Hardwareraspberry-pilinuxdevice-treebcm2711single-board-computers
Raspberry Pi Merged Linux Device Trees for an Unannounced Pi Zero 3 W and Pi 4 Model A, Both Built on the Pi 4's BCM2711 Chip
A pull request merged into Raspberry Pi's Linux kernel on October 25 adds device trees named "Raspberry Pi Zero 3 W" and "Raspberry Pi 4 Model A," two boards the company hasn't announced, both on the BCM2711 that powers the Pi 4.
The pull request came from Marta Momotko on October 23 and went into the rpi-6.18.y branch two days later with no description and no discussion. It adds 795 lines across six files: a device tree for each board in both the 32-bit and 64-bit trees, plus the Makefile entries that build them. A few days later the change was picked up in a firmware kernel bump.
A device tree is the file that tells Linux what’s wired where on a board. These two are unusually specific. The Zero 3 W file opens with compatible = "raspberrypi,model-zero-3-w", "brcm,bcm2711" and model = "Raspberry Pi Zero 3 W". The Pi 4A file says model = "Raspberry Pi 4 Model A".
Here’s what the files show next to the boards they’d sit beside, using Raspberry Pi’s own product pages for the shipping models:
| Pi Zero 3 W (device tree) | Pi 4 Model A (device tree) | Pi Zero 2 W | Pi 4 Model B | |
|---|---|---|---|---|
| Chip | BCM2711 | BCM2711 | RP3A0 | BCM2711, quad-core Cortex-A72 @ 1.8GHz |
| HDMI | one (HDMI1 “permanently” disabled) | one (HDMI1 disabled) | one mini HDMI | two micro-HDMI, up to 4Kp60 |
| Storage bus | eMMC or SD, 8-bit | SD, 4-bit | microSD | microSD |
| Power button | yes, GPIO 46 | yes | no | no |
| Ethernet | none described | none described | none | Gigabit |
| Price | not announced | not announced | $15 | from $35 |
The Zero 3 W file comments that “EMMC2 is used to drive the eMMC/SD card” and sets an 8-bit bus, which points to onboard eMMC as an option. Its GPIO names include Wi-Fi and Bluetooth enable lines, a SPI flash chip, two camera GPIOs, a USB mux select and two PCIe lines, PCIE_DET_WAKE and PCIE_PWR_EN. The Pi 4A file has antenna control lines, ANT_CTRL1 and ANT_CTRL2, which suggests a choice between an onboard and an external antenna.
What the files don’t say matters as much. A device tree lists pins, not RAM size, clock speed, board dimensions, price or launch date, and the pull request carries no description. PCIe lines on a Zero could mean an exposed connector or an internal use; the file names them without saying which. Raspberry Pi merges support ahead of launches so the kernel is ready on day one, so these files show which boards are coming and roughly how they’re wired. Pricing and timing will come from Raspberry Pi.