[syslinux] port syslinux isohybrid perl script to C

[Thomas Schmitt]

Hi,

my reply is split in two parts on two threads:
- This one is about the fundamental aspects of
  my proposal.
- The other one is about implementation details
  and follows in a separate mail.


> >   http://syslinux.zytor.com/archives/2010-March/013905.html
> That doesn't work, since creating the content of the MBR requires
> knowing the content (at the very least the size) of the iso image; as
> such, it belongs in the iso generator.  It cannot be pre-generated as a
> template.

Yes. Those two infos are in the realm of
libisofs.
But everything else belongs to syslinux in my
eyes. Including all user options of isohybrid.


> There really is nothing at all in bytes 432..511 that xorriso/libisofs
> can't create based on defaults plus user options; the rest of the System
> Area file just comes out of the Syslinux build as a plain binary.

The defaults are syslinux realm too.

I would prefer to only insert the size and
address information and get everything else from
the MBR template. The current implementation in
libisofs knows too much about syslinux 3.72.
That causes concern (if not pain) on both sides.

Therefore i propose to have a program in syslinux
that prepares MBR templates at the user's wish.

The less libisofs has to know about MBRs,
the more freedom syslinux has for its own
development.


> Note: the patching of the boot file LBA is really just a convenience.
> [...]
> Then the *only* difference between isohybrid
> and -G would be the creation of the partition table.

It is not overly inconvenient as long as we have
to insert the size information into the partition
table, anyway.
Actually the LBA is the easiest part of the job.


> the System Area is big enough that it
> could contain a full-blown El Torito boot catalog parser, if you think
> that is a better option.

It sounds attractive from the view of ISOLINUX
architecture. There would be no chance for
contradicting LBAs any more.

>From the view of libisofs there is not much
difference. So my opinion is neutral here.

The decisive point that needs coordination is
the partition table.


Have a nice day :)

Thomas