[syslinux] Question about pxelinux and gpxelinux

[Sean Lv]

Dear Hpa and Jeffrey, thanks a lot for your kindly help and clarification. 

For the second question, I searched the google whole day without any luck. And I got the confirm from one of Microsoft engineer, MS DHCP server do not support forced-DHCP-option, like ISC DHCP.  Anyone has a non-official trick?   

I have an idea related to my 2nd question. Since gpxelinux.0 takes place of vendor-PXE stack, is there any way to force gpxe-PXE stack request the specified DHCP option? Then, I think MS DHCP could provide all options that gPXE client requested.  I guess it's related to re-compile gpxelinux.0, which is beyond my knowledge :)  


I tried to interrupt the gpxelinux.0 boot process by crtl+B, then I could manually set some parameters, such as boot file name, default gateway. If the manual work can be replaced by a configuration file? How to do it? For example, I should put a file named gpxe.conf in the same path with gpxelinux.0 on my tftp server.

Thanks in advanced.


-----Original Message-----
From: H. Peter Anvin [mailto:hpa at zytor.com] 
Sent: 2009年1月6日 0:49
To: For discussion of Syslinux and tftp-hpa
Subject: Re: [syslinux] Question about pxelinux and gpxelinux

Sean Lv wrote:
> 	1, after I read the document
> (http://edgyu.excess.org/ols/2008/H%20Peter%20Anvin%20-%20x86%20network%20bo
> oting%3a%20integrating%20gPXE%20and%20PXELINUX.pdf), I knew there are two
> major module in standard gPXE, PXE BC and UNDI. And I can understand why I
> need to produce different boot file for different NIC from
> http://rom-o-matic.net/, because the output file contain different UNDI.
> But I am really confused that why only one gpxelinux.0 (in syslinux 3.72
> package) could support all my NIC (at least 5) in my environment?  I guess
> the gpxelinux.0 use its own PXE BC and call vendor-UNDI from physical PXE
> ROM, as a result, gpxelinux.0 could support all my NIC(actually, it is
> supposed to support all NIC which have PXE ROM)  Am I right?

Yes.

> 	2, From rfc5071, pxelinux should request non-standard DHCP option
> from DHCP server, option 208-211. In my environment, I am using a Microsoft
> DHCP (Windows 2008). And I tried to set option 67 (boot file name) to
> publish pxelinux.0 & gpxelinux.0. I used wildpacket(just like Wireshark) to
> capture the packets btw PXE client and DHCP server. I could not see PXE
> client request option 208/209/210/211, although I am sure I configured these
> syslinux-DHCP option on my DHCP Server.  Why? I searched the google and
> official web site, all examples are using a linux-DHCP Server. I am not
> familiar with linux, and I am not sure if my issue is related to my
> Micrsoft-DHCP Server.  
> 
> 	It's appreciated if you can help me out. Thanks in advanced.
> 

PXELINUX doesn't request anything from the DHCP server, *because
PXELINUX isn't running yet*.  DHCP is done by PXE, so you have to
configure your DHCP server to send these options without having had them
requested.  This is also mentioned in RFC 5071 (fifth paragraph of
section 1.)

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.