[Dnsmasq-discuss] proxyDHCP + EFI PXE

[Simon Kelley]

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On 14/03/15 22:27, Steve Wescott wrote:
> This is due to Dnsmasq's use of DHCP Option 43. Many (most?) UEFI 
> implementations do not seem to handle this the same as bios
> systems. While I have not seen any definitive answers as to what
> has changed, there are many complaints about this on various
> forums. Maybe changes were made to accommodate pxe over ipv6? Just
> a guess.

I think this is a useful observation. Greg has sent me several
wireshark traces of successful boots using other systems, and none of
them use the PXE menu system, encapsulated in option 43.
> 
> Some examples:
> 
> "Some UEFI targets are not able to correctly process option 43. For
> those targets it is necessary to set option 66 and 67." [1] "UEFI
> devices are not correctly respecting the PXE Boot Menu options"
> [2] "the above works if dnsmasq does not act as a DHCP proxy. For
> some reason the EFI firmware does not handle that well" [3]
> 
> Since most large companies are presumably using a commercial
> solution or just straight dhcp options for pxe boot, efi support
> for Proxy DHCP has not trickled down to any open source projects
> that I am aware of. I would expect this to become an issue in the
> near future, as many new systems are EFI only and do not include a
> bios compatibility support module.
> 
> I would love to see this get fixed in Dnsmasq, but I would expect
> it would require some significant changes to how it handles Proxy
> DHCP.

I'm thinking about it. It may be as simple as decoupling control of
the pxe subsystem from the existance of pxe-prompt and pxe-service
configuration options.

The Intel PXE 2.1 spec document must get some sort of "most useless
and confused specification" award.

Cheers,

Simon.

> 
> [1] 
> http://www-01.ibm.com/support/knowledgecenter/SS3HLM_7.1.1.14/com.ibm.tivoli.tpm.osd.doc/install/cosd_idhcp.htm
>
> 
[2] https://community.landesk.com/support/message/90065#sthash.ctWAPCAS.dpuf
> [3]
> http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2014q1/008182.html
>
> 
Another interesting example: http://firmware.intel.com/messages/331
> 
> On Feb 14, 2015, at 06:04, Greg C <icypoint at outlook.com> wrote:
> 
>> Has anybody been able to pxeboot an EFI system using Dnsmasq in
>> proxyDHCP mode? Every machine I have tried fails to boot (mostly
>> newer Dells with Intel cards).
>> 
>> The relevant lines from from my config file are here: 
>> pxe-service=x86-64_EFI,"Loading...",snponly 
>> dhcp-range=192.168.0.0,proxy,255.255.0.0
>> 
>> Watching the traffic with wireshark I can see the proxy response
>> get sent containing my 'menu' encapsulated in option 43 with the
>> correct boot file name. Still, the client never seems acknowledge
>> the boot info, either by showing an error or attempting to boot.
>> It just times out after ~60 seconds and boots to the next device.
>> If I reboot using 'Legacy PXE', everything works perfectly (I
>> have a line for x86PC as well). If I switch from proxy to full
>> DHCP I can boot in EFI mode without issue. I am running Dnsmasq
>> version 2.71 on Ubuntu if that matters. Am I doing something
>> wrong, or does proxyDHCP not work with EFI systems yet? These
>> same machines can boot to Windows Deployment Services in
>> proxyDHCP mode, so I am sure EFI PXE is capable of booting this
>> way.
>> 
>> Thanks.
> 
> 
> 
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