iso2flash img

[Luigi Rizzo]

On Thu, Mar 22, 2012 at 05:42:27PM +0100, Thomas Schmitt wrote:
> Hi,
> 
> Vitaly Magerya <vmagerya at gmail.com>:
> > > you might want to try to dd the iso image directly onto USB instead; there
> > > where talks that Ubuntu would support this starting at 11.10.
> 
> Da Rock <freebsd-hackers at herveybayaustralia.com.au>:
> > Nada. Tried that and it didn't work. I'm not sure how that would work given
> > that it uses isolinux to boot- ergo needs a cd to load the kernel. Maybe
> > some way to determine the install media?
> 
> The trick is called "isohybrid".
> It works by a DOS MBR which starts the same executable boot image
> that is pointed to by the El Torito boot catalog.
> If the ISO is on a hard disk (or alike), then the BIOS boots via MBR.
> If it is on an optical medium, then the BIOS boots via El Torito.

interesting. It does work for me indeed.
And it might be a nice trick for our images too, so we don't
have to build a memstick and an ISO image...

cheers
luigi

> The question is rather why it does not work for you.
> 
> I downloaded
>   ubuntu-11.10-desktop-i386.iso
> from
>   http://www.ubuntu.com/download/ubuntu/download
> and put it onto an USB stick (by a Linux machine, but that should not matter)
>   dd of=/dev/sdc if=ubuntu-11.10-desktop-i386.iso bs=2048
> Note that /dev/sdc is not the first partition but the whole USB stick.
> 
> This stick boots on amd64 hardware.
> After some waiting with sparse iconography i get to the question
> whether i want to try or to install. I choose to try and get a
> graphical desktop. From the icon list i start Firefox and google
> a bit via my internet router. All seems well.
> 
> 
> On FreeBSD, GEOM complains about the DOS partition alignment.
> Partition 1 starts at block 64.
>   fdisk -p /dev/da0
>   # /dev/da0
>   g c243 h255 s63
>   p 1 0x17 64 1423896
>   a 1
> Nevertheless these two commands work and open access to the image content:
>   mount -t cd9660 /dev/da0 /mnt
>   mount -t cd9660 /dev/da0s1 /mnt
> (The ISO has two superblocks and two directory trees.)
> 
> 
> Does your hardware boot from USB stick at all ?
> Is its firmware (U)EFI rather than BIOS ?
> 
> 
> Have a nice day :)
> 
> Thomas
> 
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