When the Compute Module 4 was released (see my CM4 review here), I asked the Pi Foundation engineers when we might be able to boot off NVMe storage, since it was trivially easy to use with the exposed PCIe x1 lane on the CM4 IO Board.
The initial response in October 2020 was "we'll see". Luckily, after more people started asking about it, beta support was added for direct NVMe boot just a couple weeks ago.
Ever since the Pi 2 model B went to a 4-core processor, disk IO has often been the primary bottleneck for my Pi projects.
You can use microSD cards, which aren't horrible, but... well, nevermind, they're pretty bad as a primary disk. Or you can plug in a USB 3.0 SSD and get decent speed, but you end up with a cabling mess and lose bandwidth and latency to a USB-to-SATA or USB-to-NVMe adapter.
The Pi 4 actually has an x1 PCI Express gen 2.0 lane, but the USB 3.0 controller chip populates that bus on the model B. The Compute Module 4, however doesn't presume anything—it exposes the PCIe lane directly to any card it plugs into.
And in the case of Oratek's TOFU, it's exposed through an M.2 slot, making this board the first one I've used that can accept native NVMe storage, directly under the Pi:
I didn't know it at the time, but my results testing the EDUP WiFi 6 card (which uses the Intel AX200 chipset) on the Raspberry Pi in December weren't accurate.
It doesn't get 1.34 gigabits of bandwidth with the Raspberry Pi Compute Module 4 like I stated in my December video, WiFi 6 on the Raspberry Pi CM4 makes it Fly!.
I'm very thorough in my benchmarking, and if there's ever a weird anomaly, I try everything I can to prove or disprove the result before sharing it with anyone.
In this case, since I was chomping at the bit to move on to testing a Rosewill 2.5 gigabit Ethernet card, I didn't spend as much time as I should have re-verifying my results.
I got this Rosewill RC-20001 PCIe 2.5 Gbps Network Adapter working on the Raspberry Pi Compute Module 4.
Right after I got the card working, though, I tested it in an external powered PCI Express riser, and that test released the card's magic smoke. Oops.
Here's a dramatic re-enactment that's actually pretty accurate to what it looked like in real life:
Luckily, buying a replacment wasn't too bad, since the card is less than $20. But to get it to work on my spiffy new ten gigabit network, I also had to buy a new SFP+ transceiver that was compatible with 1, 2.5, 5, and 10 Gbps data rates, and that cost $60!
January 1, 2021 Update: My 1.34 Gbps benchmark was flawed. See this GitHub issue and this updated blog post to learn more: WiFi 6 is not faster than Ethernet on the Raspberry Pi.
After buying three wireless cards, a new WiFi router, optimizing my process for cross-compiling the Linux kernel for the Raspberry Pi, installing Intel's WiFi firmware, and patching Intel's wireless driver to make it work on the Raspberry Pi, I benchmarked the EDUP Intel AX200 WiFi 6 PCIe card and got 1.34 Gbps of bandwidth between the Raspberry Pi and a new ASUS WiFi 6 router.
This is my story.
Out of the box, to conserve power, the new Raspberry Pi Compute Module 4 doesn't enable its built-in USB 2.0 ports.
You might notice that if you plug something into one of the USB 2 ports on the IO Board and don't see it using lsusb -t. In fact, you see nothing, by default, if you run lsusb -t.
To enable the USB 2.0 ports on the Compute Module 4, you need to edit the boot config file (/boot/config.txt) and add:
dtoverlay=dwc2,dr_mode=host
Then reboot the Pi. Now you should be able to use the built-in USB 2.0 ports!
The Raspberry Pi Compute Module 4 comes in two main flavors: one with built-in eMMC storage, and one without it. If you opt for a Compute Module 4 with built-in eMMC storage, and you want to write a new OS image to the Compute Module, or manually edit files on the boot volume, you can do that just the same as you would a microSD card—but you need to first make the eMMC storage mountable on another computer.
This blog post shows how to mount the eMMC storage on another computer (in my case a Mac, but the process is very similar on Linux), and then how to flash a new OS image to it.
In addition to the tutorial below, I published a video version of this post covering installation and usage of rpiboot for flashing the eMMC on Windows, Ubuntu, Raspberry Pi OS, or macOS:
The Raspberry Pi Compute Module 4 eschews a built-in USB 3.0 controller and exposes a 1x PCI Express lane.
The slightly older Raspberry Pi 4 model B could be hacked to get access to the PCIe lane (sacrificing the VL805 USB 3.0 controller chip in the process), but it was a bit of a delicate operation and only a few daring souls tried it.
Watch this video for more detail about my experience using these GPUs on the CM4:
GPUs on a Raspberry Pi Compute Module 4!
People have been overclocking Raspberry Pis since the beginning of time, and the Raspberry Pi 4 is no exception.
I wanted to see if the Compute Module 4 (see my full review here) could handle overclocking the same way, and how fast I could get mine to run without crashing.
There's a video version of this blog post, if you'd like to watch that instead:
Raspberry Pi Compute Module 4 OVERCLOCKED.
Six years ago, the Raspberry Pi Foundation introduced the Compute Module: a teensy-tiny version of the popular Raspberry Pi model B board.
Between then and now, there have been multiple revisions to the Compute Module, like the 3+ I used in my Raspberry Pi Cluster YouTube series, but they've all had the same basic form factor and a very limited feature set.
But today, that all changes with the fourth generation of the compute module, the Compute Module 4! Here's a size comparison with the previous-generation Compute Module 3+, some other common Pi models, and an SD and microSD card (remember when the original Pi used a full-size SD card?):