Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 14 Dec 2022 15:27:51 -0800
From:   Dan Williams <dan.j.williams@intel.com>
To:     Luis Chamberlain <mcgrof@kernel.org>, <masahiroy@kernel.org>,
        <nathan@kernel.org>, <ndesaulniers@google.com>,
        <nicolas@fjasle.eu>, <linux-kbuild@vger.kernel.org>,
        <alison.schofield@intel.com>, <dan.j.williams@intel.com>
CC:     <dave@stgolabs.net>, <a.manzanares@samsung.com>,
        <mcgrof@kernel.org>, <lucas.de.marchi@gmail.com>,
        <linux-cxl@vger.kernel.org>, <linux-modules@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] kbuild: Modify default INSTALL_MOD_DIR from extra to
 updates
Message-ID: <639a5bf779bad_b05d1294ee@dwillia2-xfh.jf.intel.com.notmuch>
References: <20221214231718.1002194-1-mcgrof@kernel.org>
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <20221214231718.1002194-1-mcgrof@kernel.org>
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?twJoLNqjUMIOBl+rdp3tb5ZAeTS5D0JvLRYLjqruDKFCgvHk4+ck2fJEV4kB?=
 =?us-ascii?Q?mIX9lsRoJtGhE5fA8OPDZOUuvGqZuil1rGnGcNIZ1YBe+gdXLjOcU2fD58H8?=
 =?us-ascii?Q?/ZWTHdb+C1Qvos0/4za9IoX/o7SCjTD7NGhd2dLZ+OHbPQVHC9sVbxfDRuU6?=
 =?us-ascii?Q?nJRbDbYQ1Vzaza1WZfODnyZoierKymYJOdI0IYwlu+jSFViol7v6tpshXTm/?=
 =?us-ascii?Q?OPyezQaTEDQmuktb9jaxcZrmme6qvVXddk+tF1v1mauKfZVNStHbJ2NSCs+G?=
 =?us-ascii?Q?6bZB7AAvXuo3VG9NeKbXc8bUCGCp9f8r8ROLU1FlxDcDgQcI3mf2dngtYEKM?=
 =?us-ascii?Q?WthBA7zTqL0gRdL5lshlMx6W83Kv3PN+4cnmwgLoXcGepeo/vY+U+v2uhpq0?=
 =?us-ascii?Q?ZtZ/0wo/opu0FSi/jSW7OIksmJiZMd1Jrg6y9v41ICQVhq9bxmrqOM2Q+kr7?=
 =?us-ascii?Q?vmZ+WQo89Dbh2Ne+IzyTu5tUlqoBTcu/VW4GG7UfdkHwwlSO495QlJ1HtA4R?=
 =?us-ascii?Q?eu9fP41XDezgTzMQPgRoXylHjI2UYgkg+2vmVp7qyQnYq1pUXZv/E+CFx2nJ?=
 =?us-ascii?Q?TgSImCpdBloN+FdqWqifh8mb5hMXm1TmgkrU/DYd+LbldX8fqoVsoTL5kqR3?=
 =?us-ascii?Q?nS3GFFBFa0+f8q0vSbYfwd63Q+MefezXLpXXSoqnVTEmiEmOO9d6ZZ/EvU/Q?=
 =?us-ascii?Q?efUn798sEhds+D3DnfXU7+igFaYmTduDB/pt0cJp5K/SA4aKqqbZF/Tlw4/3?=
 =?us-ascii?Q?9Gg4Md8bRTrfH8IgliQ76lHJC2cxu0KF965R/qgVNd1pi7WN+/3+Y1P3g8D5?=
 =?us-ascii?Q?sJmWUY1kz52rpkUuXv+C8MEvn51P/zd2nS5mgLnvdgrcYiGIUp+uawHV9/vL?=
 =?us-ascii?Q?jYbOCGF/fLYzy/YSgGjuXrDNDhKQD3Oa9lAGbwFkQfDsBjUoXSYSgCAGMvZG?=
 =?us-ascii?Q?jwNetZgptWDFmtqXqyYndtzKETF8yN9LfedznGt7b8Husp4sARdiEA0gn3Gu?=
 =?us-ascii?Q?3W46Bvi2GQVz05kjyfcQMYqf6cHlQiO16Od8nprNCwjfiBd+MR43NXZ7jUIk?=
 =?us-ascii?Q?9EgN7kJgjduZAvh2CenqM9L7tr7zAHuLVS0PIGS/0KaBcaxAUfwbL4o1H5Mf?=
 =?us-ascii?Q?yYQhjwGuRtHF3psaNRLKhEUh/TqYdHnp5LN/3pahUNFzq6pZxfa6/h2AFYGG?=
 =?us-ascii?Q?YfSl5WizYALkxiOS+5YQBwWLdhPXjJWxGWrGBcxZ8TXa1XDa/lOnG864uotC?=
 =?us-ascii?Q?QZL9S+vJpV0cHZrkn54mbDnvU0Z/+XQdAvEpfJmlI4S9z5StaoEg5UtPRHLk?=
 =?us-ascii?Q?jp/w6oVonbBYi57HO8yRaO0NRHwk1uum+Jk3HdBrN92fBeRO163OjWu+zeaJ?=
 =?us-ascii?Q?GUNUuXfwtwDg3kjaTtA1W6lA/LhxCxjgOeSho+iJgmsZVSqQdKFE3s1bnK8L?=
 =?us-ascii?Q?5ak4/FUhicsQSfa4h8YnokpuRCZ5Xs5oz/6+vShnCyoWvSiQiOl3D3MYi+Qy?=
 =?us-ascii?Q?QYSsp4p1URmv4b8o3t2sekgfSQhiYwbY+tyF9b2uYhdvH4yMQK7vdQpF2IXx?=
 =?us-ascii?Q?+iRZ8pHEdSsgvXkoA5wFEsCudI3OErLbqWIAyRFHTh63qHWDTS4rZsP/IhBf?=
 =?us-ascii?Q?Sg=3D=3D?=
X-MS-Exchange-CrossTenant-Network-Message-Id: 1feefd96-377a-45b4-895e-08dade2ad341
X-MS-Exchange-CrossTenant-AuthSource: MWHPR1101MB2126.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Dec 2022 23:27:54.2189
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: T4+R4erQWGDQtKQQ3CM/sm11Naa/UGwzMixXR4SDkEtR8HhT6dsUATpOmw69GcRGpZizXEBtUX9RCLeDcP46XzikkwXMUHq+K/3urxZUso4=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR11MB6797
X-OriginatorOrg: intel.com
X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,
        SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Luis Chamberlain wrote:
> The default INSTALL_MOD_DIR of using the /lib/modules/$(uname -r)/extra
> directory for external modules assumes distributions will have something
> like  /etc/depmod.d/dist.conf with:
> 
> search updates extra built-in
> 
> However, only some Red Hat release have and use the extra stuff for
> years now. Meanwhile, the depmod.c tool in kmod has *forever* used
> the "updates" directory as part of the search path by default *if*
> your distribution does not have any depmod.d configuration.
> 
> If you compile and install an external module today, even upstream
> kernel mock drivers (tools/testing/cxl) the modules_install target
> will pick up the new drivers but will not allow override of drivers
> from updates to override built-in ones.
> 
> Since module-init-tools was deprecated over 11 years ago and now kmod
> has since its inception used the "updates" directory as part of its
> default search path to allow overrides, and since the "extra" stuff
> was in practice only used by Red Hat stuff, use the more distro
> agnostic override path "updates" to allow external modules to
> also override proper production kernel modules.
> 
> This would allow mocking drivers tools to not have to muck with
> depmod.d config files or assume that your distro will have extra
> on a configuration file over built-in.
> 
> With today's default you end up actually *crashing* Linux when
> trying to load cxl_test with the default "extra" [0] directory being
> used. This fixes that and allows other mocking drivers to do
> less work.
> 
> [0] https://lkml.kernel.org/r/20221209062919.1096779-1-mcgrof@kernel.org
> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

Thanks for digging into the history here Luis!

Acked-by: Dan Williams <dan.j.williams@intel.com>