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

[Frantisek Rysanek]

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 
reproduction.)

> 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 :-)

Frank