From mboxrd@z Thu Jan 1 00:00:00 1970 From: swarren@wwwdotorg.org (Stephen Warren) Date: Wed, 08 Aug 2012 11:50:49 -0600 Subject: Kernels on Bad Firmware (was Re: kernel entry for thumb2-only cpus) In-Reply-To: References: Message-ID: <5022A6F9.2000206@wwwdotorg.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 08/08/2012 11:36 AM, Matt Sealey wrote: ... > The fact we could update it with a script was the awesome thing about > using OpenFirmware - > but U-Boot can do this too, since libfdt is there and it's one option > to enable it to allow script > based modification of the blob. If the DT is hardcoded into the firmware somehow > (CONFIG_OF_CONTROL I think) then platforms can load "boot.scr" from > the root filesystem ... Just a comment on CONFIG_OF_CONTROL... In U-Boot, CONFIG_OF_CONTROL determines whether U-Boot uses a device tree to configure itself. This is completely orthogonal to whether a device tree is passed to the kernel, and where the kernel DT comes from, which is still controlled by the bootm/bootz command parameters. The DT used to configure U-Boot isn't the same one passed to the kernel typically. The one for U-Boot is typically appended to the U-Boot image, whereas the one passed to the kernel is likely loaded from a file in /boot alongside the uImage/zImage of the kernel. I suppose the U-Boot script /could/ be written to encode the location of the appended DTB used by U-Boot and so pass the same one to the kernel, I don't believe anyone has done that. Besides, U-Boot's copy of the .dts files has diverged a little from the kernel's...:-(