Re: ->direct_IO API change in current 2.4 BK

Jeff Garzik (jgarzik@pobox.com)
Wed, 09 Jul 2003 20:21:25 -0400


Alan Cox wrote:
> On Mer, 2003-07-09 at 20:13, Marcelo Tosatti wrote:
>
>>I applied it because, in my ignorance, I did not noticed it would break
>>the stable API.
>>
>>I applied it because I wanted comments useful from people (Like hch and
>>others did).
>
>
> I'm not sure I see what the fuss is about a slight API change that is
> safe since it spews warnings/breaks existing code that isnt fixed. At
> least one vendor kernel also has the changed API anyway

"safe" ignores the pain of people trying to support multiple kernels.
Each API change like the direct_IO one introduces ifdefs. Changing a
function prototype is particularly annoying because you can't create a
backwards-compat wrapper

I disagree with the AC97 codec changes being merged into 2.4, too, for
the same reason. Yes I recognize it is required to support new
hardware. Yes I realize it vastly simplifies supporting some existing
hardware. But I don't think you realize (or don't care?) about the
maintenance pain created by the change. If a vendor wishes their driver
to support 2.4.21 _and_ 2.4.22 (not a lot to ask), they must add a bunch
of ifdef crud in their OSS driver.

Feature and API additions are _far_ less painful than API changes in the
middle of a stable series.

Overall, I think we are looking at a question which needs to be answered
by the community: what constitutes a stable series? when do we stop
changing the API and let it stabilize? ... and I am writing a mail
right now to ask that question (as requested by Marcelo and a couple
others, though I wanted to do it for a while now).

Jeff

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