In my point of view I would like to use this flag in /etc/make.conf instead of patching local src. Having this flag allow users to use it no only for me. It's only a proposal, so the end of this story only up to you.

It's the only one from pxeloader. I can safety remove the same from iPXE and in summary, during boot chain I have less a half of DHCP request in network. Let's say grain by grain...

small cleanup

https://reviews.freebsd.org/D10854

tftpfs it's not bad, but you don't know what ipxe will do in the next commit. The problem is that we want to think about all.

In D10603#223305, @tsoome wrote:

In D10603#223301, @bapt wrote:

We need to find a better mechanism, as this break usage where rootpath /something was before this patch expecting NFS to be located on the same serveur as the tftp server. This is now broken (it is used quite a lot apparently)

Which means we are back at the beginning; we can not use the initial pxe ack, we need to build the request asking for both tftp and nfs, and select the method based on response.

Continuation in D10603

And the last one possible solution:

@tsoome
I based on the Intel's PXE Specification and there 66 exists.

@rgrimes
Please try to boot CURRENT over tftp protocol and without any third part software like iPXE.

Until I go forward with your comments about the code I want to highlight it's not possible to support option 150, because we have to ask DHCP server for this option. PXE client (I mean network card firmware) never asks about option 150. I can't see any chance to use this non standard option but revert r314948 and always do DHCP request for everything. The second option is doing DHCP request in #ifdef LOADER_TFTP_SUPPORT directive, what is something bad too, because we want to have one universal loader for both (NFS and TFTP) protocols. The third option is to force DHCP request in ifdef directive when somebody really wants to do this. And the last one option - to leave support for option 150, because it has never appear in the documentation. I can't see any really good solution, now your move to comment.

@asomers
this change exactly provides compatibility with PXE standard, because in the PXE specification option 150 doesn't exist, but 66 does.
netproto variable and option 150 appears in r305125. Documentation and relnotes should be updated, but not by changing, because this part of loader never appers there (maybe I only can't find it).

oshogbo's comments fixed and some new improvements

It's should enough for backwards compatibility.

Tested on:

In D4689#98951, @nwhitehorn wrote:

The use case when installing multiuser is not that uncommon and is something that needs to continue working. One of two things needs to happen here before being committed:
(a) it needs to use only those ZFS filesystems previously mounted
(b) the zfsboot script should use the ZFS support in partedit, which already works with umount