[syslinux] isohybrid boot from logical partition

[Duncan Elliot]

I've attempted to understand what the isohybrid tool is doing, specifically
with the "--partok" flag.
As far as I can see, this essentially trims off the first 3 bytes of the
custom isohybrid MBR image before applying it to the ISO.

Can anyone explain how this enables the ISO to "be happy" on a partition,
rather than whole disk?

And does anyone have suggestions for what modification I'd need to look at
to support this on a logical parttion?
Would the change be in the isohybrid tool, or (I'm guessing more likely) in
the actual MBR image that the tool writes over the ISO?


On 28 December 2016 at 19:06, Duncan Elliot <dmelliot at gmail.com> wrote:

> Hi,
>
> I have been attempting to set up a multi-boot USB stick (i.e. multiple
> bootable ISO images on the one stick)
> I have had good success by:
> - processing ISO with isohybrid (with "partok" flag)
> - dd'ing ISO to primary partitions on the USB stick (e.g /dev/sdc2,
> /dev/sdc3, /dev/sdc4)
> - installing grub to USB stick and configuring to chainload to these
> partitions
>
> To remove the limit of 4 partitions, I would like to do the above but
> utilise logical partitions.
> All my tests to do this have failed, and generally result in the error
> message "isolinux.bin missing or corrupt." when trying to boot.
>
> Is this possible to achieve with current version of isohybrid?
>
> Any help on how to achieve this is appreciated.
>
> Thanks
> Duncan
>