Addressed feedback I received here and elsewhere on the previous patch. Please consider this alternative approach.

For additional context, here is the code from if_bridge.c this is based on:

case SIOCSIFMTU:
        if (ifr->ifr_mtu < 576) {
                error = EINVAL;
                break;
        }
        if (LIST_EMPTY(&sc->sc_iflist)) {
                sc->sc_ifp->if_mtu = ifr->ifr_mtu;
                break;
        }
        BRIDGE_LOCK(sc);
        LIST_FOREACH(bif, &sc->sc_iflist, bif_next) {
                if (bif->bif_ifp->if_mtu != ifr->ifr_mtu) {
                        log(LOG_NOTICE, "%s: invalid MTU: %u(%s)"
                            " != %d\n", sc->sc_ifp->if_xname,
                            bif->bif_ifp->if_mtu,
                            bif->bif_ifp->if_xname, ifr->ifr_mtu);
                        error = EINVAL;
                        break;
                }
        }
        if (!error)
                sc->sc_ifp->if_mtu = ifr->ifr_mtu;
        BRIDGE_UNLOCK(sc);
        break;

It was not obvious to me why the minimum MTU should be limited by IPv4 but I included it here erring on the side of caution.

The value seems to come from RFC791, quote:

Also, the manpage patch looks good to me.

Bumped the date in the man page.

You need to bump the .Dd at the beginning of the document to the date of the commit since this is a content change.

LGTM! I have spoke with Ryan to get a better scenario about this issue and here there is a reference for that: https://redmine.ixsystems.com/issues/25092

An update as regards the links issues. According to the Primer,

Also the second part has been completely revisited, to be more concise and more uniform to the original text.
Links to specific versions of the OS are still present. Please, refer to this previous comment for more details. How to fix this?

Thanks for the help kristof. I couldn't find the documentation to bound input of sysctl's but I definitely agree it's better to validate it on entry.

Updated with help from kristof to validate sysctl on change.

In D10600#337622, @bcr wrote:

So, you're saying the we need testers for this configuration before we put it in the handbook as official instructions?

So, you're saying the we need testers for this configuration before we put it in the handbook as official instructions?

Applied all the modifications suggested by @bcr . Thank you!
The line-breaking were a first attempt to handle too-long lines, your solution is far better. A couple of comments:

A few suggestions, mostly about line breaks with a few textual corrections.

I'd prefer the sysctl to reject values that are out of range.
What do you think about this: https://people.freebsd.org/~kp/patches/D14536.patch ?

Update sysctl to be based on decimal dscp value instead of toggle

ae's remarks

I think we can try to test this with wider auditory.

yeah I must've forgotten to do that sorry. Thanks!

style(9) issue - should not have trailing whitespace (tabs or spaces) at the end of the line
I will clean these up before commit

I added the pid in rS333489, as well as the pid for the LAN7801 (which Microchip sent me after the co-op term ended). I'll commit the driver with LAN7800 support only, then see if the 7801 "just works" or if we need additional changes.

A new version with a more concise text in the first part is available.

In D10600#323713, @wollman wrote:

Is it planned to address the client side (e.g., nss-pam-ldapd) or just the server?

Correction of the first part. The original text has been restored till the slapd.ldif example. The first section of slapd.ldif configuration has been significantly shortened, and many not necessary flaws have been deleted. If this is ok, the remainder can be modified following the same method.
The whole chapter

Is it planned to address the client side (e.g., nss-pam-ldapd) or just the server?

Looks good to me.

@shurd @sbruno might one of you commit this?

changed the file name, and variables. build passes.

I guess muggle is right out :)

After a brief IRC discussion it sounds like if_muge is the preferred option.
Aside, this exercise highlights that we need a man page for the new driver too.