[CentOS] USB install annoyances

[Phoenix, Merka]

-----Original Message-----
From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On Behalf Of m.roth at 5-cent.us
Sent: Tuesday, 10 January, 2012 11:44
To: CentOS mailing list
Subject: Re: [CentOS] USB install annoyances

>> Darr247 wrote:
>> >> But this thread's gotten way OT: *does* anyone have any idea what the 
>> >> .img file is that the running o/s from install.img is looking for, 
>> >> after the partitioning, when it's ready to install?
>> >
>> > Possibly, but without the info I previously requested, I won't be 
>> > trying to reproduce the problem.
>> >
>> > e.g.
>> > the source file[s] and command[s] used to make your bootable USB stick.

>> I started by listing that:
>> 1. I have a partitioned USB stick, 8G, with a 10M FAT32 partition, and the rest as ext3.
>> 2. Rsync'd isolinux to the FAT partition, renamed isolinux.cfg to syslinux.cfg
>> 3. syslinux to the USB
>> 4. mounted DVD.iso, and rsync'd all of that to the ext3 partition.
>> 5. mounted the second DVD, and rsync'd Packages/* to the Packages directory already there, and so have a 1 DVD, effectively, on the USB.
>> 
>> But the question is what image# 1 that it's looking for? It's not trying to look on the USB for an .iso, is it?
>> 
>>         mark

Ah!

Take a look at the README in the /images/ directory on the DVD media.

"The diskboot.img file is a VFAT filesystem image that can be written to a
USB pendrive or other bootable media larger than a floppy.  Note that
booting via USB is dependent on your BIOS supporting this.  It should
be written to the device using dd."

diskboot.img will be the bootable filesystem (for your 10M FAT32 partition).
Even tho you rsync'ed (copied) files over, there may be additional pieces missing (for example, the boot block) that are not contained as files per se. Checking the 'diskimage.img' with the file utility identifies the file type as:

x86 boot sector, code offset 0x58, OEM-ID " mkdosfs", sectors/cluster 4, root entries 512, sectors 24576 (volum
es <=32 MB) , Media descriptor 0xf8, sectors/FAT 24, heads 64, serial number 0x4d9277bd, label: "           ", FAT (16 bit)

It may contain another filesystem after that, but the very first part is a bootblock.

Think of 'diskboot.img' as the /boot partition and 'stage2.img' as the / (root) partition, for the Linux operating system environment in which the installer runs. The installer runs in a text-mode for a little bit, but switches over to a graphical (or near-graphical) version on the second stage (where you will see all the packages being installed). The graphical version of the installer relies on this second stage heavily, as the filesystem contains most of the libraries (and all of the fonts) required to run X/Windows environment.

Poking around the DVD media, shows a kernel (vmlinuz) and an initrd.img in the /isolinux directory, but very little else to actually run a Linux operating system (X/Windows, and the command line shell interpreters). The second stage contains a pre-built root filesystems that contains the bare minimum to get a system up and running so that RPM can operate, as well as a minimal X/Windows environment for the graphical version of the installer, LVM and other partitioning tools. It may even contain files that are not copied over to the hard drive but are required by the installer itself to run.


Hope this helps explain it :-)

Cheers!

Simba
Engineering