netdev - Re: [PATCH 2/2] [RFC] packet: experimental support for 64-bit timestamps

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Message-ID: <20171127165945.GC1971@nanopsycho.orion>
Date:   Mon, 27 Nov 2017 17:59:45 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     "David S. Miller" <davem@...emloft.net>, y2038@...ts.linaro.org,
        Shuah Khan <shuah@...nel.org>,
        Willem de Bruijn <willemb@...gle.com>,
        Mike Maloney <maloney@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        "Rosen, Rami" <rami.rosen@...el.com>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        "Reshetova, Elena" <elena.reshetova@...el.com>,
        Sowmini Varadhan <sowmini.varadhan@...cle.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Subject: Re: [PATCH 2/2] [RFC] packet: experimental support for 64-bit
 timestamps

Mon, Nov 27, 2017 at 05:19:25PM CET, arnd@...db.de wrote:
>I tried to figure out what it would take to do a version 4 mmap packet
>socket interface to completely avoid the y2106 overflow problem. This is
>what I came up with, reusing most of the v3 code, except for the parts
>where we access the timestamps.
>
>For kselftest, I'm adding support for testing v4 in addition to v1-v3,
>but the test currently does not look at the timestamps, so it won't
>check that the timestamp format actually works as intended, only that
>I didn't break the parts that worked in the v3 selftest.
>
>Overall, this is more of a mess than I expected, so it's probably not
>worth doing a v4 format just for the timestamp, but the patch can serve
>as a reference for anyone that needs a new format for other reasons and
>fixes this along with the other changes.
>
>Signed-off-by: Arnd Bergmann <arnd@...db.de>
>---

[...]


>@@ -250,7 +269,8 @@ struct tpacket_block_desc {
> enum tpacket_versions {
> 	TPACKET_V1,
> 	TPACKET_V2,
>-	TPACKET_V3
>+	TPACKET_V3,
>+	TPACKET_V4,

I wonder with how many versions are we going to eventually end up with :O