[syslinux] Boot fails in a VMware player VM - syslinux 6.03

[Thomas Schmitt]

Hi,

> I forgot to post-process the ISO image you downloaded,
> I've now uploaded a new one, post processed with "isohybrid -u".
> ...
> MBR partition path :   2  /isolinux/efiboot.img
> ...
> GPT partition path :   2  /isolinux/efiboot.img
> ...
> Unfortunately I am unable to decipher that and analyze the differences
> with the output of that command applied to debian-7.5.0-amd64-netinst.iso.

The previously missing entry points for the UEFI boot image
are now present in MBR and GPT.
The main difference of the ISO 9660 boot pointers to the Debian image
is the lack of Apple Partition Map (which i deem surplus in Debian
anyway).

Except the fact that you try using SYSLINUX for UEFI, the boot
equipment now looks much like the ISOs of Archlinux.


> I saw this message output of gdisk:
>  "Warning! Main partition table overlaps the first partition by 34 blocks!"

This is a (hopefully harmless) consequence of the partition layout
as invented and implemented in the isohybrid program by Matthew
Garrett (see also http://mjg59.dreamwidth.org/11285.html).
 
The problem is in the fact that GPT partition 1 begins at
block 0, whereas the partition table itself begins at block 1.
As stated before, boot firmware is more tolerant towards our
jackalope ISOs than are partition editors.

I downloaded slint64-14.1.iso:
GPT Partition 1 marks the whole ISO filesystem and is mountable
as ISO
> GPT                :   N  Info
> ...
> GPT start and size :   1  0  89605

Partition 2 marks the UEFI boot image and is mountable as FAT
> GPT start and size :   2  188  2880

So the whole ISO is protected from partition editors
and both filesystems can be mounted. But from the view of a
partition editor, this is just a nasty mess.


The ideas of GRUB2's author Vladimir Serbinenko differ from
those of isohybrid by a neater partiton layout. Partition editors
love it.
But those neat partitions cannot be used for mounting the ISO,
because none of them starts where the ISO filesystem begins. 

Example from an ISO which stems from script grub-mkrescue:
> GPT start and size :   1  64  356
> GPT start and size :   2  420  128
> GPT start and size :   3  548  116
Partition 1 begins at block 64 and has 356 blocks. It is just
a placeholder to mark this area as occupied.
Seemlessly adjoining is partition 2, which points to the UEFI
boot image (FAT).
Partition 3 occupies the rest of the ISO image (which is very
small).


Have a nice day :)

Thomas