Hello.
The project that I'm current working on is about to upgrade kernel and userland of a recent ubuntu distro on the old samsung arm chromebook and enable kvm
This is the new tutorial that I'm following :
http://www.virtualopensystems.com/downloads/guides/kvm_on_chromebook/nv_u-boot-snow.kpart
Finally I have been able to compile kernel vers. 5.4.244 with all the kvm flags enabled and the exynos5250-snow.dtb file. Basically what I did has been :
cp nv_uboot-snow.kpart/linux-kvm-arm/u-boot/scripts
NB : I always use the file nv_uboot-snow.kpart I get from here :
sudo ./scripts/sdcard.sh /dev/sdX
mkdir ../mnt/
sudo mount /dev/sdX3 ../mnt/
sudo cp arch/arm/boot/my_uImage ../mnt/
sudo cp arch/arm/boot/dts/my_exynos5250-snow.dtb ../mnt/
sudo umount /dev/sdX3
sudo mount /dev/sdX4 mnt/
sudo cp -a ./here-it-needs-an-ubuntu-userland-compatible-with-the-kernel-5.4.244_which version ? /* mnt/
sudo umount /dev/sdX4
for building the userland,followed the section "Filesystems and booting the host" on the virtualopensystem tutorial
My compiled files worked. I'm also sure that I can even use a greater kernel version. My chromebook accepted them and it booted,but my screen became black some seconds after I saw it did.
The reason that caused the black screen is explained because by the fact that the nv-uboot that I've used is a simple-fb and according to :
https://chromium.googlesource.com/playground/chromium-org-site/+/refs/heads/main/chromium-os/firmware-porting-guide/using-nv-u-boot-on-the-samsung-arm-chromebook.md
nv-U-Boot with simplefb and simplified environment variablesIf all you want to do is use a simple nv-u-boot so you can get a firmware prompt and load a non-Chrome OS kernel, then it might be easier for you to use the “simplefb” U-boot. The two CLs for enabling this are: Here and here.There are a couple of things to keep in mind with it:It instantiates the ‘simplefb’ device in the kernel device-tree, so that a kernel with the corresponding driver (CONFIG_FB_SIMPLE) will configure and use itSince the framebuffer is kept alive from u-boot, it means that if you build your kernel with SYSMMU support, and use the regular FIMD graphics driver that Samsung provides, your system will crash on boot since the mapping that the simplefb is using will be invalidated when SYSMMU is enabled.The simplefb firmware (linked at the top of the page above) has most of the environment variables removed, to make it easier to see what is actually used to boot the system, and edit them accordingly.
the vanilla kernel conflicts with my nv-uboot unless I "clear the source of dtb from video devices".
This is what I've understood and what I should I do,but I don't know how to do it. Can someone of you point me to a good (focused,concise and not so much technical) tutorial that I can teach me how can I accomplish that task ? thanks.