[syslinux] DHCP option 93 for UEFI

[Ady]

This is slightly off-topic for the Syslinux mailing list, but I think 

it is still pertinent and it might be helpful anyway.

I am confused about some conflicting information regarding DHCP 
option 
93, Architecture Type.

The UEFI specification v.2.4 Errata B, Table 179, "PXE Tag 
Definitions 
for EFI", makes reference to a table in:
 
<http://www.ietf.org/assignments/dhcpv6-parameters/dhcpv6-parameters.x
ml#processor-architecture> 

which in turn makes reference (among others) to another table in:
 <http://tools.ietf.org/html/rfc4578#section-2.1> 

These two tables contain conflicting information:

RFC 4578      - DHCPv6
 7 EFI BC     -  7 x64 UEFI
 9 EFI x86-64 -  9 EBC

In addition, there is a PDF _from the UEFI Group_, 
 "IPv6 Remote Boot Requirements From UEFI Forum", IETF 72, year 2008, 


which correctly reproduces the RFC 4578 (no conflict), and adds:
 6 EFI IA32  <- used by many vendors for legacy boot of x64 machine
 7 EFI BC   <- used by many vendors for EFI x64 boot

So, I have some questions:

1_ Which Architecture Type value "should" correspond to 
   (U)EFI (x86_)x64?

2_ Isn't this conflicting information "messing" what vendors are 
   supposed to set/follow?

3_ Is there older (U)EFI hardware following one convention and newer 
   (U)EFI hardware following another?

4_ In practical terms, what would be an "adequate" way to solve this 
   matter in the DHCP configuration file for option 93, 
   Architecture Type?

5_ Can/should other options be used instead of option 93 for UEFI 
   clients (e.g. "Class Identifier", option 60)? 
   Is this a practical solution for every conflicting case?

6_ Since the DHCPv6 (RFC 5970) and UEFI specs claim "to be in parity" 

   with RFC 4578 and the PXE specs, is this some kind of typo in 
anyone 
   of the aforementioned documents?

TIA,
Ady.