Re: CONFIG_PRINTK doesn't makes size smaller

[Vadim Lobanov <vlobanov@speakeasy.net>]

On Tue, 20 Sep 2005, Andrey Panin wrote:

> On 263, 09 20, 2005 at 02:14:55PM +0800, colin wrote:
> >
> > Hi there,
> > I tried to make kernel with CONFIG_PRINTK off. I considered it should become
> > smaller, but it didn't because it actually isn't an empty function, and
> > there are many copies of it in vmlinux, not just one. Here is its
> > definition:
> >     static inline int printk(const char *s, ...) { return 0; }
> >
> > I change the definition to this and it can greatly reduce the size by about
> > 5%:
> >     #define printk(...) do {} while (0)
> > However, this definition would lead to error in some situations. For
> > example:
> >     1. (printk)
> >     2. ret = printk
> >
> > I hope someone could suggest a better definition of printk that can both
> > make printk smaller and eliminate errors.
>
> What about the macro below ?
>
> #define printk(...) ({ do { } while(0); 0; })

So what does the do-while loop give us in the above case? In other
words, why not just do the following...?

#define printk(...) ({ 0; })

-VadimL