[syslinux] How to use --once? Does it work?

[Ady]

> 
> To be clear, I am not saying there is no bug - there might be.
>  
 
I performed the following test with several versions of Syslinux:

1_ Execute:
 'extlinux --once=non_default_label --install /mnt/sda1' ;
2_ In first reboot, the "non_default_label" should be executed;
3_ In second reboot, the default label should be executed.

Results:
_ 4.05 to 4.07: OK.
_ 5.00-pre1 to 5.00-pre7: fail.
_ 5.00-pre8: step #2 OK, step #3 buggy.
_ 5.00-pre9 to 5.11-pre9: OK.
_ 6.xx and 6.xx-pre*: fail.

Considering that the branches were developed simultaneously, I am 
guessing that at least in one of the merging commits some (sort of) 
conflict/error migth have pass through without detection.

In particular, there are several merging commits after 5.00-pre8, 
after 5.00-pre9 (both "--once" OK) and 6.00-pre1 ("--once" failure). 
Some of those merging commits included conflicts, and during the same 
period there is at least one "Fixup merge botch" commit 
( 
<http://git.zytor.com/?p=syslinux/syslinux.git;a=commit;h=afd28c08dc76
153efcd9f760bcdbeaabda74eb05> )

which happens to be related to libinstaller.

It should be noted that there are later commits affecting the ADV 
too.


Additionally, the "efi/adv.c" file in 6.03-pre13 states:
 *** 
 Core ADV I/O
 Code consolidated from libinstaller/adv*.c and core/adv.inc with the
 addition of EFI support
 *** 

So although currently the unexpected behavior can be seen under BIOS, 
there is a chance that the solution might still be under the "efi/" 
subdirectory.

Regards,
Ady.