Re: [PATCH] net: Bring up all interfaces before going interactive

[Trent Piepho <trent.piepho@igorinstitute.com>]

On Tue, Sep 20, 2022 at 12:41 AM Sascha Hauer <s.hauer@pengutronix.de> wrote:
> On Mon, Sep 19, 2022 at 10:20:53AM -0700, Trent Piepho wrote:
> > On Fri, Sep 16, 2022 at 6:16 AM Sascha Hauer <s.hauer@pengutronix.de> wrote:
> > >
> > > We could make the user experience even a bit better by doing this call
> > > before waiting for the autoboot timeout which then speeds up netboot a
> > > bit.
> >
> > The Linux phy driver almost invariably does not bother to avoid
> > resetting the network phy when not necessary.  So if network
> > auto-negotiation is started in barebox, it will be reset and then
> > restarted shortly after in Linux.  The link auto-negotiation impacts
> > the LAN's spanning tree if that is in use.
> >
> > So there is a drawback, besides the small added boot time to
> > initialize the network hardware, to adding an unneeded network restart
> > in Barebox in the case where interactive mode is not entered and
> > network boot is not used.
>
> So is this a vote to only do the autonegotiaton when going interactive
> in barebox, or a vote to do autonegotiation only when the network is
> being used in barebox?

I would vote to only do it when going interactive.

It also seems reasonable to bring the network up quickly when network
booting, but I think determining if the system will network boot,
before actually trying to boot, is probably unreasonably difficult to
do.