Everyone wants to make this harder than it is [and not read 
> the syslinux (isolinux) documentation (... long ago I built 
> some custom install ISOs for a course I ran), and will not 
> experiment]  And no-one writes ...

Not trying to make it harder.  I've already successfully
taken the existing iso apart by similar methods to what
you show below.  Loopback mount, unsquash the squashfs.img
file to obtain the rootfs.img file, loopback mount that, etc.

I have done all that, and made my changes, and glued it all
back together again, and it even does what I want.

But I regard that approach as a kludge.  Sort of like using a
binary editor to modify a program rather than recompiling
from source.  It works, but it isn't pretty.

What I really want to do is learn how the rootfs.img was
created in the first place so I can regenerate it "the right
way".  And I am more than willing to write it up for the wiki.

But first, I need to find the tools and scripts that are used,
so I can understand the process.

> http://www.owlriver.com/issa/mk-grub-iso.sh.text
> http://www.owlriver.com/issa/isolinux-howto.text
> 
> The initrd has what you are interested in changing (perhaps) 
> to drop in a ks.cfg ... the rest -- can all be copied out of a 
> loop-mounted existing centos CD and dumped in the relevant 
> directory (./isolinux/), as part of the phase for the mkisofs 
> step
> 
> cd to a directory with an ISO in it
> mkdir loop
> sudo mount -o loop CentOS-7.0-1406-x86_64-Minimal.iso loop/
> cd loop/
> [herrold at centos-6 loop]$ ls -l isolinux/ | \
> 	awk {'print $5"\t"$9'}
> 
> 2048    boot.cat
> 84      boot.msg
> 281     grub.conf
> 34935964        initrd.img
> 24576   isolinux.bin
> 3032    isolinux.cfg
> 176500  memtest
> 186     splash.png
> 2438    TRANS.TBL
> 33127644        upgrade.img
> 155792  vesamenu.c32
> 4902656 vmlinuz
> 
> There is a bit more if EFI support is wanted, but again, read 
> and experiment
> 
> - -- Russ herrold
> 
> - --
> end
> ==================================
>  .-- -... ---.. ... -.- -.--
> Copyright (C) 2014 R P Herrold
>       herrold at owlriver.com  
>    My words are not deathless prose,
>       but they are mine.
> 
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