[syslinux] isohybrid and ISO images whose size is not a multiple of 2048 bytes vs. VirtualBox

Rich Mahn rich at lat.com
Fri Feb 20 09:51:02 PST 2015

Just a small correction:

Thomas Schmitt via Syslinux <syslinux at zytor.com> wrote:

> > > I expect the average waste to be a bit less than 16 MB.
> > Yes, but slightly misleading. For example, the "16MB average" is 
> > relevant for 255/63.
> We advise two geometries: -h 63 -s 32 and -h 255 -s 63.
> isohybrid behavior with the first one will not be changed.
> With the second one it would waste 16 MB in average.

The average waste in the second case is just under 12 MiB.  If
you assume random distribution of ISO sizes, you have to pad by
0, 1, 2, or 3 cylinders with equal probability.  That averages
to 1.5 cylinders, or 12,337,920 bytes, which is just under 12 MiB.

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