Re: [edk2-devel] [PATCH v1] NetworkPkg/UefiPxeBcDxe: Fix PXE_BOOT_SERVERS usage in boot info parse flow

["Laszlo Ersek" <lersek@redhat.com>]

On 08/19/20 20:46, Michael Brown wrote:
> On 19/08/2020 19:13, Laszlo Ersek wrote:
>> I'm still undecided whether option#43 / tag#6 / bit#3 being clear means
>> we should *ignore* PXE_BOOT_SERVERS (tag#8), but I'm willing to defer to
>> you on that. So, I can give a cautious
>>
>> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>>
>> for this patch.
> 
> FWIW, iPXE's equivalent logic (based on a combination of what the PXE
> spec says and what the Intel reference PXE implementation actually does,
> which is not necessarily the same thing) is to *ignore* PXE_BOOT_SERVERS
> if a DHCP filename is available and option 43 tag 6 bit 3 is *set*.

Sorry, I expressed my concern incorrectly (I think I was tripped up by
the typo in Maciej's commit message).

It's about bit#2 in PXE_DISCOVERY_CONTROL.

The question is whether bit#2 is *equivalent* to adhering to
PXE_BOOT_SERVERS ("if, and only if").

When bit#2 is set, the spec says we must. OK.

When bit#2 is clear, the spec doesn't say anything. So two
interpretations are possible, "we still may consider PXE_BOOT_SERVERS",
and "we must not consider PXE_BOOT_SERVERS".

Anyway -- I'm sending this just to explain my earlier email. My main
point remains:

http://mid.mail-archive.com/11640b08-6f42-e4d8-356d-91d4bdf86c2c@redhat.com

(alt link: https://edk2.groups.io/g/devel/message/64530)

Thanks
Laszlo