Date: Thu, 11 Dec 2014 14:47:52 -0800 From: Eric Joyner <erj@erj.cc> To: Adrian Chadd <adrian@freebsd.org>, "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Cc: "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org>, Jack F Vogel <jfvogel@gmail.com>, Eric Joyner <erj@erj.cc>, Rui Paulo <rpaulo@me.com> Subject: Re: Adding new media types to if_media.h Message-ID: <CA%2Bb0zg-Q%2Br7nfzJJt8BEwvPdOD2SFp1GGKp-G_JmUCt16XKRUQ@mail.gmail.com> In-Reply-To: <CAJ-Vmok9eifN3=3eb8w-VJdfnKY5Qcgu1cZjpi3B8=pYnjsQLQ@mail.gmail.com> References: <CA%2Bb0zg80VPn%2BXLjQ5HZxLqsM-%2Bev65g8AYDpGfQD=Gruv-LPJg@mail.gmail.com> <1AA55540-AADD-45CB-BC93-E2F81258B1F1@me.com> <CAJ-Vmok9eifN3=3eb8w-VJdfnKY5Qcgu1cZjpi3B8=pYnjsQLQ@mail.gmail.com>
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Any other thoughts, or should I start looking at seeing what I can take copy from net80211? Also adding -net, since this is pretty relevant. On Tue, Dec 9, 2014 at 10:40 AM, Adrian Chadd <adrian@freebsd.org> wrote: > > On 9 December 2014 at 07:27, Rui Paulo <rpaulo@me.com> wrote: > > On Dec 9, 2014, at 01:05, Eric Joyner <erj@erj.cc> wrote: > >> > >> This is a continuation of a discussion from off the list: > >> > >> ixgbe needs to support devices with media types that aren't in > if_media.h; > >> for now those are 10GBaseKR, 10GBaseKX4, and 1000baseKX. Immediately, > we're > >> running into the issue that there is no room for all of these types > under > >> the IFM_ETHER category; there's only room for two more (and per John > >> Baldwin, only one more if one of those two unused types is to be used > for a > >> reserved type). Long term, there are going to be tons of media types for > >> future ethernet speeds like 25G, 50G, 100G, and etc, and ixl already > >> supports media types that aren't in if_media.h, either. > >> > >> So, something needs to change. Does anyone have any thoughts on what > should > >> happen? I've thought of a few things, but I don't have an adequate > grasp of > >> what the pros/cons of each are: > >> > >> 1. Add a new media category (like IFM_ETHER) and change kernel code to > >> treat it like the existing IFM_ETHER. This creates ~28 new media types > we > >> can use, but it may just be delaying the inevitable for a short time. > >> > >> 2. Extend media value from 32-bits to 64-bits. I don't have a good idea > of > >> what the consequences are of this on architectures that aren't amd64. > >> > >> 3. (Initially suggested by Adrian) would be to create a new media type > >> struct (instead of using an int value) or adding an extra value to the > >> existing ifmedia/ifmedia_entry struct for this. This sounds like the > best > >> solution to me, but I don't know how much effort it would take to > implement > >> -- does ifconfig need a lot of changing to handle this? > > > > ifconfig is a macro-intensive application, so maybe it's not that much > work. > > > >> Thoughts? Any previous discussions worth looking at? > > > > Hmm, it looks like you're limited in the number of bits because of how > the word was laid out. We can't simple remove token ring and get more bits > for ethernet... We could create another IFM_40GETHERNET type to replace > token ring but that would be ugly (the IFM_TYPE() macro could handle this > idiosyncrasy). > > > > I think if_media should probably be a structure with unions to store the > subtypes. net80211 has the same problem with MCS rates and we ended up > storing them outside if_media because of this. > > I think solving this like how it's done in net80211 (ie, with an > external structure that represents the media type details for a given > media) is the right thing to do. > > Otherwise it'll be a path to madness in the future. > > The net80211 side of things is mostly extensible and I'm going to > (eventually) end up using it for the 11ac rates that have shown up. I > couldn't do that whilst trying to cram it into the existing ifmedia > variable. > > > -adrian >
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