[syslinux] Chainload pxelinux from pxelinux and pass parameters or change root dir?

[Ady]

> On 06/16/2014 07:12 PM, H. Peter Anvin wrote:
> > On 06/16/2014 02:57 PM, Alexander Perlis wrote:
> >> Here's what I mean by 'chainloading to install an automatic http prefix':
> >
> > The other option is to use a very small default configuration file
> > containing only:
> >
> > default reload
> > label reload
> >     config http://...path to real config file .../  http://...new path
> > prefix.../
> 
> This works great! I'm now DHCP-invoking lpxelinux.0 and then using this 
> CONFIG approach to change the global prefix to "http://my.ip/".
> 
> This is more efficient than using pxechn.c32, if the only goal is to 
> reload the same NBP on the same server but simply with a different 
> global prefix.
> 
> Also glad to have learned about pxechn.c32 for when we need to switch to 
> a *different* NBP (e.g., a different version of syslinux).
> _______________________________________________
 
Is there any documentation / email / examples / article / commit / 
reference of any kind about how to use the CONFIG directive with 
{l,g,}pxelinux.0 so to change the "working directory" (or its 
equivalent)?

If there is no such reference, other than the typical
 CONFIG </path/to/cfg/file/><configfile.cfg> 
 APPEND </path/to/new/base/dir> 

what are the possible methods / formats / protocols that can be used 
(and how) with the CONFIG directive?

Is there any syntax or feature for the CONFIG directive that is 
available for one protocol or filesystem but that is not allowed / 
available for others?

TIA,
Ady.