From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Chou Date: Tue, 29 Dec 2015 08:55:45 +0800 Subject: [U-Boot] [PATCH 3/7] arm: use generic dtb rule with CONFIG_DEFAULT_DEVICE_TREE In-Reply-To: References: <1451223875-20914-1-git-send-email-thomas@wytron.com.tw> <1451223875-20914-3-git-send-email-thomas@wytron.com.tw> Message-ID: <5681DA11.9030908@wytron.com.tw> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Simon, On 2015?12?29? 08:22, Simon Glass wrote: > Hi Thomas, > > On 27 December 2015 at 19:16, Bin Meng wrote: >> On Sun, Dec 27, 2015 at 9:44 PM, Thomas Chou wrote: >>> Use generic dtb rule with CONFIG_DEFAULT_DEVICE_TREE, so that >>> there is no need to list all the dtb for different targets/boards. >>> >>> Signed-off-by: Thomas Chou >>> Cc: Albert Aribaud >>> --- >>> arch/arm/dts/Makefile | 192 +------------------------------------------------- >>> 1 file changed, 1 insertion(+), 191 deletions(-) >>> >> >> Reviewed-by: Bin Meng > > The problem with these patches is that it prevents building all the > compatible device tree files for a board family. The default device > tree is just that - it is not the only one that can be used. A build > system can taken one of the output device tree files and package it > with U-Boot. If we don't build then, then that becomes impossible. > > What is the purpose of these patches? > > A better solution might be to add an option to list the files which > should be built. Then we gain control over this, if that is what you > are trying to achieve. The device tree describes hardware. Each board is a hardware, and should have only one device tree. The u-boot is a boot loader, which might have different options to load the next stage, eg. Linux. As I see in the configs/ dir, there can be several defconfig for a board and uses the same device tree. With device tree controlled u-boot, the output is u-boot-dtb.bin for each configuration. The next stage, say, Linux, gets device tree from u-boot. A single kernel can work on many different boards bond with possibly different device tree blob and booting configuration. We can use buildman to build a family of target binary including device tree blob. So I don't see the reason to keep the list of device tree per target. Best regards, Thomas