Syslinux - Jun 2014 - Chainload pxelinux from pxelinux and pass parameters or change root dir?

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).

> 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.

On 06/18/2014 07:39 AM, Ady wrote:
> 
> 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?
> 
Anything that can be used as a filename.
> 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?
No.  The CONFIG directive is nothing special in this aspect.  It just
part of a filename.

lpxelinux.0 supports tftp, http, and ftp URLs at this point; if
gPXE/iPXE is used other methods may be available as well.

	-hpa