How u-boot can chain "grub" and booting a mainline kernel on my ARM Chromebook

[Mario Marietto]

Some days ago I successfully compiled the kernel version. 5.4.244 with all
the kvm flags enabled and the exynos 5250-snow.dtb file.

On Sat, Jul 1, 2023 at 2:46 PM Peter Robinson <pbrobinson at gmail.com> wrote:

> On Sat, Jul 1, 2023 at 1:40 PM Mario Marietto <marietto2008 at gmail.com>
> wrote:
> >
> > Excuse me. The problem is not the kernel version that I'm running,but
> how to use the unverified u-boot created by virtual open systems to
> chainload the kernel of whatever used to boot one recent ISO image created
> by hexdump0815. Because it contains the code to put the chromebook in
> hypervisor mode. Without that special u-boot version,I can for sure install
> one ISO image of hexdump0815 (I've chosen jammy as an example,but
> hexdump0815 created some more updated isos),but KVM will not be enabled.
>
> You'll note I didn't comment on the U-Boot piece, but my point still
> remains, that KVM for a 32 bit Arm host was removed in the 5.7 kernel
> upstream, so even when you sort out the other problem you still won't
> have virt due to the kernel.
>
> > On Sat, Jul 1, 2023 at 2:34 PM Peter Robinson <pbrobinson at gmail.com>
> wrote:
> >>
> >> On Sat, Jul 1, 2023 at 1:25 PM Mario Marietto <marietto2008 at gmail.com>
> wrote:
> >> >
> >> > Hello.
> >> >
> >> > I would like to enable KVM virtualization on my old ARM Chromebook
> >> > laptop,based on the Exynos5250 arm 32 bit cpu aka snow,model xe303c12.
> >>
> >> Upstream Linux kernel dropped support for running virt on 32 bit hosts
> >> (you can still run a 32 bit guest on a 64 bit host) in the upstream
> >> linux kernel with the 5.7 release (May 31st, 2020) so you'll probably
> >> have to run a 5.4.x LTS kernel rather than 5.18.x (not sure why you
> >> chose that one) at the very least.
> >>
> >> > The first thing I did has been to dd the image below directly on the
> sd
> >> > card :
> >> >
> >> >
> https://github.com/hexdump0815/imagebuilder/releases/download/220619-01/chromebook_snow-armv7l-jammy.img.gz
> >> >
> >> > and it worked like a charm,but kvm was disabled. So,I have started to
> look
> >> > for a good documentation to understand how to enable kvm and I found
> this :
> >> >
> >> >
> http://www.virtualopensystems.com/en/solutions/guides/kvm-on-chromebook/
> >> >
> >> > I've followed all the instructions and it worked,but only with Ubuntu
> 13.04
> >> > and 14.04. More upgraded ubuntu versions give a lot of problems and
> they
> >> > don't work.
> >> >
> >> > So,I've thought about a fresh idea. What about to install the virtual
> open
> >> > systems "non-verified u-boot" on the first partition like explained
> in the
> >> > tutorial,and,instead of starting another u-boot after the
> original,can I
> >> > chain grub with the kernel installed for example by the ubuntu jammy
> iso
> >> > image created by "hexdump0815" ? To be honest I'm not sure if
> hexdump0815
> >> > used grub,but I will explain this later.
> >> >
> >> > Anyway,I've got the idea by reading here :
> >> >
> >> >
> https://unix.stackexchange.com/questions/599141/how-to-install-grub-bootloader-as-second-stage-bootloader
> >> > So,now,I'm going to explain what's the content of the partitions on my
> >> > Frankenstein sd card.
> >> >
> >> > 1) /dev/sdh1 = unknown = 16 MB. I've created this partition by doing :
> >> >
> >> > $ sudo dd if=nv_uboot-snow.kpart of=/dev/sdh1
> >> >
> >> > Where I've got the file nv_uboot-snow.kpart ? From here :
> >> >
> >> >
> http://www.virtualopensystems.com/downloads/guides/kvm_on_chromebook/nv_u-boot-snow.kpart
> >> >
> >> > 2) /dev/sdh2 = unknown = 16 MB. This partition has been created by
> >> > executing the following
> >> >
> >> > script :
> >> >
> >> > $ sudo ./scripts/sdcard.sh /dev/sdh
> >> >
> >> > 3) /dev/sdh3 = ext2 BOOT.
> >> >
> >> > Inside the partition /dev/sdh3 I have copied the following files and
> >> > folders (taken
> >> > from the hexdump0815 "chromebook_snow-armv7l-jammy.img.gz" file :
> >> >
> >> > a) dtb-5.18.1-stb-cbe+ = directory
> >> > b) extlinux = directory
> >> > c) extra = directory
> >> >
> >> > d) config.5.18.1-stb-cbe+ : file
> >> > e) initrd.img-5.18.1-stb-cbe+ : file
> >> > f) System.map-5.18.1-stb-cbe+ : file
> >> > g) vmlinux.kpart-5.18.1-stb-cbe+ : file
> >> > h) zImage-5.18.1-stb.cbe+ : file
> >> >
> >> > Inside the directory "dtb-5.18.1-stb-cbe+" there are the following
> files :
> >> >
> >> > a) exynos5250-snow.dtb
> >> > b) exynos5250-snow-rev5.dtb
> >> > c) exynos5250-spring.dtb
> >> >
> >> > Inside the directory "extlinux",there is the following file :
> >> >
> >> > a) extlinux.conf : that has the following content :
> >> >
> >> > TIMEOUT 30
> >> >
> >> > DEFAULT linux-snow-rev4
> >> >
> >> > MENU TITLE snow chromebook boot options
> >> >
> >> > # rev4 snow chromebook
> >> > LABEL linux-snow-rev4
> >> >       MENU LABEL linux rev4 snow
> >> >       LINUX ../zImage-5.18.1-stb-cbe+
> >> >       INITRD ../initrd.img-5.18.1-stb-cbe+
> >> >       FDT ../dtb-5.18.1-stb-cbe+/exynos5250-snow.dtb
> >> >       APPEND console=tty1 root=LABEL=rootpart ro rootwait
> net.ifnames=0
> >> > ipv6.disable=1 fsck.repair=yes noresume
> >> >
> >> > # rev5 snow chromebook
> >> > LABEL linux-snow-rev5
> >> >       MENU LABEL linux rev5 snow
> >> >       LINUX ../zImage-5.18.1-stb-cbe+
> >> >       INITRD ../initrd.img-5.18.1-stb-cbe+
> >> >       FDT ../dtb-5.18.1-stb-cbe+/exynos5250-snow-rev5.dtb
> >> >       APPEND console=tty1 root=LABEL=rootpart ro rootwait
> net.ifnames=0
> >> > ipv6.disable=1 fsck.repair=yes noresume
> >> >
> >> > # spring chromebook - untested
> >> > LABEL linux-spring
> >> >       MENU LABEL linux spring
> >> >       LINUX ../zImage-5.18.1-stb-cbe+
> >> >       INITRD ../initrd.img-5.18.1-stb-cbe+
> >> >       # rev4 snow chromebook
> >> >       FDT ../dtb-5.18.1-stb-cbe+/exynos5250-spring.dtb
> >> >       APPEND console=tty1 root=LABEL=rootpart ro rootwait
> net.ifnames=0
> >> > ipv6.disable=1 fsck.repair=yes noresume
> >> >
> >> > Inside the extra directory there are the following files :
> >> >
> >> > a) kernel-chromebook_snow-legacy.tar.gz
> >> > b) uboot.kpart.cbe-snow
> >> > c) uboot.kpart.cbe-snow-alternative
> >> > d) uboot.kpart.cbe-spring
> >> >
> >> > 4) /dev/sdh4 : inside here I have copied all the files of the jammy
> >> > userland prepared by hexdump0818.
> >> >
> >> > That's all. What I want to do is if and how can I chainload the
> >> > "non-verified u-boot"
> >> > that is installed on the partition /dev/sdh1 with grub or whatever
> >> > mechanism it is able to boot the hexdump0815 jammy iso image.
> >> >
> >> > As I repeat,the "non-verified u-boot" is produced by the script called
> >> > "build.sh",that's stored inside the u-boot/scripts directory. And if
> what I
> >> > want to do is impossible,can you explain to me how I can enable kvm
> on my
> >> > chromebook arm,using the most recent kernel possible ? I already know
> that
> >> > the support for kvm on arm 32 has been dropped on kernel 5.7,but for
> me to
> >> > use a lower kernel than 5.7 is ok. I've been working on this project
> for a
> >> > lot of months. I would like to see some progress. Thanks.
> >> >
> >> > --
> >> > Mario.
> >
> >
> >
> > --
> > Mario.
>


-- 
Mario.