Re: [RFCLUE3] flagging kernel interface changes

[Jesper Juhl]

On 15/11/06, William D Waddington <william.waddington@xxxxxxxxxx> wrote:
> I tried submitting a patch a while back:
> "[PATCH] IRQ: ease out-of-tree migration to new irq_handler prototype"
> to add #define __PT_REGS to include/linux/interrupt.h to flag the change
> to the new interrupt handler prototype.  It wasn't well received :(
>
> No big surprise.  The #define wasn't my idea and I hadn't submitted a
> patch before.  I wanted to see how the patch procedure worked, and
> hoped that the flag would be included so I could mod my drivers and
> move on...
>
> What I'm curious about is why flagging kernel/driver interface changes
> is considered a bad idea.  From my point of view as a low-life out-of-
> tree driver maintainer,
>
> #ifdef NEW_INTERFACE
> #define <my new internals>
> #endif
>
> (w/maybe an #else...)
>
> is cleaner and safer than trying to track specific kernel versions in
> a multi-kernel-version driver.  It seems that in some cases, the new
> interface has been, like HAVE_COMPAT_IOCTL for instance.
>
> I don't want to start an argument about "stable_api_nonsense" or the
> wisdom of out-of-tree drivers.  Just curious about the - why - and
> whether it is indifference or antagonism toward drivers outside the
> fold. Or ???

I would say that one reason is that cluttering up the kernel with
#ifdef's is ugly and annoying to maintain long-term. Especially when
it's expected that anyone who changes in-kernel interfaces also fix up
any user(s) of those interfaces, so the #ifdef's are pointless
(ignoring out-of-tree code that is).


--
Jesper Juhl <jesper.juhl@xxxxxxxxx>
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