[yocto] custom linux kernel recipe

[Bruce Ashfield]

On 2016-08-29 07:34 AM, Mircea Gliga wrote:
> Hi
>
> I'm using krogoth and trying to create a qemu arm machine with the
> latest stable kernel 4.7.2.
> I created a recipe,recipes-kernel/linux/linux-stable_4.7.bb, in my layer
> with the following contents:
>
> ---
> inherit kernel
> require recipes-kernel/linux/linux-yocto.inc
>
> FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}-${PV}:"
>
> KBRANCH ?= "linux-4.7.y"
>
> SRCREV ?= "84fae3f89282ce86a0c0da30e35fe66dbcadda6f"
>
> KBRANCH_sama5d4-xplained ?= "linux-4.7.y"
> SRCREV_machine_sama5d4-xplained ?=
> "84fae3f89282ce86a0c0da30e35fe66dbcadda6f"
>
> KERNEL_DEVICETREE_sama5d4-xplained = "at91-sama5d4_xplained.dtb"
>
> KBRANCH_qemuarm ?= "linux-4.7.y"
>
> SRC_URI =
> "git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git;bareclone=1;branch=${KBRANCH}"
>
>
> SRC_URI += "file://defconfig"
>
> LINUX_VERSION = "4.7.2"
> PV = "${LINUX_VERSION}+git${SRCPV}"
>
> COMPATIBLE_MACHINE = "sama5d4-xplained|qemuarm"
> ---
>
> As you can see, I'm planning to use this recipe for multiple machines.
>
> In the recipes-kernel/linux/linux-stable-4.7/qemuarm/ directory I copied
> the defconfig file.
> I've created this defconfig file by:
> * sourcing my build environment, from my build directory: source
> build-qemu/tmp/environment-setup-armv5e-poky-linux-gnueabi
> * running "make vexpress_defconfig" in the kernel build directory. (I've
> used this tutorial
> https://balau82.wordpress.com/2012/03/31/compile-linux-kernel-3-2-for-arm-and-emulate-with-qemu/
> )
> This outputed:
>
> ---
> $ make vexpress_defconfig
>   GEN     ./Makefile
> #
> # configuration written to .config
> #
> ---
>
> * renamed .config to defconfig and then copy it in
> recipes-kernel/linux/linux-stable-4.7/qemuarm/
>
> In my local.conf I've added, in order to use my custom kernel for the
> qemu machine:
>
> ---
> MACHINE ??= "qemuarm"
> PREFERRED_PROVIDER_virtual/kernel_qemuarm ?= "linux-stable"
> ---
>
> Everything builds without errors (bitbake linux-stable), but when I
> start qemu (runqemu qemuarm) I only get a black screen in the QEMU window.
> This is the output of $ runqemu qemuarm:
> ---
> Continuing with the following parameters:
> KERNEL:
> [/home/user/yocto-k/build-qemu/tmp/deploy/images/qemuarm/zImage-qemuarm.bin]
>
> ROOTFS:
> [/home/user/yocto-k/build-qemu/tmp/deploy/images/qemuarm/custom-minimal-image-qemuarm-20160823102657.rootfs.ext4]
>
> FSTYPE: [ext4]
> Setting up tap interface under sudo
> [sudo] password for user:
> Acquiring lockfile for tap0...
> Running qemu-system-arm...
> /home/user/yocto-k/build-qemu/tmp/sysroots/x86_64-linux/usr/bin/qemu-system-arm
> -kernel
> /home/user/yocto-k/build-qemu/tmp/deploy/images/qemuarm/zImage-qemuarm.bin
> -net nic,model=virtio -net
> tap,vlan=0,ifname=tap0,script=no,downscript=no -M versatilepb -drive
> file=/home/user/yocto-k/build-qemu/tmp/deploy/images/qemuarm/custom-minimal-image-qemuarm-20160823102657.rootfs.ext4,if=virtio,format=raw
> -no-reboot -show-cursor -usb -usbdevice tablet -no-reboot -m 128 -serial
> mon:vc -serial null -append "root=/dev/vda rw console=ttyAMA0,115200
> console=tty ip=192.168.7.2::192.168.7.1:255.255.255.0 mem=128M
> highres=off rootfstype=ext4 "
> ---
>
> This is my build configuration:
> Build Configuration:
> BB_VERSION        = "1.30.0"
> BUILD_SYS         = "x86_64-linux"
> NATIVELSBSTRING   = "universal"
> TARGET_SYS        = "arm-poky-linux-gnueabi"
> MACHINE           = "qemuarm"
> DISTRO            = "poky"
> DISTRO_VERSION    = "2.1.1"
> TUNE_FEATURES     = "arm armv5 thumb dsp"
> TARGET_FPU        = "soft"
> meta
> meta-poky
> meta-yocto-bsp    = "krogoth:12eb72ee3b02f826a156ff4e396c770f2b93571e"
> meta-smartcom     = "master:121dbfb9f416de8442bbad1dc150271fd50b38e6"
> meta-atmel        = "krogoth:01ff01073dd8fa1463b7841fb0a8caa44559acdd"
> meta-oe
> meta-networking
> meta-python       = "krogoth:247b1267bbe95719cd4877d2d3cfbaf2a2f4865a"
>
>
> When I use the default linux-yocto as the preferred kernel (v 4.4)
> everything works as expected.
> Do you have any suggestions? Is there a problem with the defconfig file
> provided ?
> What is the proper way of creating this defconfig file for qemuarm ?
> I also tried using the .config file created when building
> linux-yocto_4.4 but got the same result.
> I tried the defconfig used for the

You need a variant of the patch I'm going to submit later today:

http://git.yoctoproject.org/cgit/cgit.cgi/poky-contrib/commit/?h=zedd/kernel&id=0fe665e69983fe9ef38319deedcb78ecd7b165cf

I'm about to bump linux-yocto to 4.8, which ran into the device tree
changes for the versatile/vexpress class boards. You are seeing the
same thing.


Bruce


>
> Thanks !
>