Re: ->direct_IO API change in current 2.4 BK

[Jeff Garzik <jgarzik@pobox.com>]

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