Re: [Qemu-devel] [RFC 6/6] virtio-net: rss: Add bpf filter

[Daniel P . Berrangé]

On Tue, Sep 04, 2018 at 11:07:38AM +0800, Jason Wang wrote:
> 
> 
> On 2018年09月03日 19:54, Daniel P. Berrangé wrote:
> > > + *
> > > + * 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 file */
> > > +struct bpf_insn l3_l4_hash_insns[] = {
> > > +{0xbf , 0x6 , 0x1 , 0x0000 , 0x00000000},
> > > +{0x28 , 0x0 , 0x0 , 0x0000 , 0x0000000c},
> > > +{0xbf , 0x8 , 0x0 , 0x0000 , 0x00000000},
> > [snip]
> > 
> > > +};
> > This massive array is presumably an auto-generated content.
> > 
> > We shouldn't be storing this in GIT. We need to store the
> > original preferred source format, and providing makefile
> > rules to generate it.
> > 
> > 
> 
> 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 limitation.

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

Regards,
Daniel
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