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Subject: Re: [PATCH 09/10] powerpc: Enable OpenCAPI Storage Class Memory
 driver on bare metal
From:   "Alastair D'Silva" <alastair@au1.ibm.com>
To:     Frederic Barrat <fbarrat@linux.ibm.com>
Cc:     Oscar Salvador <osalvador@suse.com>,
        Madhavan Srinivasan <maddy@linux.vnet.ibm.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        David Hildenbrand <david@redhat.com>,
        Wei Yang <richard.weiyang@gmail.com>,
        Keith Busch <keith.busch@intel.com>, linux-mm@kvack.org,
        Michal Hocko <mhocko@suse.com>,
        Paul Mackerras <paulus@samba.org>,
        Ira Weiny <ira.weiny@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Pavel Tatashin <pasha.tatashin@soleen.com>,
        Dave Jiang <dave.jiang@intel.com>, linux-nvdimm@lists.01.org,
        Vishal Verma <vishal.l.verma@intel.com>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Anju T Sudhakar <anju@linux.vnet.ibm.com>,
        Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>,
        Andrew Donnellan <ajd@linux.ibm.com>,
        Arnd Bergmann <arnd@arndb.de>, Greg Kurz <groug@kaod.org>,
        Qian Cai <cai@lca.pw>,
        =?ISO-8859-1?Q?C=E9dric?= Le Goater <clg@kaod.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Hari Bathini <hbathini@linux.ibm.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org,
        Vasant Hegde <hegdevasant@linux.vnet.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linuxppc-dev@lists.ozlabs.org
Date:   Fri, 31 Jan 2020 15:56:58 +1100
In-Reply-To: <3ba57ce6-9135-0d83-b99d-1c5b0c744855@linux.ibm.com>
References: <20191025044721.16617-1-alastair@au1.ibm.com>
         <20191025044721.16617-10-alastair@au1.ibm.com>
         <3ba57ce6-9135-0d83-b99d-1c5b0c744855@linux.ibm.com>
Organization: IBM Australia
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On Fri, 2019-11-08 at 08:10 +0100, Frederic Barrat wrote:
> 
> Le 25/10/2019 à 06:47, Alastair D'Silva a écrit :
> > From: Alastair D'Silva <alastair@d-silva.org>
> > 
> > Enable OpenCAPI Storage Class Memory driver on bare metal
> > 
> > Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> > ---
> >   arch/powerpc/configs/powernv_defconfig | 4 ++++
> >   1 file changed, 4 insertions(+)
> > 
> > diff --git a/arch/powerpc/configs/powernv_defconfig
> > b/arch/powerpc/configs/powernv_defconfig
> > index 6658cceb928c..45c0eff94964 100644
> > --- a/arch/powerpc/configs/powernv_defconfig
> > +++ b/arch/powerpc/configs/powernv_defconfig
> > @@ -352,3 +352,7 @@ CONFIG_KVM_BOOK3S_64=m
> >   CONFIG_KVM_BOOK3S_64_HV=m
> >   CONFIG_VHOST_NET=m
> >   CONFIG_PRINTK_TIME=y
> > +CONFIG_OCXL_SCM=m
> > +CONFIG_DEV_DAX=y
> > +CONFIG_DEV_DAX_PMEM=y
> > +CONFIG_FS_DAX=y
> 
> If this really the intent or do we want to activate DAX only if 
> CONFIG_OCXL_SCM is enabled?
> 
>    Fred

We had a bit of a play around with reworking this the other day.

Putting them in as depends didn't make sense, as they are "soft"
dependancies - the driver works and you can do some things without DAX.

Adding them as selects was rejected as selecting symbols that can also
be manually select is discouraged.

We ended up going full circle and adding them back to the defconfig.

-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819