Author: Christof Meerwald

Tizen on Orange Pi PC

Made some significant progress for running Tizen on an Orange Pi PC (and hopefully any other SBC with a similar Mali GPU). Main issue was that alignments in TBM (Tizen Buffer Manager) weren't in sync with what the actual GPU driver expected. With that fixed, rendering seems to work fine now and I was also able to enable Full HD (1920x1080) resolution.

Next step would be to get the Home Screen app auto started and find some way to get a "Home" button (to be able to switch between apps without completely closing them).

SIGCHLD si_pid Linux kernel bug

While trying to get Tizen working on my Orange Pi PC, I noticed some strange behaviour in the Linux kernel in that SIGCHLD signals sent to the parent process don't always set the "si_pid" field correctly. I tracked this down to a bug in the Linux kernel for multithreaded process termination, see SIGCHLD signal sometimes sent with si_pid==0 (Linux 5.6.5). Luckily, a patch has already been posted less than 24 hours later.

Rock Pi S Review

Got a $20 voucher code for a review of a Rock Pi S SBC. Although the cost of the board is only $13.90, with shipping at just over $8, it's a bit over $22 in total. When the board arrived, I did actually wonder if shipping could have been made a bit more economical by not putting the tiny board into a huge box (175 mm x 115 mm x 95 mm) which had a plastic case (70 mm x 50 mm x 25 mm) with the board in it.

Anyway, two things to note about the board are that the serial console uses 1.5 Mbps (which is different to the more common 115200 bps used by other boards), and uses a USB Type C connector for power (like the Raspberry Pi 4, but unlike older SBCs).

Downloading the Ubuntu image and writing it to a SanDisk Ultra 16 GB MicroSD card seemed to work fine to get it to boot. One thing I did notice was that the SSH server keys seemed to have been written to the image and not regenerated on first boot. The other thing to be aware of is that the kernel being used is fairly old (4.4.143) with mainline kernel support only starting to appear now.

One thing that appears strange to me is that total memory is only shown as "MemTotal: 432280 kB" - I am not entirely sure what this isn't (much) closer to 512 MB.

Finally, power consumption seems to be quite good. With WiFi turned on, but otherwise completely idle, my USB tester shows the device using only around 0.2 W. Doing a "ping" and it will go up to around 0.36 W. Reading from the MicroSD card also uses around 0.4 W. Keeping all 4 cores of the CPU busy and power consumption goes up to around 0.85 W.

kmscube Running on Orange Pi PC with Mainline Kernel

Managed to get kmscube running on my Orange Pi PC with a mainline Linux 5.3 kernel and an updated mesa package from Ubuntu's ubuntu-x-swat PPA. The amazing thing is that it's all just mainline now, no board-specific patches needed. Interestingly, a Raspberry Pi 3 still needs a kernel built from its own branch to get that level of hardware support.

On a slightly related note I have been looking at what level of support I get for my ODROID-C1 now. Unfortunately, there is still no HDMI output and no USB OTG support. Interestingly, HDMI output does work on NetBSD.

ACME DNS Validation

I was looking at modifying acme tiny to support DNS-01 validation with a custom PowerDNS backend just a few days ago (in my case to get certificates for an XMPP server where there isn't a corresponding HTTP server or the HTTP server is hosted on a different machine). This work is available from Subversion: pdns-acme-backend.

Interestingly, I am just reading that Let's Encrypt is now supporting wildcard certificates that need to be validated using the DNS-01 challenge type.