Subject: Re: New iwlwifi 3945 uCode available
From: reinette chatre <reinette.chatre@linux.intel.com>
To: Marcel Holtmann <holtmann@linux.intel.com>
Cc: Johannes Berg <johannes@sipsolutions.net>,
	Tomas Winkler <tomasw@gmail.com>,
	"John W. Linville" <linville@tuxdriver.com>,
	"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
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Date: Wed, 22 Oct 2008 13:30:46 -0700
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Sender: linux-wireless-owner@vger.kernel.org

On Wed, 2008-10-22 at 00:56 -0700, Marcel Holtmann wrote:
> Hi Johannes,
> 
> > > I do not believe our request is unreasonable. If a user runs a new
> > > kernel the log will print a message that the firmware is incorrect ...
> > > all the user needs to do is go to
> > > http://intellinuxwireless.org/?n=Downloads and download the latest
> > > firmware.
> >
> > And that exactly _is_ a problem, the user may be relying on wireless
> > connectivity. And they won't know up-front they need new firmware. Since
> > firmware is loaded from userspace, you're breaking userspace/kernel ABI,
> > it's pretty simple really.
> 
> I talked to David Woodhouse and we plan to add a big warning to
> modules_install when MODULE_FIRMWARE is not present on the filesystem.

Thank you very much. This appears to address the problem. That is, a
user trying to run a new kernel with old userspace will now get a
warning while internet access is still available. Thus enabling them to
update firmware. Is this solution acceptable to everybody?

> 
> > I really don't know why we let you get away with this and bitch
> > endlessly when b43 does such a change, to the point where we finally
> > cave in and support both versions. Why should a community-supported
> > driver be held to higher standards?
> 
> If in any way possible, we should support both versions of the firmware.

I would like to hear some suggestions on how we can do this as I am not
familiar with the other drivers. The driver is closely tied to the
firmware ... and I am actually tempted to draw an analogy between the
interface between the driver and mac80211 here. From what I understand,
for the driver to support many versions of the firmware it dynamically
needs to detect which features are supported at runtime and act
accordingly. This is a hard problem. What am I missing?

Reinette