Syslinux - Jul 2010 - Equivalent of pxechain.com for (USB key based) syslinux

Hello list,

I am trying to prepare a USB disk with syslinux that is meant to be able
to offer a choice among many different distributions. The goal is that I
should be able to dump each distribution's CD contents into a separate
subdirectory, and have a master menu that hands off to each
distribution's subdirectory.

A while back, when faced with a similar task on a PXE server, I came
across pxechain.com which elegantly solves this issue. With pxechain.com
I can say the following in my master pxelinux.cfg/default:

default menu.c32
prompt 0
menu title LGL PXE boot menu
timeout 100

LABEL KubuntuNet
        menu Kubuntu network install
        kernel pxechain.com
        append ::kubuntu904/netboot/pxelinux.0

LABEL udpcast
        menu label Udpcast
        kernel pxechain.com
        append ::udpcast/pxelinux.0

This correctly hands off to the (unmodified) pxelinux.cfg/default's in
the distribution's subdirectories. All KERNELs and initrds now use the
subdirectory (kubuntu904, udpcast) as their current directory, rather
than the original root directory.

However, how can I achieve the same thing with syslinux (for USB keys)?
There is MENU INCLUDE, but it doesn't change the current directory, so
the submenu file must be edited to prepend the subdirectory to every
kernel, initrd, display, function key, further submenues, ...

Thanks,

Alain

Alain Knaff <syslinux at misc.lka.org.lu> writes:
> However, how can I achieve the same thing with syslinux (for USB keys)?
> There is MENU INCLUDE, but it doesn't change the current directory, so
> the submenu file must be edited to prepend the subdirectory to every
> kernel, initrd, display, function key, further submenues, ...
LABEL udpcast
        menu label Udpcast
        config /udpcast/syslinux.cfg
        append /udpcast

But you will have a version mismatch between any modules (*.c32)
provided by udpcast and the main syslinux version.  This may or may not
cause problems, but definitely is unsupported.

It also breaks down if udpcast uses absolute paths or isn't prepared to
find its post-boot data files in a subdirectory.  But these would be a
problem with the pxechain approach as well.
-- 
Regards,
Feri.

--On Friday, July 23, 2010 01:23:30 PM +0200 Alain Knaff 
<syslinux at misc.lka.org.lu> wrote:
> Hello list,
>
> I am trying to prepare a USB disk with syslinux that is meant to be able
> to offer a choice among many different distributions. The goal is that I
> should be able to dump each distribution's CD contents into a separate
> subdirectory, and have a master menu that hands off to each
> distribution's subdirectory.
>
> A while back, when faced with a similar task on a PXE server, I came
> across pxechain.com which elegantly solves this issue. With pxechain.com
> I can say the following in my master pxelinux.cfg/default:
>
> default menu.c32
> prompt 0
> menu title LGL PXE boot menu
> timeout 100
>
> LABEL KubuntuNet
>         menu Kubuntu network install
>         kernel pxechain.com
>         append ::kubuntu904/netboot/pxelinux.0
>
> LABEL udpcast
>         menu label Udpcast
>         kernel pxechain.com
>         append ::udpcast/pxelinux.0
>
> This correctly hands off to the (unmodified) pxelinux.cfg/default's in
> the distribution's subdirectories. All KERNELs and initrds now use the
> subdirectory (kubuntu904, udpcast) as their current directory, rather
> than the original root directory.
>
> However, how can I achieve the same thing with syslinux (for USB keys)?
> There is MENU INCLUDE, but it doesn't change the current directory, so
> the submenu file must be edited to prepend the subdirectory to every
> kernel, initrd, display, function key, further submenues, ...
Consider putting each distro's files into a floppy image, and using MEMDISK 
to boot the second-level SYSLINUX from the virtual floppy.

-- Jeffrey T. Hutzelman (N3NHS) <jhutz+ at cmu.edu>
   Carnegie Mellon University - Pittsburgh, PA

On 07/23/2010 04:23 AM, Alain Knaff wrote:
> Hello list,
> 
> I am trying to prepare a USB disk with syslinux that is meant to be able
> to offer a choice among many different distributions. The goal is that I
> should be able to dump each distribution's CD contents into a separate
> subdirectory, and have a master menu that hands off to each
> distribution's subdirectory.
> 
> A while back, when faced with a similar task on a PXE server, I came
> across pxechain.com which elegantly solves this issue. With pxechain.com
> I can say the following in my master pxelinux.cfg/default:
> 
> default menu.c32
> prompt 0
> menu title LGL PXE boot menu
> timeout 100
> 
> LABEL KubuntuNet
>         menu Kubuntu network install
>         kernel pxechain.com
>         append ::kubuntu904/netboot/pxelinux.0
> 
> LABEL udpcast
>         menu label Udpcast
>         kernel pxechain.com
>         append ::udpcast/pxelinux.0
> 
> This correctly hands off to the (unmodified) pxelinux.cfg/default's in
> the distribution's subdirectories. All KERNELs and initrds now use the
> subdirectory (kubuntu904, udpcast) as their current directory, rather
> than the original root directory.
> 
> However, how can I achieve the same thing with syslinux (for USB keys)?
> There is MENU INCLUDE, but it doesn't change the current directory, so
> the submenu file must be edited to prepend the subdirectory to every
> kernel, initrd, display, function key, further submenues, ...
> 
CONFIG supports this in Syslinux 4:

LABEL subdir
	CONFIG subdir/syslinux.cfg
	APPEND subdir

	-hpa

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

On 07/25/2010 01:16 AM, H. Peter Anvin wrote:
> On 07/23/2010 04:23 AM, Alain Knaff wrote:
[...]
> CONFIG supports this in Syslinux 4:
> 
> LABEL subdir
> 	CONFIG subdir/syslinux.cfg
> 	APPEND subdir
> 
> 	-hpa
> 
Thanks,

Alain