From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Wed, 23 Jun 2021 07:19:04 +0200 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by lore.white.stw.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1lvvI0-0005Ih-Bj for lore@lore.pengutronix.de; Wed, 23 Jun 2021 07:19:04 +0200 Received: from bombadil.infradead.org ([2607:7c80:54:e::133]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lvvHy-0007l5-GR for lore@pengutronix.de; Wed, 23 Jun 2021 07:19:04 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Cc:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=H+TCvJwkThe/hQHF298ihzYFKURS6VA9WaWeiho27SI=; b=ML8lm8gxd64VqX SerJFwlEc0lJlnedoYuVWJ7ysu/odSoRSMxvmcZS7++/p6x1uJ9pwYJNO/2WVJ2OQmdl27FMCXw0V sfpKp65MQYjJnJAd8O8jjzUkeMfN4r5k37iD060b3g2wMgLP0kvh3TbqiCHjXcUcgacZydzArWFH7 LNmdgRvaRmnRDvmsWQKIcui2TfaicnngT0m/vowvMDdJY5Q6k6SiPPYm+oTsxdSAf8bW/zdAGCYty RuQIjXQY6/U10e5Mi7PBde+TvklwILTXnbwGgVzfkDjOkwHBB7bMfD+QLkAAPV6s7Ypva6Pa19PaP Euu3b6mTW+rZSz6zpB7w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1lvvGh-009N5I-Mq; Wed, 23 Jun 2021 05:17:43 +0000 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1lvvFl-009MUM-EQ for barebox@lists.infradead.org; Wed, 23 Jun 2021 05:16:47 +0000 Received: from dude02.hi.pengutronix.de ([2001:67c:670:100:1d::28]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lvvFc-0006rR-4j; Wed, 23 Jun 2021 07:16:36 +0200 Received: from sha by dude02.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1lvvFb-0000VY-0V; Wed, 23 Jun 2021 07:16:35 +0200 From: Sascha Hauer To: Barebox List Date: Wed, 23 Jun 2021 07:16:31 +0200 Message-Id: <20210623051632.30253-17-s.hauer@pengutronix.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210623051632.30253-1-s.hauer@pengutronix.de> References: <20210623051632.30253-1-s.hauer@pengutronix.de> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210622_221645_583886_98780648 X-CRM114-Status: GOOD ( 16.99 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:e::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.ext.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-4.8 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: [PATCH 16/17] Documentation: Add documentation for device tree overlays X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.ext.pengutronix.de) Document the recently gained device tree overlay features. Signed-off-by: Sascha Hauer --- Documentation/user/devicetree.rst | 37 +++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/Documentation/user/devicetree.rst b/Documentation/user/devicetree.rst index 4be6a1e703..d78394b7aa 100644 --- a/Documentation/user/devicetree.rst +++ b/Documentation/user/devicetree.rst @@ -75,3 +75,40 @@ It is important to know that these commands normally work on the internal devicetree. If you want to modify the devicetree the kernel is started with see the -f options to of_property and of_node. This option will register the operation for later execution on the Kernel devicetree. + +Device tree overlays +-------------------- + +barebox has support for device tree overlays. barebox knows two different trees, +the live tree and the device tree the kernel is started with. Both can be applied +overlays to. + +Device tree overlays on the live tree +..................................... + +While the live tree can be patched by board code, barebox does not +detect any changes to the live tree. To let the overlays have any effect, board +code must make sure the live tree is patched before the devices are instanciated +from it. + +Device tree overlays on the kernel device tree +.............................................. + +Overlays can be applied to the kernel device tree before it is handed over to +the kernel. The behaviour is controlled by different variables: + +``global.of_overlay_dir`` + Overlays are read from this directory. barebox will try to apply all overlays + found here if not limited by one of the other variables below. When using + bootloader spec this variable will be temporarily overwritten with + ``$mountpoint/overlays`` where ``$mountpoint`` is the path where the filesystem + containing the bootloader spec entries are located. +``global.of_overlay_compatible`` + This is a space separated list of compatibles. Only overlays matching one of + these compatibles will be applied. When this list is empty then all overlays + will be applied. Overlays that don't have a compatible are considered being + always compatible. +``global.of_overlay_filepattern`` + This is a space separated list of file patterns. An overlay is only applied + when its filename matches one of the patterns. The patterns can contain + ``*`` and ``?`` as wildcards. When empty, all files are applied. -- 2.29.2 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox