Re: [PATCH v13 net-next 07/11] bpf: verifier (add ability to receive verification log)

From: Alexei Starovoitov
Date: Fri Sep 19 2014 - 17:04:56 EST

On Thu, Sep 18, 2014 at 10:28 AM, Daniel Borkmann <dborkman@xxxxxxxxxx> wrote:
> On 09/18/2014 05:24 PM, Alexei Starovoitov wrote:
> ...
>> solve or not. If we decide to solve it, we need to have
>> a plan to solve it all the way. Partial fix for size of bpf_attr
>> is not a plan. It's something that is not addressing the problem
>> completely. Little bit of help is not useful for userspace. It
>> would need to deal with new types, verifier differences and
>> other things that I mentioned earlier.
> Hm, I don't think it would be a strict requirement to solve it
> all the way, and I think that perf_event_open() with perf_copy_attr()
> is not trying to do so either. It, however, is trying on a ``best
> effort basis'' to still load something if new features are unused
> by the binary (I guess you saw the comment in perf_copy_attr()).
> Iff, e.g. due to new types we fail at the verifier stage, sure,
> that's life since we only have backwards-compatible guarantee,
> but in case we tried to use features we support, we're still able
> to load the eBPF program while right now, we're rejecting it right
> up-front. That's just my $0.02 ...


the 'changes requested' status means that you want me to
address this forward compatibility now instead of later?
Or something else?
I don't want to second guess, respin and spam people
unnecessary. In this case I don't think Daniel is insisting
on doing it in this patch set. The things discussed above
are not urgent. Unless I'm missing something.
Please clarify.

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