Re: [RFC] New kernel-message logging API (take 2)

["Vegard Nossum" <vegard.nossum@gmail.com>]

On 9/28/07, Kyle Moffett <mrmacman_g4@mac.com> wrote:
> On Sep 28, 2007, at 03:31:11, Geert Uytterhoeven wrote:
> > Can't you store the loglevel in the kprint_block and check it in
> > all successive kprint_*() macros? If gcc knows it's constant, it
> > can optimize the non-wanted code away. As other fields in struct
> > kprint_block cannot be constant (they store internal state), you
> > have to split it like:
> >
> >     struct kprint_block {
> >           int loglevel;
> >           struct real_kprint_block real;  /* internal state */
> >     }
> >
> > and pass &block.real() instead of &block to all successive internal
> > functions.  I haven't tried this, so let's hope gcc is actually
> > smart enough...
>
> Well actually, I believe you could just do:
>
> struct kprint_block {
>         const int loglevel;
>         [...];
> };
>
> Then cast away the constness to actually set it initially:
> *((int *)&block.loglevel) = LOGLEVEL;

This doesn't seem to work either (i.e. it is not optimized out). I
tried initializing the struct statically too, to no avail. But thanks
for the tip.

Vegard