[syslinux] Suggested update to the Wiki page on PXElinux (UEFI-related stuff in ISC dhcpd.conf)

Frantisek Rysanek Frantisek.Rysanek at post.cz
Fri Nov 8 01:54:56 PST 2019

On 8 Nov 2019 at 0:42, Ady Ady via Syslinux wrote:

> [in response to my = Frank Rysanek's rantings a few hours earlier:]

> > if option architecture-type = 00:09 {
> >  filename "path/to/EFIx64/syslinux.efi";
> > }
> > if substring (option vendor-class-identifier, 15, 5) = "00007" {
> >  filename "pxelinux/6.git/efi64/syslinux.efi";
> > }
> > (plus the snippet on ignore-client-uids)

> The dhcpd.conf examples in the wiki page were modified from "nn:nn" to 
> "decimal" format by HPA in 2016 (quoting HPA: "UEFI - clean up 
> dhcpd.conf examples").

allright so this might be a matter of different versions of ISC dhcpd 
behaving slightly different through the ages...

> Please note that several other sites (e.g. the FOG wiki) also use 
> simple decimal notation for these types of examples. Whether the 
> decimal notation is actually invalid, or at least problematic, I don't 
> really know.
> If during the next few days there are no new emails objecting the 
> suggested change, I'll revert the dhcpd.conf examples in the PXELINUX 
> wiki page back to "nn:nn" format. Although feedback from GeneC and from 
> HPA regarding this matter would be particularly interesting, comments 
> from anyone are very much appreciated.
Obviously you guys have more experience with this throughout the 
decades of history. I only return to the dhcpd.conf now and then, at 
points isolated by years of "no change" in time.
I mean I definitely trust your judgement on all of this.
> Other than that simple change, I'd like to know what other changes you 
> are proposing, specifically.
No other changes at the moment. I've specifically tried to boil down 
the "integer literal value" thing to the minimum possible example.
(My favourite approach when trying to demonstrate problem 

> Alternative ways to do things can be welcomed. Please consider that 
> this wiki page is about PXELINUX (not about dhcpd.conf) and that these 
> are only examples, not complete docs about dhcpd.conf. 
Yes I understand that you prefer not to turn the PXElinux Wiki into a 
surrogate ISC dhcpd config reference :-)
That said, the PXElinux Wiki page appears to be a pretty central 
place where to document PXEboot-related peculiarities.
(That's why I dared to mention the ignore-client-uids DHCP option.
The related common omission in PXE oproms or rather DMI BIOS tables 
really hurts us a lot.)

Also, freelance PXE booting (as compared to turn-key end-to-end 
proprietary solutions by Microsoft, ACP Thinmanager and the like) 
tends to be one of the universal hot-spots of "creme de la creme" 
DHCP sorcery :-) Unfortunately there's no escaping complex 
configurations and ugly details... Or, would you suggest a rather 
more appropriate "hosting space" for complex boilerplate dhcpd.conf 
examples? ;-) 

I believe that even this mailing-list posting of mine is itself 
useful in that vein, as it gets archived at syslinux.org and indexed 
by Google...

> Perhaps a small, 
> partial snippet or phrase located in an adequate place within the page 
> might be enough. 
I see - like a surgical one-liner patch into the wiki page.

Unfortunately in this case I don't feel confident about what's right 
and what's possibly wrong. Hence my talkative handling of this case 
I'd prefer to leave the precise formulation to you maintainer guys...

> Sometimes, linking to other (trustworthy) resources, 
> and/or linking to an email in this Mailing List, might be better.
The trouble is that *the* canonical place for "all things PXE" to me 
has always been the PXElinux wiki :-) Random other people's blogs, or 
third-party derived project sites, to me are all less authoritative 
and possibly less durable. And all I can offer on my part is 
immediate personal experience with my particular setup...

Thanks for all your help and activity :-)


More information about the Syslinux mailing list