From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [Ksummit-2013-discuss] [RFC] of: Allow for experimental device tree bindings
Date: Fri, 25 Oct 2013 09:45:05 +0100 [thread overview]
Message-ID: <526A2F91.1070408@wwwdotorg.org> (raw)
In-Reply-To: <20131025082229.GD19622@ulmo.nvidia.com>
On 10/25/2013 09:22 AM, Thierry Reding wrote:
> On Thu, Oct 24, 2013 at 11:26:19PM +0100, Stephen Warren wrote:
>> On 10/23/2013 07:51 PM, Thierry Reding wrote:
>>> On Wed, Oct 23, 2013 at 05:05:32PM +0100, David Woodhouse
>>> wrote:
>>>> On Wed, 2013-10-23 at 17:06 +0200, Thierry Reding wrote:
>>>>> + /* check if binding is experimental */ + if
>>>>> (dev != device || drv != driver) { +
>>>>> pr_warn("of: device %s (%s) uses an experimental
>>>>> binding\n", + np->name,
>>>>> np->full_name); +
>>>>
>>>> In the discussions earlier I think we decided that this
>>>> should set a taint flag too.
>>>
>>> A taint flag seems somewhat drastic. It's not like using an
>>> experimental binding should have an influence on the stability
>>> of the running kernel. I always thought that taint flags were
>>> supposed to flag conditions where code of unknown origin or
>>> code known to be broken was being executed because they may
>>> destabilize the running kernel.
>>>
>>> The worst that should happen if you run an experimental binding
>>> is that some part of the system will just not come up.
>>
>> IIRC, the purpose of the taint flag was to make it clear that the
>> kernel or DT was not expected to function in the future, so don't
>> be surpised if you upgrade it, and it stops working, without you
>> taking explicit action, such as revising your DT to match the new
>> kernel or vice-versa.
>
> I understand that, but I was arguing that it doesn't match existing
> uses of taint flags. The various flags that are currently defined
> all seem to be set whenever some event occurs that could cause
> instability of the currently running system, such as loading a
> proprietary or out-of-tree module, forcing a module to be loaded,
> overriding firmware parameters...
Executing a driver that supports an unstable binding does produce
instability in the system; the kernel configuration might not continue
to work if rebooted with an updated DT. Admittedly, this is a slightly
different concept than other taint flags, but seems like a logical
extension.
next prev parent reply other threads:[~2013-10-25 8:45 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-23 15:06 [RFC] of: Allow for experimental device tree bindings Thierry Reding
2013-10-23 16:05 ` [Ksummit-2013-discuss] " David Woodhouse
2013-10-23 16:55 ` Guenter Roeck
2013-10-23 17:05 ` David Woodhouse
2013-10-23 18:56 ` Thierry Reding
2013-10-23 18:51 ` Thierry Reding
2013-10-24 22:26 ` Stephen Warren
2013-10-25 8:22 ` Thierry Reding
2013-10-25 8:45 ` Stephen Warren [this message]
2013-10-23 16:33 ` Stephen Warren
2013-10-23 17:20 ` [Ksummit-2013-discuss] " Wolfram Sang
2013-10-23 18:59 ` Thierry Reding
2013-10-23 19:34 ` Jason Gunthorpe
2013-10-23 19:58 ` Thierry Reding
2013-10-23 21:08 ` Jason Gunthorpe
2013-10-24 8:04 ` Thierry Reding
2013-10-24 17:32 ` Jason Gunthorpe
2013-10-23 21:13 ` Andy Lutomirski
2013-10-23 19:40 ` Wolfram Sang
2013-10-23 20:05 ` Thierry Reding
2013-10-24 8:34 ` Grant Likely
2013-10-24 8:50 ` Thierry Reding
2013-10-24 20:26 ` Matt Sealey
2013-10-24 22:29 ` Stephen Warren
2013-10-24 18:39 ` jonsmirl at gmail.com
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