From: Arnd Bergmann <arnd@arndb.de>
To: andy.green@linaro.org
Cc: linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org,
patches@linaro.org, nicolas.pitre@linaro.org, x0132446@ti.com,
s-jan@ti.com, tony@atomide.com
Subject: Re: [RFC PATCH 1/2] OMAP2+: add cpu id register to MAC address helper
Date: Fri, 25 Mar 2011 14:24:46 +0100 [thread overview]
Message-ID: <201103251424.47141.arnd@arndb.de> (raw)
In-Reply-To: <4D8C85DB.6060001@linaro.org>
On Friday 25 March 2011, Andy Green wrote:
> Having a proper MAC from IEEE assigned for each interface is of course
> ideal.
>
> But even if that happened today though, on Panda there is no "board
> identity storage" to put the reserved MAC addresses in to bind it to the
> physical board. If you try to manage them on SD Card, you have the
> problem of dealing with correct MAC addresses needing putting there
> again every time it is nuked. So it doesn't in itself help in the Panda
> case.
What I meant is computing an official MAC address from the same input
data as you already do. Unfortunately that would mean having at most 24
bits available instead of the 44 or so bits you currently use, because
the upper half of the address then becomes fixed.
Also it would require
1. defining an new algorithm that computes the lower 24 bits from the
die ID in a way that minimises the chances of collision
2. Getting an official identifier for the upper half of the address
assigned to the OMAP3/OMAP4 CPUs
3. Documenting this method in the OMAP data sheets.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH 1/2] OMAP2+: add cpu id register to MAC address helper
Date: Fri, 25 Mar 2011 14:24:46 +0100 [thread overview]
Message-ID: <201103251424.47141.arnd@arndb.de> (raw)
In-Reply-To: <4D8C85DB.6060001@linaro.org>
On Friday 25 March 2011, Andy Green wrote:
> Having a proper MAC from IEEE assigned for each interface is of course
> ideal.
>
> But even if that happened today though, on Panda there is no "board
> identity storage" to put the reserved MAC addresses in to bind it to the
> physical board. If you try to manage them on SD Card, you have the
> problem of dealing with correct MAC addresses needing putting there
> again every time it is nuked. So it doesn't in itself help in the Panda
> case.
What I meant is computing an official MAC address from the same input
data as you already do. Unfortunately that would mean having at most 24
bits available instead of the 44 or so bits you currently use, because
the upper half of the address then becomes fixed.
Also it would require
1. defining an new algorithm that computes the lower 24 bits from the
die ID in a way that minimises the chances of collision
2. Getting an official identifier for the upper half of the address
assigned to the OMAP3/OMAP4 CPUs
3. Documenting this method in the OMAP data sheets.
Arnd
next prev parent reply other threads:[~2011-03-25 13:24 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-24 21:27 [RFC PATCH 0/2] OMAP2+: PANDA: Provide unique-ish MAC addresses for Ethernet and WLAN interfaces Andy Green
2011-03-24 21:27 ` Andy Green
2011-03-24 21:27 ` [RFC PATCH 1/2] OMAP2+: add cpu id register to MAC address helper Andy Green
2011-03-24 21:27 ` Andy Green
2011-03-25 11:49 ` Arnd Bergmann
2011-03-25 11:49 ` Arnd Bergmann
2011-03-25 12:08 ` Andy Green
2011-03-25 12:08 ` Andy Green
2011-03-25 13:24 ` Arnd Bergmann [this message]
2011-03-25 13:24 ` Arnd Bergmann
2011-03-25 13:34 ` Andy Green
2011-03-25 13:34 ` Andy Green
2011-03-25 14:50 ` Arnd Bergmann
2011-03-25 14:50 ` Arnd Bergmann
2011-03-25 15:00 ` Andy Green
2011-03-25 15:00 ` Andy Green
2011-03-24 21:27 ` [RFC PATCH 2/2] OMAP2+: PANDA: Fix up random or missing MAC addresses for eth0 and wlan0 Andy Green
2011-03-24 21:27 ` Andy Green
2011-03-25 7:39 ` Hema Kalliguddi
2011-03-25 7:39 ` Hema Kalliguddi
2011-03-25 20:13 ` Jason Kridner
2011-03-25 20:13 ` Jason Kridner
2011-03-25 20:20 ` Arnd Bergmann
2011-03-25 20:20 ` Arnd Bergmann
2011-03-25 20:23 ` Nicolas Pitre
2011-03-25 20:23 ` Nicolas Pitre
2011-03-28 12:54 ` Jason Kridner
2011-03-28 12:54 ` Jason Kridner
2011-03-25 20:30 ` Andy Green
2011-03-25 20:30 ` Andy Green
2011-03-25 11:39 ` Arnd Bergmann
2011-03-25 11:39 ` Arnd Bergmann
2012-06-28 14:18 ` [RFC PATCH 0/2] OMAP2+: PANDA: Provide unique-ish MAC addresses for Ethernet and WLAN interfaces Arnd Bergmann
2012-06-28 14:18 ` Arnd Bergmann
2012-06-28 14:45 ` Steven Rostedt
2012-06-28 14:45 ` Steven Rostedt
2012-06-28 14:49 ` "Andy Green (林安廸)"
2012-06-28 14:49 ` "Andy Green (林安廸)"
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