[syslinux] SYSLINUX 3.81-pre10

[H. Peter Anvin]

Thomas Schmitt wrote:
> Hi,
> 
> while studying isohybrid.bin of 3.81-pre10
> i wonder whether isohybrid 3.72 and 3.81 are
> crosswise compatible with the isolinux boot
> images of 3.72 and 3.81.
> 
> I.e would this be technically ok in both
> isohybrid scripts ? 
> 
>   if ($ibsig ne "\xf7\xe3\xef\x0d" 
>       && $ibsig ne "\xfb\xc0\x78\x70") {
>       die ...
>   }
> 
> A "yes" would be very convenient to me:
> - libisofs would immediately be able to
>   create an MBR for a 3.81 image.
> - the future libisofs MBR generator with
>   user options would be able to support
>   the older boot images of 3.72 to 3.80.
> 

They aren't, unfortunately.  If they were I wouldn't have changed the
magic number.  A "yes" would be convenient to a lot more people, and I
thought hard about it... but it seems really messy to do.

What's worse is that the old MBR is actually broken even with the old
code, and I would have to spend some fairly serious time debugging what
the old images actually did.  If I find the time to do that I might be
able to come up with some kind of hack.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.