Date: Thu, 6 Sep 2018 08:35:35 +0200 From: Marko Zec <zec@fer.hr> To: John-Mark Gurney <jmg@funkthat.com> Cc: Vincenzo Maffione <v.maffione@gmail.com>, <bz@freebsd.org>, Luigi Rizzo <rizzo@iet.unipi.it>, "freebsd-net@freebsd.org" <net@freebsd.org> Subject: Re: vale and netmap module questions Message-ID: <20180906083535.36ac39ce@x23> In-Reply-To: <20180906004206.GB75530@funkthat.com> References: <20180901014953.GV45503@funkthat.com> <CA%2B_eA9gH_uzxV_YLBH1XdM-ygPUxXzD_W9_b45jTmeY-t0bQKg@mail.gmail.com> <20180901211123.GZ45503@funkthat.com> <20180904164303.68c43b6e@x23> <20180904162815.GA75530@funkthat.com> <CA%2B_eA9jp2rB0GjojNrbWuQJ3fChpF6U5KPOX-DvEzJDVzOSP4w@mail.gmail.com> <20180905104433.08ad13b8@x23> <CA%2B_eA9gxCrJXVFaooD4x491Ksff5=gomwfn0=E0X0_iuupuBHg@mail.gmail.com> <20180905124730.0f266c37@x23> <20180906004206.GB75530@funkthat.com>
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On Wed, 5 Sep 2018 17:42:06 -0700 John-Mark Gurney <jmg@funkthat.com> wrote: > Marko Zec wrote this message on Wed, Sep 05, 2018 at 12:47 +0200: > > On Wed, 5 Sep 2018 12:36:38 +0200 > > Vincenzo Maffione <v.maffione@gmail.com> wrote: > > > > > Hi Marko, > > > Thanks a lot for identifying the problem. > > > If I understand correctly, simply adding -D VIMAGE here > > > https://github.com/luigirizzo/netmap/blob/master/sys/modules/netmap/Makefile#L11 > > > would at least mitigate the issue. > > > If you think I'm right I'll just add it. > > > > Right, go for it... > > Why not just hook up netmap to the build? I have no idea why it is on by default only on amd64... Perhaps due to the lack of adopters / testers on other platforms? Perhaps the code has some assumptions re. memory coherence model, or unaligned accesses, which hold the water on amd64 but not necessarily elsewhere? > Because if you add -DVIMAGE to the Makefile, you'll now break people > who have kernels w/o VIMAGE.. No, and this is certifiable. At least in this particular case, we have only two macro instances which set / restore curvnet prior to calling into the network stack. If the network stack is of the non-VNET kind, and thus doesn't care about curvnet, that won't do any harm. > And the only reason to build netmap module manually is because it's not hooked up. There's still a reason to retain the possibility to build netmap as module, as this speeds up the development cycles for netmap-internal hackers / experimenters. But beyond that, running netmap without native support in device drivers is pretty much pointless.
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