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Date: Tue, 4 Sep 2018 09:14:23 +0100
From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= <berrange@redhat.com>
Message-ID: <20180904081423.GA22349@redhat.com>
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References: <20180830142708.14311-1-sameeh@daynix.com>
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Subject: Re: [Qemu-devel] [RFC 6/6] virtio-net: rss: Add bpf filter
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To: Jason Wang <jasowang@redhat.com>
Cc: Sameeh Jubran <sameeh@daynix.com>, Yan Vugenfirer <yan@daynix.com>, qemu-devel@nongnu.org

On Tue, Sep 04, 2018 at 11:07:38AM +0800, Jason Wang wrote:
>=20
>=20
> On 2018=E5=B9=B409=E6=9C=8803=E6=97=A5 19:54, Daniel P. Berrang=C3=A9 w=
rote:
> > > + *
> > > + * This work is licensed under the terms of the GNU GPL, version 2=
 or later.
> > > + * See the COPYING file in the top-level directory.
> > > + *
> > > + */
> > > +
> > > +#include <linux/bpf.h>
> > > +
> > > +#ifndef BPF_RSS_INSNS
> > > +#define BPF_RSS_INSNS
> > > +
> > > +/* bpf_insn array matching l3_l4 section. see tap_bpf_program.c fi=
le */
> > > +struct bpf_insn l3_l4_hash_insns[] =3D {
> > > +{0xbf , 0x6 , 0x1 , 0x0000 , 0x00000000},
> > > +{0x28 , 0x0 , 0x0 , 0x0000 , 0x0000000c},
> > > +{0xbf , 0x8 , 0x0 , 0x0000 , 0x00000000},
> > [snip]
> >=20
> > > +};
> > This massive array is presumably an auto-generated content.
> >=20
> > We shouldn't be storing this in GIT. We need to store the
> > original preferred source format, and providing makefile
> > rules to generate it.
> >=20
> >=20
>=20
> This is possible. But it depends on eBPF toolchain (e.g recent version =
of
> LLVM) to work which is inflexible or impossible to make it work on some
> distributions. Providing compiled bytecode does not have such limitatio=
n.

Those distros can fix their toolchain if they wish to have the BPF featur=
e
enabled when building QEMU, just like they would for any other dependancy
that is needed by QEMU.

Regards,
Daniel
--=20
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