Hi Adam, On 08/11/2015 04:31 PM, Adam Rossi wrote:
Howdy folks. I have had a devil of a time creating my own machine.conf and getting it to boot, so I went back to using the stock beaglebone.conf machine. I need to modify the DTB file that my prototype loads, so I decompiled the yocto am335x-boneblack.dtb, added some special sauce to the dts, and added the following to a linux-yocto_3.19.bbappend recipe:FILESEXTRAPATHS_prepend := "${THISDIR}/files:" SRC_URI +="file://touchscreen.cfg \ file://special-am335x-boneblack.dts" do_install_prepend() { cp ${WORKDIR}/special-am335x-boneblack.dts ${S}/arch/${ARCH}/boot/dts/ } KERNEL_DEVICETREE_beaglebone = "special-am335x-boneblack.dtb" This works, I get a special-am335x-boneblack.dtb in my image. However, on booting the files on my beagle bone, I get an error that the system cannot find the boot/am335x-boneblack.dtb file. Creating a symlink to my special-am335x-boneblack.dtb solves the problem. Where does the system configure the directions to look for "am335x-boneblack.dtb"? I suspect this is because the stock beaglebone.conf file also has a KERNEL_DEVICETREE="am335x-boneblack.dtb". Perhaps my kernel recipe is only partly overriding this? Thanks for your continuing help. Regards, Adam
The only component responsible for looking the DTB during boot is the bootloader (usually U-Boot). If you break the boot sequence and type "printenv", you can look at the contents of "bootcmd" variable and see which other scripts/vars it uses, in order to see how the bootloader tries to load the DT. If/when you do some modifications to the default U-Boot environment, you can generate a patch to your U-Boot source code and add this patch to your machine-specific U-Boot, so you can have the changes integrated in your next system build. Regards, Nikolay -- _______________________________________________ yocto mailing list yocto@yoctoproject.org https://lists.yoctoproject.org/listinfo/yocto
