CentOS Userland armv7hl on the ODROID-HC2
Table of Contents
The following post is heavily based on Fedora on the ODROID-HC2
It is is about installing CentOS Userland armv7hl on an ODROID-HC2 (from a Fedora 31 x86_64 workstation).
The aim is to get the ODROID in a state where one can ssh as root to the host.
Both initial setup over serial and installing without using a serial console are described.
Ansible and further uses will be described in separate posts.
Note on Other OS Images
Images for the ODROID-XU4 are fully compatible with the HC2 (source: manual from Pollin, the German shop I bought mine from). So you are definitely not limited to running Fedora on the ODROID-HC2 Single Board Computer (SBC).
NOTE
These are not the official install steps, those are here and you should read them!
Overview of Steps
- install needed software
- obtain CentOS Userland for armv7hl
- write CentOS Userland image with
fedora-arm-image-installer - FIXME fuse signed blobs from ODROID into SD card
- FIXME symlink for uboot
- boot ODROD-HC2 from prepared card
Install Needed Software
On your workstation
sudo dnf install arm-image-installer uboot-images-armv7
I used
- arm-image-installer-2.13-2.fc31.noarch
- uboot-images-armv7-2019.10-2.fc31.noarch
Download Fedora for ARMv7
Get the armhfp image CentOS-Userland-7-armv7hl-generic-Minimal-1908-sda.raw.xz I chose the generic Minimal version (and it’s checksum file) since I plan to add what’s missing with Ansible.
Verify the file with
On your workstation
sha256sum -c sha256sum.txt
Write CentOS7 Image to µSD card
Attach a µSD card to your workstation and check with lsblk what the name is.
In the following examples I’ll be using /dev/sdi.
Change to the directory where you downloaded the Minimal image for ARM Servers.
Obviously adjust the path to your ssh pubkey.
Also I immediately inject my ssh key.
For initial bringup, I’ll be using --norootpass.
On your workstation
sudo fedora-arm-image-installer \
--target=none \
--image=CentOS-Userland-7-armv7hl-generic-Minimal-1908-sda.raw.xz \
--addkey=/home/pcfe/.ssh/id_USBkey.pub \
--norootpass \
--resizefs \
--args "console=ttySAC2,115200n8 cpuidle.off=1 rd.driver.pre=ledtrig-heartbeat,xhci-plat-hcd no_bL_switcher" \
--media=/dev/sdi
FIXME: resizefs resized the partition but not the filesystem!
If you use --resizefs, the whole remaining space on your µSD card should be used to grow /.
Alternatively you can drop that parameter and comfortably resize partition 3 on the card
on your linux workstation with gnome-disks.
Remember to re-plug the card if told to do so by a script.
[root@odroid-hc2-00 ~]# /usr/bin/rootfs-expand [1/1]
/dev/mmcblk1p4 /dev/mmcblk1 4
Extending partition 4 to max size ....
NOCHANGE: partition 4 could only be grown by -33 [fudge=2048]
Resizing ext4 filesystem ...
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/mmcblk1p4 is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 4
The filesystem on /dev/mmcblk1p4 is now 7487616 blocks long.
Done.
/dev/mmcblk1p4 29G 1.3G 27G 5% /
Comments on the Used kernel cmdline Parameters
FIXME, these all need verifying.
Fuse SD card
Why this is needed is well explained in the following two
- U-Boot’s README.odroid
- The post [fedora-arm] Fedora 27 on ODroid UX4 in the Discussions about the Fedora ARM Project
Preparation; download signed blobs and tool
A big thank you to Chris for this blogpost. That gives straightforward commands one can copypasta.
Download the required files from Hardkernel.
On your workstation
mkdir hardkernel ; cd hardkernel
wget https://raw.githubusercontent.com/hardkernel/u-boot/odroidxu4-v2017.05/sd_fuse/sd_fusing.sh \
https://raw.githubusercontent.com/hardkernel/u-boot/odroidxu4-v2017.05/sd_fuse/bl1.bin.hardkernel \
https://raw.githubusercontent.com/hardkernel/u-boot/odroidxu4-v2017.05/sd_fuse/bl2.bin.hardkernel.720k_uboot \
https://raw.githubusercontent.com/hardkernel/u-boot/odroidxu4-v2017.05/sd_fuse/tzsw.bin.hardkernel
chmod a+x sd_fusing.sh
Use U-Boot files provided by Fedora (since they are more modern)
Copy the Fedora U-Boot files into the local dir.
On your workstation
cp /usr/share/uboot/odroid-xu3/u-boot.bin .
Fuse your SD card
Finally, run the fusing script to embed the files onto the SD card, passing in the device for your SD card.
On your workstation
sudo ./sd_fusing.sh /dev/sdi
Again, be sure to write to the correct device (my setup uses /dev/sdi)
It should end with
[...]
U-boot image is fused successfully.
Eject /dev/sdi and insert it again.
Do as instructed, re-plug the µSD card.
Mount partition 3 of the card (/), for the next steps.
Symlink for uboot
FIXME: odd, this is fixed in Fedora
FIXME: as root on your Workstation:
pushd /run/media/pcfe/__boot/dtb-4.19.72-300.el7.armv7hl/
ln -s exynos5422-odroidxu4.dtb exynos5422-odroid.dtb
popd
Fix for heartbeat LED
FIXME: double check if this f29 adjustment works on el7.
When Dracut makes the initramfs, it must find
instructions to load ledtrig-heartbeat, in addition to the rd.driver.pre=ledtrig-heartbeat
Create the file while you have / mounted anyway
On your workstation, as root
cat <<EOF >/run/media/pcfe/__/etc/dracut.conf.d/ledtrig-heartbeat.conf
add_drivers+=" ledtrig-heartbeat "
EOF
Do not forget to umount the card
unmount all partitions from the µSD card, remove from your workstation, insert into ODROID. Do not apply power yet.
Boot
Transfer card to ODROID-HC2 (not powered, all LEDs off) and apply power to boot.
Expect it to
- grab an IP via DHCP
- respond to ping after less than a minute
- respond to
ssh -v root@<IP>after less than two minutes
If these do not happen you will want to connect a serial console.
Enable heartbeat LED for kernel from image
Either re-do the initramfs once your ODROID has booted or just wait for dracut to automatically trigger on a kernel update.
On the ODROID, as root
dracut --force --verbose
On next reboot your heartbeat LED should be working.
You can enable it for the current boot by loading the module.
modprobe ledtrig-heartbeat
To Fix
FIXME: grub uses rhgb and quiet, remove those
[root@odroid-hc2-00 ~]# vim /boot/extlinux/extlinux.conf
Enable EPEL
Proceed as per https://wiki.centos.org/SpecialInterestGroup/AltArch/armhfp
All done
You should now be able to log in via ssh to your ODROID-HC2 running CentOS 7 Userland for armv7hl.