[SOLVED] Beta1 ISOs, are they 'hybrid'?

[wobo]

I usually dd the ISO to an USB key to install on my notebook and netbook. First to not waste optical media, second because the netbook has no optical drive.
This worked fine with the alphas.

My question:
Did something go wrong when "burning" the ISO on the key or are the ISOs not 'hybrid' ?

Code: Select all

# dd if=mageia-dvd-1-Beta1-x86_64.iso of=/dev/sdh
8300544+0 Datensätze in
8300544+0 Datensätze out
4249878528 Bytes (4,2 GB) copied, 1300,8 s, 3,3 MB/s

but the key will not boot.
What strikes me is that fdisk does not see the ISO:

Code: Select all

# fdisk -l
Platte /dev/sda: 1000.2 GByte, 1000204886016 Byte
[....]
Platte /dev/sdh: 15.6 GByte, 15599771136 Byte
64 Köpfe, 32 Sektoren/Spur, 14877 Zylinder
Einheiten = Zylinder von 2048 × 512 = 1048576 Bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/sdh has no valid partition table  <======


[wobo]

Found out: somehow dd did not work correct with the key - I did the whole thing again
- destroyed the partition table (after that diskdrake did not see the key and gparted was not able to set a partition table!)
- partitioned the key with cfdisk
- dd'd the ISO on the key

Now it boots.

Question answered: yes, the ISOs are hybrid.

[Ken-Bergen]

Wobo, you are correct that the ISOs are hybrid but the reasoning for your conclusion is flawed.
dd will create bootable USB sticks from non hybrid ISOs.
If you use Mandriva-seed however the ISO must be hybrid.

Ken

[wobo]

dd will create bootable USB sticks from non hybrid ISOs.

Oh, really? This is news, thx for enlightening me. Seems that I never really cared for the technical background because Mandriva's ISOs have been hybrid for a long time and I started using usb keys instead of cd/dvd at that time...

[ahmad]

I don't think dd'ing a non-hybrid ISO would make the usb key bootable; the ISO has to be hybrid for isolinux to be able to boot of off it.

From /usr/share/doc/syslinux/isolinux.txt (from the syslinux package):

++++ HYBRID CD-ROM/HARD DISK MODE ++++

Starting in version 3.72, ISOLINUX supports a "hybrid mode" which can
be booted from either CD-ROM or from a device which BIOS considers a
hard disk or ZIP disk, e.g. a USB key or similar.

To enable this mode, the .iso image should be postprocessed with the
"isohybrid" script from the utils directory:

isohybrid filename.iso

This script creates the necessary additional information to be able to
boot in hybrid mode. It also pads out the image to an even multiple
of 1 MB.

This image can then be copied using any raw disk writing tool (on Unix
systems, typically "dd" or "cat") to a USB disk, or written to a
CD-ROM using standard CD burning tools.

The ISO 9660 filesystem is encapsulated in a partition (which starts
at offset zero, which may confuse some systems.) This makes it
possible for the operating system, once booted, to use the remainder
of the device for persistent storage by creating a second partition.

[wobo]

Thx ahmad, this was what I knew about the matter. That's why I was surprised to read what ken wrote.

[Ken-Bergen]

Thx ahmad, this was what I knew about the matter. That's why I was surprised to read what ken wrote.

Yes Wolfgang, you were correct.
I just had blond/CRS moment and mixed the all.img which is what I use most with the ISOs.

Ken