Re: Legacy Linux kernel support

[Mario Rugiero via tcpdump-workers <tcpdump-workers () lists tcpdump org>]

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>
>
> From: Mario Rugiero <mrugiero () gmail com>
>
> Date: Tue, 22 Oct 2019 18:24:43 -0300
>
> El mar., 22 oct. 2019 a las 18:01, Guy Harris (<gharris () sonic net>) escribió:
> > If RHEL 6 matters, oldest longterm from kernel.org only doesn't work, because RHEL 6 runs 2.6.32, according to
> >
> >         https://access.redhat.com/articles/3078
> >
> > so if we're going to support only the oldest longterm maintenance kernel from kernel.org, we're not going to support 
> > RHEL 6 unless TPACKET_V3 has been back ported to the RHEL 6 kernel.
> >
> > If it's not backported, *and* we continue to use TPACKET_V2 for immediate mode, then RHEL 6 happens to still be 
> > supported to that extent.
> >
> > However, if we require any *other* mechanisms that aren't present in the RHEL 6 kernel, that means no RHEL 6 support.
> >
> > So I wouldn't claim RHEL 6 support solely on the basis of continued TPACKET_V2 support - don't rely on the side 
> > effect.
> Exactly. I'm against supporting it if it requires extra work. I don't
> think libpcap 1.10 is an absolute need in a scenario where you have to
> deal with RHEL 6, except possibly for security fixes, but those will
> have to be backported by Red Hat anyway.
>
> > Either that, or just change TPACKET_V3 to do that.
> Yes, that's what I was proposing.
>
> > Originally, TPACKET_V3 delivered wakeups in a bogus fashion:
> >
> > ...
> >
> > The code currently has the patch, and doesn't deliver empty blocks.
> I'll read these carefully later, but my take on it is that TPACKET_V3
> used to support our use case, so in principle a patch to restore it
> could be accepted.
> I find it unclear whether it is the ability of posting of empty blocks
> that would break use cases or its absence from the previous paragraph,
> but I guess I'll know after reading the mails.
>
> > It doesn't look as if you've sent anything to netdev yet about tpacket changes.
> I haven't, I wanted to discuss this here first.
>
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