Re: [PATCH 7/24] consolidate msr.h

Ingo Molnar
2007-11-20T05:52:15Z

* Steven Rostedt <rostedt@goodmis.org> wrote:

> > On Fri, Nov 09, 2007 at 04:42:48PM -0200, Glauber de Oliveira Costa wrote:
> > > - wrmsrl(MSR_CSTAR, ia32_cstar_target);
> > > + wrmsrl(MSR_CSTAR, (u64)ia32_cstar_target);
> >
> > Hmm, why do you add explicit casts? The compiler should convert that
> > correctly on its own.
> >
> > > +static inline void wrmsrl(unsigned int msr, unsigned long long val)
> >
> > Hmm, long long is 64 bit on all x86, but why not use explicit u64 to
> > show that?
>
> (quick reply)
>
> With PVOPS on it gives compiler warnings without that explict cast.
> Without looking at the code, IIRC with non-PVOPS it is a macro
> directly into asm, so it didn't matter what the cast was. But with
> PVOPS as a function, it gave compiler warnings.
>
> Take it out and try compiling it for both i386 and x86_64. One of them
> gave warnings. But maybe it's not a problem now.

i dont think there's ever any true need (and good cause) to force
integer type casts like that at the callee site.

Ingo