Re: [PATCH 1/3] perf events: fix WARN_ON_ONCE for 64-bit raw data, SW events

Peter Zijlstra
2011-02-18T17:13:37Z

On Fri, 2011-02-18 at 15:04 -0200, Arnaldo Carvalho de Melo wrote:
> Em Fri, Feb 18, 2011 at 04:01:31PM +0100, Peter Zijlstra escreveu:
> > On Fri, 2011-02-18 at 12:53 -0200, Arnaldo Carvalho de Melo wrote:
> > > > So size should be changed to u64 rather than modifying the
> > > WARN_ON_ONCE?
> > >
> > > Yeah, I guess so, 32-bit has to die it seems, gets in the way of
> > > testing
> > > :-)
> >
> > No!
> >
> > 1) don't use RAW unless you have to
> > 2) you don't have to, goto 1
> > 3) if you do anyway, ensure its properly padded
>
> Ok, but using that struct definition on 32-bit land, will lead to non 8 byte
> alignment, right?

Nope, its just fine.. it defaults to an empty 4byte payload ;-)

Its just that any custom payload must be of size 4+8*n bytes.