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Message-ID: <3ef38b44-a584-d6c4-5d3b-ed2fdfb743ee@gmail.com>
Date: Sat, 25 Jan 2020 19:11:49 -0800
From: Florian Fainelli <f.fainelli@...il.com>
To: Leon Romanovsky <leon@...nel.org>
Cc: "David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Michal Kubecek <mkubecek@...e.cz>,
Michal Kalderon <michal.kalderon@...vell.com>,
linux-netdev <netdev@...r.kernel.org>,
RDMA mailing list <linux-rdma@...r.kernel.org>
Subject: Re: [PATCH net-next v1] net/core: Replace driver version to be kernel
version
On 1/25/2020 11:24 AM, Leon Romanovsky wrote:
> On Sat, Jan 25, 2020 at 08:49:58PM +0200, Leon Romanovsky wrote:
>> On Sat, Jan 25, 2020 at 08:55:01AM -0800, Florian Fainelli wrote:
>>>
>>>
>>> On 1/25/2020 8:14 AM, Leon Romanovsky wrote:
>>>> From: Leon Romanovsky <leonro@...lanox.com>
>>>>
>>>> In order to stop useless driver version bumps and unify output
>>>> presented by ethtool -i, let's overwrite the version string.
>>>>
>>>> Before this change:
>>>> [leonro@...er ~]$ ethtool -i eth0
>>>> driver: virtio_net
>>>> version: 1.0.0
>>>> After this change:
>>>> [leonro@...ver ~]$ ethtool -i eth0
>>>> driver: virtio_net
>>>> version: 5.5.0-rc6+
>>>>
>>>> Signed-off-by: Leon Romanovsky <leonro@...lanox.com>> ---
>>>> Changelog:
>>>> v1: Resend per-Dave's request
>>>> https://lore.kernel.org/linux-rdma/20200125.101311.1924780619716720495.davem@davemloft.net
>>>> No changes at all and applied cleanly on top of "3333e50b64fe Merge branch 'mlxsw-Offload-TBF'"
>>>> v0: https://lore.kernel.org/linux-rdma/20200123130541.30473-1-leon@kernel.org
>>>
>>> There does not appear to be any explanation why we think this is a good
>>> idea for *all* drivers, and not just the ones that are purely virtual?
>>
>> We beat this dead horse too many times already, latest discussion and
>> justification can be found in that thread.
>> https://lore.kernel.org/linux-rdma/20200122152627.14903-1-michal.kalderon@marvell.com/T/#md460ff8f976c532a89d6860411c3c50bb811038b
>>
>> However, it was discussed in ksummit mailing list too and overall
>> agreement that version exposed by in-tree modules are useless and
>> sometimes even worse. They mislead users to expect some features
>> or lack of them based on this arbitrary string.
>>
>>>
>>> Are you not concerned that this is ABI and that specific userland may be
>>> relying on a specific info format and we could now be breaking their
>>> version checks? I do not disagree that the version is not particularly
>>> useful for in-tree kernel, but this is ABI, and breaking user-space is
>>> usually a source of support questions.
>>
>> See this Linus's response:
>> "The unified policy is pretty much that version codes do not matter, do
>> not exist, and do not get updated.
>>
>> Things are supposed to be backwards and forwards compatible, because
>> we don't accept breakage in user space anyway. So versioning is
>> pointless, and only causes problems."
>> https://lore.kernel.org/ksummit-discuss/CA+55aFx9A=5cc0QZ7CySC4F2K7eYaEfzkdYEc9JaNgCcV25=rg@mail.gmail.com/
>>
>> I also don't think that declaring every print in the kernel as ABI is
>> good thing to do. We are not breaking binary ABI and continuing to
>> supply some sort of versioning, but in unified format and not in wild
>> west way like it is now.
>>
>> So bottom line, if some REAL user space application (not test suites) relies
>> on specific version reported from ethtool, it is already broken and can't work
>> sanely for stable@, distros and upstream kernels.
>
> And about support questions,
> I'm already over-asked to update our mlx5 driver version every time some
> of our developers adds new feature (every week or two), which is insane.
> So I prefer to have one stable solution in the kernel.
Fair enough, can you spin a new version which provides this background
discussion and links into your commit message?
--
Florian
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