linux-kernel - Re: [PATCH 2/2] amdgpu/dc/dml: Support clang option for stack alignment

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Message-ID: <20180208013730.GC116483@google.com>
Date:   Wed, 7 Feb 2018 17:37:30 -0800
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Guenter Roeck <groeck@...gle.com>
Cc:     Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        David Zhou <David1.Zhou@....com>,
        David Airlie <airlied@...ux.ie>,
        Harry Wentland <harry.wentland@....com>,
        Felix Kuehling <Felix.Kuehling@....com>,
        Dmytro Laktyushkin <Dmytro.Laktyushkin@....com>,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        Maling list - DRI developers 
        <dri-devel@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Guenter Roeck <groeck@...omium.org>,
        Justin TerAvest <teravest@...omium.org>,
        Craig Bergstrom <craigb@...omium.org>
Subject: Re: [PATCH 2/2] amdgpu/dc/dml: Support clang option for stack
 alignment

El Wed, Feb 07, 2018 at 05:34:44PM -0800 Guenter Roeck ha dit:

> On Wed, Feb 7, 2018 at 5:21 PM, Matthias Kaehlcke <mka@...omium.org> wrote:
> > DML uses the compiler option -mpreferred-stack-boundary=4 to configure
> > a stack alignment of 16 bytes. Clang uses the option -mstack-alignment
> > instead, which expects as parameter the alignment in bytes, and not a
> > power of two like -mpreferred-stack-boundary.
> >
> > Probe for both compiler options and use the correct one, similar to
> > what is done in arch/x86/Makefile.
> >
> > Reported-by: Guenter Roeck <groeck@...omium.org>
> > Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> > ---
> >  drivers/gpu/drm/amd/display/dc/dml/Makefile | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/dc/dml/Makefile b/drivers/gpu/drm/amd/display/dc/dml/Makefile
> > index b8cadf833e71..740975931d21 100644
> > --- a/drivers/gpu/drm/amd/display/dc/dml/Makefile
> > +++ b/drivers/gpu/drm/amd/display/dc/dml/Makefile
> > @@ -24,7 +24,13 @@
> >  # It provides the general basic services required by other DAL
> >  # subcomponents.
> >
> > -subdir-ccflags-y += -mhard-float -msse -mpreferred-stack-boundary=4
> > +ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
> > +       cc_stack_align=-mpreferred-stack-boundary=4
> > +else ifneq ($(call cc-option, -mstack-alignment=16),)
> > +       cc_stack_align := -mstack-alignment=16
> > +endif
> > +
> Any reason for using both = and := ?

Not really, will fix.

Thanks!