[syslinux] Plop Boot Manager quit working with 5.10

[Ady]

> I have updated syslinux in Parted Magic's test version to the 5.10 release.
> With 4.06 I booted plop like this:
> 
> LINUX /boot/plpbt/plpbt.bin
> 
> Now it says /boot/plpbt/plpbt.bin... ok
> Booting kernel failed: Invalid argument
> 
> Other "extras" like IPXE, HDT, memtest86+, chntpw, Super Grub Disk, etc...
> all work with 5.10. Revert to 4.06 and plop works again.
> 
> Is this a problem with syslinux or plop?
> 
 
Testing under VBox 4.2.14, Syslinux 6.01-pre5, BIOS, ISOLINUX, 
menu.c32:

LABEL plop_test
MENU LABEL PLoP Boot Manager V5.0.15-TEST
COM32 linux.c32
APPEND plpbt_test.bin

fails with:
syslinux_boot_linux() failed: Error 22
linux.c32 failed: Boot aborted!

and

LABEL plop
MENU LABEL PLoP Boot Manager V5.0.14
COM32 linux.c32
APPEND memdisk initrd=plpbt.img.gz

successfully boots PLoP.

Note the different PLoP versions (stable / test), and that one 
Syslinux entry uses the PLoP kernel and the other uses the image with 
memdisk.

I have not tried without using linux.c32.

I have not actually tried to go on with additional booting steps to 
boot something else, from inside PLoP itself.

It might be worth testing Syslinux 5.11-preN too (instead of 5.10) 
with different versions of PLoP, and with and without MEMDISK.

Regards,
Ady.