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Date:      Wed, 4 Nov 2020 13:39:09 +0100
From:      Kurt Jaeger <pi@freebsd.org>
To:        John F Carr <jfc@mit.edu>
Cc:        =?iso-8859-1?Q?S=F8ren?= Schmidt <soren.schmidt@gmail.com>, "freebsd-arm@freebsd.org" <arm@freebsd.org>
Subject:   Re: if_mvneta rx/tx byte counts wrong
Message-ID:  <20201104123909.GF53210@home.opsec.eu>
In-Reply-To: <858E0BCD-C4E9-4997-A982-3C19DF21D161@exchange.mit.edu>
References:  <57104A54-AC82-4102-A637-116BF8D2E17D@gmail.com> <858E0BCD-C4E9-4997-A982-3C19DF21D161@exchange.mit.edu>

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Hi!

> If you view in hex,
> 
> $ printf '%x %x %x\n' 443193380410133 3813930959736 274877907008
> 1931500019315 37800000378 4000000040
> 
> you see a 32 bit value duplicated into both halves of a 64 bit value.

Ah. I think Juniper switches have the same problem -- I heard
that this is a timing/atomicity problem of writing 64bit values
on arm32.

-- 
pi@opsec.eu            +49 171 3101372                    Now what ?



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