making available usb usable iso's without using livecd-iso-to-disk or liveusb-creator

Jeremy Katz katzj at redhat.com
Mon Apr 13 02:44:36 UTC 2009


On Sunday, April 12 2009, Till Maas said:
> On So April 12 2009, Kevin Kofler wrote:
> > psmith wrote:
> > > like i said it was brought up that liveusb-creator and
> > > livecd-iso-to-disk were available, but both of these are additional
> > > packages and incur resource usage where as releasing an iso that is both
> > > usb and cdr compatible saves resources
> >
> > Actually, making a hybrid ISO wastes the resource which is most valuable:
> > disk space on the live CD! We're always very much at the limit of the live
> > CD size, we have no room for extra USB stuff.
> 
> Is this really the case? By accident I found that the isolinux package 
> contains a isohybrid shell script which modifies existing iso images to be 
> hybrid. It only writes to the MBR, which is filed with nullbytes in the F11 
> Beta iso image and pads the image to a fake cylinder boundary. This makes the 
> image only around 600KB larger, but I guess even these 600KB can still be used 
> by the filesystem. The only problem I currently see, is that it seems to 
> conflict with the implanted md5 checksum.

It's on my list to look at, but its existence was a little late for F11.
The conflict with the implanted md5 makes me a little sad inside, but
maybe we can come up with a good way to do both.  The other thing it
seems somewhat likely to conflict with is dual-mode MBR/EFI boot CDs
which we also want to support.
 
> > liveusb-creator is the more useful method, as it allows you to control your
> > overlay size and share the USB stick with other stuff.
> 
> The problem with live-iso-to-disk is, that it is not functional on F10 to 
> create F11 live USB media, because it requires a F11 syslinux package. To 
> create testing live USB media, it would be a lot better if it was possible 
> just to use the latest Fedora Stable release to create bootable test media, 
> which should be always possible to use dd or cat with the hybrid iso.

There's a hacked livecd-iso-to-disk.sh in git and on my fedorapeople
page[1] that feedback on would be helpful.  Assuming it works, then
we'll probably push the hack back to older releases.  I was hoping to
find something better, but so far, no dice :/

Jeremy

[1] http://katzj.fedorapeople.org/livecd-iso-to-disk.sh




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