Re: [PATCH RFC] introduce pm_call() macro to get rid of most#ifdef CONFIG_PM

[Anton Vorontsov]

On Sun, Mar 02, 2008 at 04:08:20PM -0800, Arjan van de Ven wrote:
> On Mon, 3 Mar 2008 02:43:08 +0300
> Anton Vorontsov <cbouatmailru@xxxxxxxxx> wrote:
> 
> > Currently drivers handle CONFIG_PM this way:
> > 
> > #ifdef CONFIG_PM
> > drv_suspend() {}
> > drv_resume() {}
> > #else
> > #define drv_suspend NULL
> > #define drv_resume NULL
> > #endif
> > 
> > struct driver drv = {
> > 	.suspend = drv_suspend,
> > 	.resume = drv_resume,
> > };
> > 
> > With this patch, the code above converts into:
> > 
> > drv_suspend() {}
> > drv_resume() {}
> > 
> > struct driver drv = {
> > 	.suspend = pm_call(drv_suspend),
> > 	.resume = pm_call(drv_resume),
> > };
> > 
> > GCC will optimize away suspend/resume calls if they're really
> > not used.
> > 
> 
> 
> to be honest, at this point I would think it's time to remove
> CONFIG_PM, or rather,
> just make it always be there and just get rid of the ifdefs.

Don't be so CONFIG_PM-centric :-)

$ zcat /proc/config.gz | grep CONFIG_PM
# CONFIG_PM is not set

This is machine I use at home.

> We're saving 2 words and a bit of code,
> but only a case that not even the embedded guys use. 

Well, on my ARM machine, with CONFIG_PM=y vmlinux grows by 30KB, half
of that is in drivers/. 30KB is 1% of the vmlinux. Is it enough to
worth saving? I don't know.

On a x86 box, CONFIG_PM=y grows the vmlinux by 400KB (yeah, it's
including ACPI and stuff), though here I didn't count drivers'
suspend/resume hooks contribution share.

-- 
Anton Vorontsov
email: cbouatmailru@xxxxxxxxx
irc://irc.freenode.net/bd2
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/