netdev - Re: [PATCH net-next 1/9] bpf: add BPF

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Message-ID: <598B7ED3.5030005@iogearbox.net>
Date:   Wed, 09 Aug 2017 23:29:55 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     David Miller <davem@...emloft.net>
CC:     ast@...com, holzheu@...ux.vnet.ibm.com,
        naveen.n.rao@...ux.vnet.ibm.com, jakub.kicinski@...ronome.com,
        netdev@...r.kernel.org
Subject: Re: [PATCH net-next 1/9] bpf: add BPF_J{LT,LE,SLT,SLE} instructions

On 08/09/2017 11:26 PM, David Miller wrote:
> From: Daniel Borkmann <daniel@...earbox.net>
> Date: Wed, 09 Aug 2017 22:32:34 +0200
>
>> For the case of cilium, we are not in control of the kernel, by
>> the way, we run a few probes that are small BPF insns snippets
>> that test the kernel for presence of certain features (e.g. helper,
>> verifier, maps) and enable/disable them accordingly later in the
>> code generation. On the user space side, we're indeed a bit more
>> flexible and have no such restriction.
>>
>> Plan is for LLVM as one of the frontends that generate byte code
>> (ply, for example, can probe the kernel directly for its code
>> generation) to have i) a target specific option to offer a
>> possibility to explicitly enable the extension by the user (as we
>> have with -m target specific extensions today for various cpu
>> insns), and ii) have the kernel check for presence of the extensions
>> and enable it transparently when the user selects more aggressive
>> options such as -march=native in a bpf target context, so we can
>> select the underlying features transparently. I should have made
>> that more clear earlier, sorry about that.
>
> I think this explanation needs to be in either your header posting
> or the commit message of patch #1.
>
> Thanks :)

Ok, sure, I'll do a v2 with that included. Thanks!