Bug#960702: ethtool -m values change when output is redirected

From	"Yannis Aribaud" <bugs@d6bell.net>
Newsgroups	linux.debian.bugs.dist, linux.debian.kernel
Subject	Bug#960702: ethtool -m values change when output is redirected
Date	2020-05-15 19:40 +0200
Message-ID	<A6Mts-5oI-17@gated-at.bofh.it> (permalink)
References	<A6LQJ-4WH-5@gated-at.bofh.it> <A6LQJ-4WH-7@gated-at.bofh.it> <A6KrD-4d1-3@gated-at.bofh.it> <A6LQJ-4WH-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Cross-posted to 2 groups.

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15 mai 2020 18:40 "Bjørn Mork" <bjorn@mork.no> a écrit:

> "Yannis Aribaud" <bugs@d6bell.net> writes:
> 
> [...]
>
> To me it looks like you are just reading arbitrary numbers from the
> SFP+. Try replacing it and see if the results are more reliable.

I will try, but I am seeing the same behavior and similar values on 2 servers running the same hardware and the same software. The SFP+ modules model is commonly used on our equipements (servers, routers, switchs) and we never had such issues.

Values are clearly unreliable but not random at all. Values doesn't change between several runs of the command output redirected or not.

I mean values obviously change between redirected output and non redirected output runs, but not much between several runs redirected and neither between several runs non redirected.

Thus even if the values provided by the tranceivers are crazy, I see no reason seeing differences like those in values due to output redirect... I could not find any clue in the source code of ethtool, but I am no good developper at all.

Regards,

-- 
Yannis Aribaud

Thread

Bug#960702: ethtool -m values change when output is redirected "Yannis Aribaud" <bugs@d6bell.net> - 2020-05-15 17:30 +0200
  Bug#960702: ethtool -m values change when output is redirected Bjørn Mork <bjorn@mork.no> - 2020-05-15 19:00 +0200
    Bug#960702: ethtool -m values change when output is redirected "Yannis Aribaud" <bugs@d6bell.net> - 2020-05-15 19:40 +0200
  Bug#960702: ethtool -m values change when output is redirected Ben Hutchings <ben@decadent.org.uk> - 2020-05-16 01:40 +0200
    Bug#960702: ethtool -m values change when output is redirected "Yannis Aribaud" <bugs@d6bell.net> - 2020-05-17 17:00 +0200
      Bug#960702: ethtool -m values change when output is redirected Ben Hutchings <ben@decadent.org.uk> - 2020-05-17 18:10 +0200
        Bug#960702: ethtool -m values change when output is redirected "Yannis Aribaud" <bugs@d6bell.net> - 2020-05-18 12:10 +0200
  Processed: Re: Bug#960702: ethtool -m values change when output  is redirected "Debian Bug Tracking System" <owner@bugs.debian.org> - 2020-05-16 01:40 +0200
  Processed: Re: Bug#960702: ethtool -m values change when output  is redirected "Debian Bug Tracking System" <owner@bugs.debian.org> - 2020-05-17 18:10 +0200
  Bug#960702: [PATCH net] mlx4: Fix information leak on failure to read module EEPROM Ben Hutchings <ben@decadent.org.uk> - 2020-05-17 19:30 +0200
  Bug#960702: [PATCH net] mlx4: Fix information leak on failure to read module EEPROM Ben Hutchings <ben@decadent.org.uk> - 2020-05-18 20:30 +0200

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