The patch below looks fine to me.
Sorry for this so late reply.
Thanks!
Nam

Kyle McMartin <[email protected]> wrote on 02/28/2012 04:15:46 PM:

> From:
>
> Kyle McMartin <[email protected]>
>
> To:
>
> Roland Dreier <[email protected]>
>
> Cc:
>
> [email protected], Hoang-Nam Nguyen/Germany/IBM@IBMDE,
> Christoph Raisch/Germany/IBM@IBMDE
>
> Date:
>
> 02/28/2012 04:15 PM
>
> Subject:
>
> Re: [PATCH] ib_ehca: fix compile failure on ppc64
>
> On Mon, Feb 27, 2012 at 09:18:35PM -0800, Roland Dreier wrote:
> > On Mon, Feb 27, 2012 at 2:02 PM, Kyle McMartin <[email protected]>
wrote:
> > >  static u64 ehca_get_max_hwpage_size(struct ehca_shca *shca)
> > >  {
> > > -       return 1UL << ilog2(shca->hca_cap_mr_pgsize);
> > > +       u32 pgsize = shca->hca_cap_mr_pgsize;
> > > +       return 1UL << ilog2(pgsize);
> > >  }
> >
> > How about using rounddown_pow_of_two(shca->hca_cap_mr_pgsize)?
> > Does that build?  Because that seems to me to be a cleaner way of
> > expressing this anyway...
> >
>
> Yeah, that works too, good catch, I should have noticed that sooner.
>
> > Something about that ilog2() implementation seems to trigger gcc
> > bugs, I seem to remember some other bogus compile failure on
> > sparc involving it as well...
> >
>
> I suspect it's the 64 deep trinary operators ;-) (It seems to trip up on
> the __builtin_constant_p and hit the second ____ilog2_NaN) It's a pretty
> weird .config dependent bug, I'm very confused by it.
>
> Suggested-by: Roland Dreier <[email protected]>
> Signed-off-by: Kyle McMartin <[email protected]>
>
> --- a/drivers/infiniband/hw/ehca/ehca_mrmw.c
> +++ b/drivers/infiniband/hw/ehca/ehca_mrmw.c
> @@ -112,7 +112,7 @@ static u32 ehca_encode_hwpage_size(u32 pgsize)
>
>  static u64 ehca_get_max_hwpage_size(struct ehca_shca *shca)
>  {
> -   return 1UL << ilog2(shca->hca_cap_mr_pgsize);
> +   return rounddown_pow_of_two(shca->hca_cap_mr_pgsize);
>  }
>
>  static struct ehca_mr *ehca_mr_new(void)
>

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