[syslinux] Custom CentOS DVD, isolinux.bin, and isohybrid...

[Bernd Blaauw]

Op 22-6-2012 13:20, Trey Blancher schreef:
> I was given a custom CentOS 5.4 DVD, containing some Digium software for one of our customers.

I guess upgrading/replacing CentOS 5.4 is out of the question, even with 
6.2 and 5.8 released.

With recent Isolinux versions, an Isohybrid file doesn't care in which 
way it's booted (as CD, virtual CD or as raw harddisk image). The Linux 
kernel won't care much either, but any initrd or init scripts included 
with old distributions might not be able to handle booting from USB 
Flash Device. In other words, the script loads drivers for whatever 
interface an optical device would be connected to, then looks for the 
medium (CD/DVD/Bluray) to find its needed data.

I suppose all of the following already worked for you:
1) ripping the disc
2) booting the disc
3) remastering the disc (contents) and verifying it's bootable
4) updating Isolinux and remastering + booting

You might want to have a look at how a mini distro like PartedMagic 
handles booting and mounting ISO files from USB flash drive or even 
system memory (Syslinux's MEMDISK component). Or more recent CentOS 
incorporates these changes, perhaps allowing you to backport specific 
scripts.