[syslinux] com32 module compatibility between 5.x versions

[Pete Batard]

Hi Rich,

On 2013.08.09 20:23, Rich Mahn wrote:
>    I do this all the time.  I put a number of ISOs on my USB--several
> versions each of Fedora, Centos, PartedMagic, AVG, SystemRescueCD, and
> others.  Putting just one distribution on it should be easier.  But if
> you want to have several, this is how I do it:

Thanks for the tips, but I already have the ISO -> USB conversion of 
Syslinux squared out, including figuring out how to reuse the ISOLINUX 
config file. Also the goal is to create a bootable USB drive that is as 
close as possible as the original ISO content (i.e. without additional 
menus or unwanted files).

The way I do it right now for, which doesn't seem too different from 
what you advise, is link a lower level isolinux.cfg|syslinux.cfg from a 
/syslinux.cfg if one doesn't already exist, as well as append the 
directory. This indeed seems to work pretty well.

But my issue is that, if I go with upgrading ISOLINUX from the ISO 
altogether, I need to embed every possible .c32 module in my 
application. At the very least this will double its size. Plus there's 
no telling if some ISO might not be using a custom module that I 
wouldn't have embedded. Thus, it's a lot better to reuse what exists on 
the ISO, especially when the goal is to keep the USB as close to the 
original as possible.

Also it might be worth noting that Rufus is a Windows application.

> I can't say this will handle your situation, but I hope this at least
> outlines an approach that might work.

It does work, since it's not that different from the one I use (as far 
as ISOLINUX is concerned - but the app also supports booting from WinPE, 
bootmgr as well as pure DOS and pure EFI).

At any rate, thanks for posting your tips.


As to the rest of the discussion, I can only hope that future Syslinux 
versions will provide an easy means of checking a module's version.

I would also very much like to hear about the idea of appending a copy 
of ldlinux.sys into isolinux.bin.

While I reckon that this feature would probably only ever used by my 
app, and that existing Syslinux users might not be too happy about the 
resulting increase in size, my estimate is that at least 100,000 to 
200,000 people have used Rufus to convert ISOLINUX 4.x based ISOs to USB 
ever since the beginning of the year (I had my millionth download in 
late July). So I hope some for of compromise can be reached to also help 
these users with regards to 5.x.

Regards,

/Pete