Date: Sun, 29 Jan 2012 14:44:13 +0200 From: Aleksandr Rybalko <ray@ddteam.net> To: Stefan Bethke <stb@lassitu.de> Cc: Juli Mallett <jmallett@FreeBSD.org>, FreeBSD Net <freebsd-net@freebsd.org>, Adrian Chadd <adrian@freebsd.org>, Aleksandr Rybalko <ray@freebsd.org>, FreeBSD-arch <freebsd-arch@freebsd.org> Subject: Re: Ethernet Switch Framework Message-ID: <20120129144413.a8045873.ray@ddteam.net> In-Reply-To: <045BA867-B83B-4C2E-AB4F-4D09E49B7F3D@lassitu.de> References: <20120120221319.ca8b631f.ray@freebsd.org> <30A45A1E-CA13-4AC8-86FB-F8E06301D1F6@lassitu.de> <20120122195130.360261ce.ray@freebsd.org> <CAJ-VmokTh2q0ZH=kwU6GzJm5Mr4k7geJiFsoX_A9hcLhMZNxsg@mail.gmail.com> <0E31FEC4-963D-4AC8-9AB7-EE6D6D7F86EE@lassitu.de> <CAJ-Vmo=GRKRf%2BYsFqNm9d_T3Tq583uV_pabMV6ozuaytSRLivg@mail.gmail.com> <20120129001251.7e4cfe83.ray@ddteam.net> <CACVs6=-U9rr7cpeJ%2BVUgP3Xq1yRB=Xk1GjuzEOuXiEUoqGFq_Q@mail.gmail.com> <045BA867-B83B-4C2E-AB4F-4D09E49B7F3D@lassitu.de>
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On Sun, 29 Jan 2012 13:26:00 +0100 Stefan Bethke <stb@lassitu.de> wrote: > Am 29.01.2012 um 00:00 schrieb Juli Mallett: > > > On Sat, Jan 28, 2012 at 14:12, Aleksandr Rybalko <ray@ddteam.net> > > wrote: > >> As I see from your patch, mdio/miiproxy require special bits in MAC > >> driver. When I design switch framework, I keeping in mind that > >> MAC drivers should be standard as possible > > > > I don't understand why this is desirable in practice. It's a nice > > theory, but it falls down when one thinks in depth about how > > Ethernet interfaces are used and administered vs. how switches are > > used and administered. What should media report? What should > > media changes do? What is link status? Do you show the > > CPU-to-switch port, or all switch ports? > > The main thrust here is to reuse the existing PHY code to be able to > configure the PHYs that are embedded in the switch chips. To confuse > things, one of these PHYs might be connected to the SoCs ethernet > interface via MII, GMII, etc. To confuse things further, these PHYs > are controlled by an MDIO bus that has it's master in the switch > chip, while the switch chip is a slave to the MDIO master in the > ethernet controller. > > The goal is to be able to configure the switch ports and set media on > one of them, for example. That code path could be entirely > independent from the ethernet infrastructure, if dev/miibus didn't > require if_media and hence a struct ifnet. This discussion is also > about how to deal with this entanglement. > > The MII connection between the ethernet controller and the switch > chip (usually referred to as the "CPU" port) is hard-coded and has no > media settings, so there's no question what if_media settings should > be presented on the interface. Most switches (AR8x16 for example) have configurable MII port, so you can choose to use MII/RMII/GMII/RGMII. If you decide to use MII media can not be higher than 100baseTX. So it is possible to use some auto-negotiation here. > > > are a lot of switches out there that don't look or act much like > > MII-driven PHYs, but which are connected over MDIO, as I've tried to > > stress before. I hope there will be as much separation between the > > MII work that is being done and the switch work that is being done > > as possible. I think anything else will prove rapidly-obsolete and > > perhaps even obstructive as soon as anyone seeks to add support for > > more switch chipsets to FreeBSD. > > > > I suppose the most likely reality, though, is that people simply > > won't add switch support to FreeBSD, and will administer them > > out-of-band from userland, using gross kernel shims. That is > > probably true whether any of the currently-outstanding work is > > committed or not, unfortunately :( I just hope we'll end up with > > something flexible enough, broad enough in applicability, narrow > > enough in requirements, etc., that we'll have feature-rich support > > for a few chipsets in tree that work in sufficiently-different > > manners that they can be models for other drivers in the future. > > Which is a valid approach from a vendor's viewpoint. The reason > we're talking is to try and make it easier to write a switch driver > for this framework than roll your own hack. :-) > > > Stefan > > -- > Stefan Bethke <stb@lassitu.de> Fon +49 151 14070811 > > > -- Aleksandr Rybalko <ray@ddteam.net>
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