On Wed, Sep 12, 2007 at 12:43:42AM +0200, Matteo Croce wrote:
> > > --- a/arch/mips/kernel/traps.c
> > > +++ b/arch/mips/kernel/traps.c
> > > @@ -1075,9 +1075,23 @@ void *set_except_vector(int n, void *addr)
> > >
> > > exception_handlers[n] = handler;
> > > if (n == 0 && cpu_has_divec) {
> > > +#ifdef CONFIG_AR7
> > > + /* lui k0, 0x0000 */
> > > + *(volatile u32 *)(CAC_BASE+0x200) =
s/CAC_BASE/ebase/
> > > + 0x3c1a0000 | (handler >> 16);
> > > + /* ori k0, 0x0000 */
> > > + *(volatile u32 *)(CAC_BASE+0x204) =
> > > + 0x375a0000 | (handler & 0xffff);
> > > + /* jr k0 */
> > > + *(volatile u32 *)(CAC_BASE+0x208) = 0x03400008;
> > > + /* nop */
> > > + *(volatile u32 *)(CAC_BASE+0x20C) = 0x00000000;
> > > + flush_icache_range(CAC_BASE+0x200, CAC_BASE+0x210);
All these volatile keywords are unnecessary btw.
You may want to read Documentation/volatile-considered-harmful.txt on
why volatile is almost always a bad idea.
> > > +#else
> > > *(volatile u32 *)(ebase + 0x200) = 0x08000000 |
> > > (0x03ffffff & (handler >> 2));
Just like this one, so I will remove it now.
> > > flush_icache_range(ebase + 0x200, ebase + 0x204);
> > > +#endif
> > > }
> > > return (void *)old_handler;
> > > }
> >
> > Runtime checking, something like this would be better than ifdef:
> >
> > if ((handler ^ (ebase + 4)) & 0xfc000000)
> > /* use jr */
> > ...
> > } else {
> > /* use j */
> > ...
> > }
> This will not make the code bigger?
It will by a miniscule amount. Which hardly matters because the function
is (whops, should be ...) __init code anyway.
> What's wrong with #ifdef?
#ifdef makes for harder to read code (To paraphrase Linus - the kernel is
write once and read 10 million times) , is less flexible and has a tendence
to hide bugs in the deactivated part. So generally avoid.
And actually in this specific case it also should be a runtime decission
simply because in the not so distant future the will be hardware which
will simply need that.
Ralf
