Date:	Mon, 12 Dec 2011 14:49:49 -0800
From:	"Luis R. Rodriguez" <mcgrof@...jolero.org>
To:	Ben Hutchings <ben@...adent.org.uk>
Cc:	"John W. Linville" <linville@...driver.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Dave Jones <davej@...hat.com>, Greg KH <greg@...ah.com>,
	Debian kernel maintainers <debian-kernel@...ts.debian.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	linux-wireless <linux-wireless@...r.kernel.org>
Subject: Re: [PATCH] module,bug: Add TAINT_OOT_MODULE flag for modules not
 built in-tree

On Mon, Dec 12, 2011 at 2:47 PM, Luis R. Rodriguez <mcgrof@...jolero.org> wrote:
> On Mon, Dec 12, 2011 at 1:58 PM, Ben Hutchings <ben@...adent.org.uk> wrote:
>> On Mon, Dec 12, 2011 at 01:40:44PM -0800, Luis R. Rodriguez wrote:
>>> On Mon, Oct 24, 2011 at 6:12 AM, Ben Hutchings <ben@...adent.org.uk> wrote:
>>> > Use of the GPL or a compatible licence doesn't necessarily make the code
>>> > any good.  We already consider staging modules to be suspect, and this
>>> > should also be true for out-of-tree modules which may receive very
>>> > little review.
>>> >
>>> > Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
>>> > ---
>>> > Debian has been carrying this for the last few kernel versions.  The
>>> > recent thread '[RFC] virtualbox tainting.' and discussions at KS suggest
>>> > that this might be more generally useful.
>>>
>>> This indeed seems like a good idea to advocate getting things upstream
>>> (not just staging) but what about the case where we have upstream
>>> drivers from future kernels backported to older kernels and the newer
>>> driver is simply provided as a feature for users who may need new
>>> features / chipset support on their old distribution kernel?
>>
>> They continue to work without any loss of functionality.  (After the
>> follow-up patches to keep dynamic debugging and lock debugging
>> working.)
>
> Great!
>
>>> It seems this taint flag will be used for driers backported through
>>> compat-wireless, the compat kernel module or any other backported
>>> driver, even if it is indeed upstream and whereby kernel developer
>>> *do* commit to actually fixing issues. In our experience
>>> compat-wireless bugs *are real bugs*, not backport bugs so we do look
>>> into them. In our latest linux-next.git based release for example
>>> backport code consists only of 1.3804% of the code.
>>
>> Now you can look for (O) after the module name in a BUG/Oops message
>> and you can tell whether the user really had the original or
>> compat-wireless version of the driver.
>>
>> It is really up to each distributor or developer how they treat
>> bug reports with the O taint.  When handling Debian bug reports I
>> won't automatically reject such a tainted kernel but I will look
>> carefully at the module list.
>
> I'm working on getting my companies to abandon 802.11 proprietary
> drivers for good. For Station mode of operation this is pretty much
> mission complete. For AP products.. this is work in progress. The out
> of tree flag is a good utility one can use to help justify working
> upstream but if we treat any future-kernel-backported-driver equally
> to any out of tree crap piece of shit driver, it seems to do unjustice
> to the value of a properly upstream backported driver. I will note
> that I put a lot of effort to ensure that the backport effort is
> upstream-centric in an *extremely* upstream-biased way, see how I
> label extra patches for tarballs [1]. If your patches are not upstream
> the only way you get into these tarballs are by providing patches into
> these directories:
>
>  * pending-stable/ stable fixes from linux-next.git not yet on a stable release
>  * linux-next-cherry-picks/ patches upstream but that won't go to the
> stable release that we want to cherry pick
>  * linux-next-pending/ patches posted on the public development
> mailing list, patch not yet merged due to the maintainer being away on
> vacation or whatever
>  * crap/ patches not even posted publicly yet
>
> Each tarball used also gets pegged with a letter if *any* patch from
> any of these directories gets applied. The compat module, upon being
> loaded, will also print the kernel ring buffer the exact release,
> whether extra patches were provided, the upstream git tree used as
> base and so on.
>
> So -- although from a technical perspective this may mean Debian /
> other kernel developers may ignore the taint flag for compat-wireless
> it'd sure be nice to avoid it for them all together. Just can't think
> of a way to do it yet... If you agree should we continue to think of a
> way if its possible?
>
> [1] http://wireless.kernel.org/en/users/Download/stable#Legend

How about a way to peg a driver as a backport from future kernels?
Like maybe MODULE_COMPAT() ?

  Luis
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