netdev - Re: [PATCH RFC 1/3] xdp: Infrastructure to generalize XDP

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Date:   Sun, 25 Sep 2016 07:32:42 -0400
From:   Jamal Hadi Salim <jhs@...atatu.com>
To:     Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     Tom Herbert <tom@...bertland.com>, davem@...emloft.net,
        netdev@...r.kernel.org, kernel-team@...com, tariqt@...lanox.com,
        bblanco@...mgrid.com, alexei.starovoitov@...il.com,
        eric.dumazet@...il.com, Thomas Graf <tgraf@...g.ch>
Subject: Re: [PATCH RFC 1/3] xdp: Infrastructure to generalize XDP

On 16-09-23 09:00 AM, Jesper Dangaard Brouer wrote:
> On Fri, 23 Sep 2016 07:13:30 -0400
> Jamal Hadi Salim <jhs@...atatu.com> wrote:
>

[..]

>> Tom,
>> perused the thread and it seems you are serious ;->
>> Are we heading towards Frankenstein Avenue?
>> The whole point behind letting in XDP is so that _small programs_
>> can be written to do some quick thing. eBPF 4K program limit was
>> touted as the check and bound. eBPF sounded fine.
>> This sounds like a huge contradiction.
>>
>> cheers,
>> jamal
>
> Hi Jamal,
>
> I don't understand why you think this is so controversial. The way I
> see it (after reading the thread): This is about allowing kernel
> components to _also_ use the XDP hook.
>

The initial push was XDP to support very small programs that did
very simple things fast (to be extreme: for example running a whole
network stack is a no-no). EBPF with the 4K program limit was pointed
as the limit.
What Tom is presenting is implying this constraint is now being
removed. Thats the controversy.

cheers,
jamal