* [PATCH] ib_ehca: fix compile failure on ppc64
@ 2012-02-27 22:02 Kyle McMartin
[not found] ` <20120227220255.GE29211-nxOev/eQj6CGu0OVIAPS5KfLeoKvNuZc@public.gmane.org>
0 siblings, 1 reply; 4+ messages in thread
From: Kyle McMartin @ 2012-02-27 22:02 UTC (permalink / raw)
To: linux-rdma-u79uwXL29TY76Z2rM5mHXA
Cc: hnguyen-tA70FqPdS9bQT0dZR+AlfA, raisch-tA70FqPdS9bQT0dZR+AlfA
I'm getting compile failures building this driver, which I narrowed down
to the ilog2 call in ehca_get_max_hwpage_size...
ERROR: ".____ilog2_NaN" [drivers/infiniband/hw/ehca/ib_ehca.ko]
undefined!
make[1]: *** [__modpost] Error 1
make: *** [modules] Error 2
The use of shca->hca_cap_mr_pgsize is confusing the compiler, and
resulting in the __builtin_constant_p in ilog2 going insane.
I tried making it take the u32 pgsize as an argument and the expansion
of shca->_pgsize in the caller, but that failed as well. Adding a
temporary variable as below got it building again though (as did
replacing the ilog2 with fls(x) - 1.)
With this patch in place, the driver compiles on my GCC 4.6.2 here.
Signed-off-by: Kyle McMartin <kmcmarti-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
--- a/drivers/infiniband/hw/ehca/ehca_mrmw.c
+++ b/drivers/infiniband/hw/ehca/ehca_mrmw.c
@@ -112,7 +112,8 @@ 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);
+ u32 pgsize = shca->hca_cap_mr_pgsize;
+ return 1UL << ilog2(pgsize);
}
static struct ehca_mr *ehca_mr_new(void)
--
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] ib_ehca: fix compile failure on ppc64
[not found] ` <20120227220255.GE29211-nxOev/eQj6CGu0OVIAPS5KfLeoKvNuZc@public.gmane.org>
@ 2012-02-28 5:18 ` Roland Dreier
[not found] ` <CAL1RGDXjF-Y-UABiondu6y9k9HRoxgE9oVAbp-BJ4x+iuRjiWg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
0 siblings, 1 reply; 4+ messages in thread
From: Roland Dreier @ 2012-02-28 5:18 UTC (permalink / raw)
To: Kyle McMartin
Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA,
hnguyen-tA70FqPdS9bQT0dZR+AlfA, raisch-tA70FqPdS9bQT0dZR+AlfA
On Mon, Feb 27, 2012 at 2:02 PM, Kyle McMartin <kmcmartin-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 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...
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...
- R.
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] ib_ehca: fix compile failure on ppc64
[not found] ` <CAL1RGDXjF-Y-UABiondu6y9k9HRoxgE9oVAbp-BJ4x+iuRjiWg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
@ 2012-02-28 15:15 ` Kyle McMartin
[not found] ` <20120228151545.GF29211-nxOev/eQj6CGu0OVIAPS5KfLeoKvNuZc@public.gmane.org>
0 siblings, 1 reply; 4+ messages in thread
From: Kyle McMartin @ 2012-02-28 15:15 UTC (permalink / raw)
To: Roland Dreier
Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA,
hnguyen-tA70FqPdS9bQT0dZR+AlfA, raisch-tA70FqPdS9bQT0dZR+AlfA
On Mon, Feb 27, 2012 at 09:18:35PM -0800, Roland Dreier wrote:
> On Mon, Feb 27, 2012 at 2:02 PM, Kyle McMartin <kmcmartin-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> 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 <roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org>
Signed-off-by: Kyle McMartin <kmcmarti-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
--- 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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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] ib_ehca: fix compile failure on ppc64
[not found] ` <20120228151545.GF29211-nxOev/eQj6CGu0OVIAPS5KfLeoKvNuZc@public.gmane.org>
@ 2012-03-19 10:05 ` Hoang-Nam Nguyen
0 siblings, 0 replies; 4+ messages in thread
From: Hoang-Nam Nguyen @ 2012-03-19 10:05 UTC (permalink / raw)
To: Kyle McMartin, Roland Dreier
Cc: Christoph Raisch, linux-rdma-u79uwXL29TY76Z2rM5mHXA
The patch below looks fine to me.
Sorry for this so late reply.
Thanks!
Nam
Kyle McMartin <kmcmartin-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote on 02/28/2012 04:15:46 PM:
> From:
>
> Kyle McMartin <kmcmartin-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>
> To:
>
> Roland Dreier <roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org>
>
> Cc:
>
> linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, 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 <kmcmartin-H+wXaHxf7aJhl2p70BpVqQ@public.gmane.orgm>
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 <roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org>
> Signed-off-by: Kyle McMartin <kmcmarti-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>
> --- 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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^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-03-19 10:05 UTC | newest]
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2012-02-27 22:02 [PATCH] ib_ehca: fix compile failure on ppc64 Kyle McMartin
[not found] ` <20120227220255.GE29211-nxOev/eQj6CGu0OVIAPS5KfLeoKvNuZc@public.gmane.org>
2012-02-28 5:18 ` Roland Dreier
[not found] ` <CAL1RGDXjF-Y-UABiondu6y9k9HRoxgE9oVAbp-BJ4x+iuRjiWg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-02-28 15:15 ` Kyle McMartin
[not found] ` <20120228151545.GF29211-nxOev/eQj6CGu0OVIAPS5KfLeoKvNuZc@public.gmane.org>
2012-03-19 10:05 ` Hoang-Nam Nguyen
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