[syslinux] Updated status on UEFI compliant version of the pxechn-module

[Gene Cumm]

On Tue, Mar 15, 2016 at 9:32 AM, Jan Frode Jæger
<jan.frode.jaeger at ntnu.no> wrote:
> Hi,
>
> Ok, when can we then anticipate pxe-chaining to be possible with syslinux under the UEFI architecture? Are there any plans to implement both correct interfacing to UEFI as well as the issue of arbitrary UEFI images? Haven't tried to read the UEFI-specification as it is sub 3000-pages long, so I am a bit in the dark as to the changes in architecture from BIOS to UEFI. It has been "fun" enough to read the PXE 2.1-specification and see how it manifests its horror in actual PXE ROM implementations and its impact on the PXE boot-process on various hardware (Microsoft and others blame unworking features of the DHCP options, but in actuality the fault seems to lie the rather vague specification of PXE 2.1 as far as I can see).

Without trying to figure out where data is stored or the possibility
of calls to manipulate the data, I can't speak for the possibility of
implementing anything that manipulates the options like pxechn.c32 for
UEFI.  I'd like to get UEFI chaining working first.

The shear length comparison speaks a lot for the differences.  Yes,
I've read through most of the PXE spec as it relates to the boot
process.  As bad as you think PXE is, consider how UEFI has been a
moving target in some respects.

What do you expect to PXE chainload?  If you could provide details on
what you hope to achieve, someone might be able to offer a suggestion
or workaround.

> I just compiled up the 6.04-prerelease and can see that the pxechn-module has been removed from the two efi-trees. As a sidenote: the NEWS-file in the 6.04-prerelease is missing information about changes introduced in it (seems to be the file from 6.03).

NEWS has NOT been updated yet.

> As another sidenote and possible separate thread: since I couldn't get UEFI to boot pxelinux 6.03 properly before I saw your dhcp options fix (vendor encapsulated options), I implemented a simple PXE boot server ack-packet UDP server in perl (the PXE client basically tries to perform a PXE boot server discovery procedure). Works like a charm without the dhcp options under all the Intel Boot Agent versions I tried - only need to set the mtftp-server address as per recommendations in the PXE 2.1 spec. Is there any interest in me publishing this boot server ack-packet script for others to use? Microsoft and others want us to drop DHCP options and instead implement iphelpers in the router (if clients and servers are on separate subnets), but shouldn't be necessary as far as I can see. The origin of all this mess is again the PXE specification in my opinion...

Intel Boot Agent?  Really?  I've NEVER seen mention of "Intel Boot
Agent" on UEFI.

I'd certainly be interested in this Perl script.

-- 
-Gene

> ________________________________________
> From: Gene Cumm <gene.cumm at gmail.com>
> Sent: Tuesday, March 15, 2016 13:42
> To: Jan Frode Jæger
> Cc: syslinux at zytor.com
> Subject: Re: [syslinux] Updated status on UEFI compliant version of the pxechn-module
>
> On Tue, Mar 15, 2016 at 3:51 AM, Jan Frode Jæger <syslinux at zytor.com> wrote:
>> Hi,
>>
>>
>> I have browsed through your syslinux archives and see that the issue of an UEFI compliant version of the pxechn-module has come up several times:
>>
>>
>> http://www.syslinux.org/archives/2014-August/022611.html
>>
>> http://www.syslinux.org/archives/2015-March/023320.html
>>
>> http://www.syslinux.org/archives/2015-September/024231.html
>>
>>
>> Now the issue as I understand it is that the original pxechn-module has been written to interface with legacy BIOS and not UEFI. It also seems that Patricks update as of March 2015 gave positive indications that a general fix for com32-modules were possible.
>>
>>
>> It would have been nice to receive some update on both com32-module compliance for the UEFI architecture as well as for the pxechn-module in specific. We have a setup at my workplace that are dependant upon this working and right now the only solution is to use legacy BIOS PXE-boot.
>>
>>
>> Is there any fix for this in the recently mentioned 6.04 pre-release (soon to become release?)?
>
> No, I removed all modules with BIOSisms from UEFI builds like pxechn.c32.
>
> More importantly, Syslinux can't load arbitrary UEFI images yet.
>
> --
> -Gene