From: Florian Fainelli <florian@openwrt.org>
To: Michael Buesch <mb@bu3sch.de>
Subject: Re: [PATCH RFC] ssb: Generic SPROM override for devices without SPROM
Date: Fri, 20 Nov 2009 15:16:09 +0100
Cc: bcm43xx-dev@lists.berlios.de,
	Larry Finger <Larry.Finger@lwfinger.net>,
	"linux-wireless" <linux-wireless@vger.kernel.org>
References: <200911201212.19588.mb@bu3sch.de> <4B06A233.2070708@lwfinger.net> <200911201511.11042.mb@bu3sch.de>
In-Reply-To: <200911201511.11042.mb@bu3sch.de>
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On Friday 20 November 2009 15:11:09 Michael Buesch wrote:
> On Friday 20 November 2009 15:05:39 Larry Finger wrote:
> > On 11/20/2009 05:12 AM, Michael Buesch wrote:
> > > This patch adds a generic mechanism for overriding the SPROM mechanism
> > > on devices without SPROM hardware.
> > >
> > > There currently is a major problem with this:
> > > It tries to deduce a MAC address from various hardware parameters. But
> > > currently it will result in the same MAC address for machines of the
> > > same type. Does somebody have an idea of some device-instance specific
> > > serial number or something similar that could be hashed into the MAC?
> >
> > You might look at the "root=" part of /proc/cmdline. Mine says
> > "root=/dev/disk/by-id/ata-TOSHIBA_MK2546GSX_18C2P0KCT-part1". That disk
> > serial number would certainly be unique. Even if it just said
> > "root=/dev/sda1", it would be repeatable.
> 
> Ok, I think this is getting ugly :)
> The problem with all this is that if you change the harddisk, or change the
>  partitioning, the wireless mac address would change. That would surely
>  lead to confusion.
> 
> I think we probably have to drop this patch and instead do a mechanism that
> fetches the sprom from userspace, if the card doesn't have one.

I am ok with that solution.

> This way we
> can have a script in userspace that generates the image based on the PCI ID
> information and just randomizes the MAC address once. The firmware loading
> mechanism would be useful for that.
> In case of an embedded device with the MAC in the nvram, the kernel can
>  still override the mac address provided by userspace.

Yes, this is fine.
--
WBR, Florian