Biggest change here is that your Pi will now boot at the default (Pi Foundation-recommended) frequency, instead of the 600MHz minimum. One less configuration option to change on every upgrade!
IMPORTANT: HTTP(S) boot, like PXE and iSCSI, will not currently work with the internal network card, because the GENET driver has not been upstreamed yet. This means you need a supported USB interface (Ax88772b) to use this feature.
Our UEFI firmware already supports certain USB-based network adapters for network booting (or other purposes), but that requires an additional adapter, which becomes even more awkward if you want to use a PoE HAT. NetBSD Arm platform guru Jared McNeill has been working on something, that Pi 4 UEFI users are going to find pretty cool. Dongle-less PXE and iSCSI is coming to a Pi 4 near you, because we’re getting native support for GENET networking soon! 😍🔥
This is being implemented as a Simple Network Protocol driver, so it will be usable by any UEFI driver or application.
This release mostly improves on the logic added to v1.4 release for switching between 3GB/4GB modes on the 4GB Pi 4.
The fix for external .dtb is worth diving into. Many of our readers will know, that Raspberries traditionally boot operating systems with Device Tree, instead of ACPI. A dated overview can be found on the official Pi site. Long story short, if you want to boot an 64-bit Linux, NetBSD or FreeBSD today on the Pi with full I/O support, you still need the Device Tree that the VPU firmware prepares based on your config.txt settings (dtparams, overlays, etc).
The Pi 4 support for Device Tree is exactly like the Pi 3 support. At the time, UEFI relied on the Device Tree being placed in RAM after the UEFI image itself, basically overlaying itself on a section of the UEFI image. Recently, new VideoCore firmware broke this approach (which I really shouldn’t have come up with in the first place!) by switching the load ordering – now the Device Tree was loaded before the UEFI image, and since the two images overlapped, the Device Tree blob was getting overwritten. You can read more about it here and here. Anyway, it’s fixed now. The same fix needs to be made to the Pi 3 build. That’s still TBD.
Be mindful that the fix involved changing the load address for the Device Tree in a way that wouldn’t overlap the UEFI image. The new values are:
While looking at the above regression, we were also able to regain 2MiB of memory, as the Trusted Firmware footprint for Pi 4 is much smaller than on the Pi 3.
Based on feedback in the Discord channel (thanks Samer!) I reworked the status page to scale better across future releases and provide more information in an easier-to-consume fashion.
Not only does the new version aggregate all of the release notes, but provides an easy way for locating firmware feature, development status, OS support and standards compliance reports for every new release. All of the OS and firmware status reports will be per release, meaning you will be able to reference old reports if needed.
I’ve added a new link to menu – a status page, providing a fairly-detailed view of things working or broken in the current release. It probably needs to be split into more pages to separate UEFI implementation from operating system-visible aspects like SMBIOS and ACPI, but it’s a place to start.
It may not look like much, but it provides a radically improved networking experience, courtesy of a heads up by Jared and his recent work on the NetBSD GENET driver.
Of course what use is improved GENET via ACPI, when there is barely an OS support? Well, courtesy of the amazing work done by Pete and Jeremy Linton, the Linux ACPI patch for GENET has been merged into net-next.
NetBSD’s amazing Jared McNeill, who appears to crank out Arm platform support code for NetBSD at an inhuman rate, has coded up a driver for the on-board gigabit NIC (aka GENET).
While a great milestone for NetBSD, this is also the world’s first BSD-licensed implementation of a GENET driver. For our UEFI development effort, this finally means being able to implement a proper UEFI driver for the on-board NIC for PXE booting, iSCSI…you name it.
The NetBSD driver already supports the ACPI bindings for GENET, which first appeared in our 1.1 release, and its development is providing great feedback on further evolving the ACPI support. See, the MAC address is not stored in the NIC itself, but comes from the outside (via mailbox interface, I’m guessing via OTP). Of course, you can hypothetically read it from the NIC itself, if it’s been initialized. But apparently that only works if the NIC has been taken out of reset and the MAC is programmed. NetBSD today can boot 3 ways on the Pi 4 – TianoCore UEFI, U-Boot and “straight up” via config.txt. For booting via UEFI, the NIC is taken out of reset and the MAC is programmed. For others, the MAC is not programmed or the NIC is not taken out of reset, making it unsafe to try and read the MAC address, so there needs to be a more reliable mechanism. This might mean a local-mac-address_DSD property is in order for best compatibility. Having to fall back to the VPU mailbox interface in ACPI mode is a no-go: that would amount to Pi-specific platform knowledge and definitely be not SBBR. Another angle to consider is operating systems performing a fast reboot (aka kexec on Linux) – it would be totally unexpected to see a MAC address change to leak across kexec, so that’s another reason for persisting via an ACPI property.
Stepping back, I want to extend a huge thanks to Jared for both his feedback and for his work on supporting our firmware. NetBSD today is the most advanced OS to boot on the Pi 4B SBBR-way: networking, xHCI, 4GB boards, SD card, etc. Once we get the new SDHCI controller (MMC2) described in ACPI and working this should also bring in Wi-Fi. Jared reports that the existing Arasan driver could be sufficient to support MMC2 – that is to say, the old Arasan SDHCI controller’s set of quirks appears to be a direct superset – at least on NetBSD. 🤣
NetBSD also is the only OS today to fully support ACPI _DMA descriptors for describing DMA translations/constraints. This is very important for supporting Pi and Pi-like platforms via straight-up ACPI and without platform DMA quirks. If you like what you’re seeing with NetBSD and Arm support, consider supporting the NetBSD Foundation.
Courtesy of Pete Batard, a new release is out. Again, this is very early in development, so the usual caveats apply – not all OSes will behave as expected and there’s not much yet in terms of step-by-step instructions.