Date: Wed, 5 Sep 2018 17:42:06 -0700 From: John-Mark Gurney <jmg@funkthat.com> To: Marko Zec <zec@fer.hr> 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: <20180906004206.GB75530@funkthat.com> In-Reply-To: <20180905124730.0f266c37@x23> 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>
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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? Because if you add -DVIMAGE to the Makefile, you'll now break people who have kernels w/o VIMAGE.. And the only reason to build netmap module manually is because it's not hooked up. > > Il giorno mer 5 set 2018 alle ore 10:44 Marko Zec <zec@fer.hr> ha > > scritto: > > > > > On Tue, 4 Sep 2018 20:18:29 +0200 > > > Vincenzo Maffione <v.maffione@gmail.com> wrote: > > > > > > > Hi, > > > > I don't think the panic depends on the architecture. Also, it > > > > does not depend on using emulated mode or not. > > > > We have seen this happening on x86_64 on FreeBSD 12 head. > > > > > > > > As John-Mark says, kdloading netmap.ko is not enough. You need to > > > > open a netmap port corresponding > > > > to any network interface, e.g. > > > > # pkt-gen -i eth0 > > > > because this will trigger ifunit_ref() in the kernel (netmap > > > > tries to grab the interface called "eth0"). > > > > The ifunit_ref() panics and we still need to figure out why. > > > > > > After more carefully rereading jmg's original report, on amd64 I > > > reproduced exactly the same panic he reported on arm64, the summary > > > follows: > > > > > > - the problem can be observed as VNET related, and can be triggered > > > only on kernels built with "options VIMAGE" but without "device > > > netmap". > > > > > > - netmap.ko built using make buildkernel works fine. > > > > > > - netmap.ko built separately (cd sys/modules/netmap; make) panics > > > on a first reference to vale interface, such as "tcpdump -ni > > > vale1:a" > > > > > > - the problem is that the separately built module is compiled > > > without "options VIMAGE", and as such does not set curvnet prior to > > > calling into network stack functions, therefore we have a null > > > pointer dereference in ifunit_ref() and voila... > > > > > > - hence, there's nothing to fix in the netmap code, and there's > > > nothing to fix in the network stack either related to this > > > particular problem, but rather we need a general mechanism which > > > would prevent kldloading non-VNETized .ko modules into a VNETized > > > kernel. I have no idea how to approach this, besides adding bz@ to > > > the cc: list, perhaps he could chime in with some thoughts? -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."
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