[syslinux] PXELinux CFG file problem

Dyks, Axel (XL) xl at xlsigned.net
Sun May 6 13:14:20 PDT 2007


H. Peter Anvin wrote:
> Dyks, Axel (XL) wrote:
>> So while "pxelinux[.0]" is loaded from "boot-server", "pxelinux" itself
>> is left without a valid ip-address (next-server) to continue from.
>>
>> I don't know, if it would be possible for "pxelinux" to derive "next-server"
>> from "boot-server", in case that "next-server" is empty.
>> But perhaps the "boot-server" information is no longer available when
>> "pxelinux" is executed, otherwise -- I guess -- hpa would have already
>> implemented this.
>>
> 
> Well, what one can do is to violate the protocol (which the PXE stack
> itself apparently does here) and so something like that... it might be
> the right thing to do. 

Well, after doing my analysis and also figuring out that the PXE stack
actually does the wrong thing, I doubt that "meaning well" is equal to
"doing well" in this case.
// I originally thought that there would be a technical problem instead
// of a protocol violation that prevents pxelinux from setting
// next-server to boot/dhcp-server ...

If the PXE stack -- propably "meaning well" -- wouldn't violate RFC2131,
nobody would see pxelinux failing to download the config files after
being downloaded by itself from the same TFTP server.

I currently can't think of a scenario in which a more "meaning well"
pxelinux would simply pass on the problem to a subsequent stage in the
boot process, but you'll never know ...

After all, the solution is simple. RTFM and add "next-server" to "dhcpd.conf".

:-) Axel




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