I have a Debian Stretch mender image, created with mender-convert 2.5.0. Its on a pi 3B, and the primary partition boots correctly and console output is displayed via HDMI. I then successfully installed a Debian Buster artifact to the secondary partition via standalone mender client.
The problem is that when the secondary partition boots, there is no HDMI output…just the rainbow screen. However the partition does completely boot up, as I can access it via SSH. In the hope of enabling HDMI output, I have been experimenting with the HDMI related settings in
/uboot/config.txt. Unfortunately, none of those enable the HDMI.
For comparison, I mender converted a clean Buster image. So in this case Buster is running from the primary partition and there is nothing on the secondary. This image boots up and successfully outputs to HDMI. I then compared startup messages in the kernel logs between the two images, and thought I had found a smoking gun. The Buster image that correctly outputs to HDMI had the following in its kernel command line:
This entry did not exist in the command line for the rainbow screen image. So I added it to cmdline.txt and rebooted. Unfortunately, it did not enable HDMI output.
What else is there to look for with this issue? The artifact installed on the secondary partition does not output to HDMI, but the full system image created with mender-convert will correctly show output on HDMI. Is there some other HDMI or console related setting in U-Boot to get past this?
For reference, here is the full kernel command line parameters for both cases.
HDMI output, running from primary partition:
Aug 5 17:31:35 raspberrypi kernel: [ 0.000000] Kernel command line: coherent_pool=1M 8250.nr_uarts=1 snd_bcm2835.enable_compat_alsa=0 snd_bcm2835.enable_hdmi=1 bcm2708_fb.fbwidth=1824 bcm2708_fb.fbheight=984 bcm2708_fb.fbswap=1 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000 console=ttyS0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 fsck.repair=yes rootwait
No HDMI output, installed via artifact to secondary partition:
Jul 23 03:07:44 im3-rack1 kernel: [ 0.000000] Kernel command line: 8250.nr_uarts=1 bcm2708_fb.fbwidth=1824 bcm2708_fb.fbheight=984 bcm2708_fb.fbswap=1 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000 dwc_otg.lpm_enable=0 console=ttyS0,115200 console=tty1 root=/dev/mmcblk0p3 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait