Espressif's ESP32-S31 Boots Linux for $4.51 a Chip
Hardware / explainer
Espressif's ESP32-S31 Boots Linux for $4.51 a Chip
A developer-preview BSP runs kernel 6.18 on RISC-V cores Espressif never built for a full OS, at under a third of the Raspberry Pi Zero 2 W's price and a fraction of its memory.
Espressif priced its ESP32-S31NRV16 chip at roughly $4.51 and started shipping it in volume on July 28, 2026, and on Aug. 22 the company released a developer-preview Linux board support package that boots a real Linux 6.18 kernel on it, according to CNX Software. That is a genuinely new capability for an Espressif chip, and it is also a preview Espressif itself describes as carrying "irregular updates," possible "breaking changes" and bug fixes on a "best-effort basis," not something to put in a shipping product.
What actually changed in the silicon
Previous ESP32 chips could run Linux only through elaborate workarounds, because their cores lacked a real memory management unit. The ESP32-S31, announced April 8, 2026, pairs two 320 MHz RISC-V cores with an MMU that supports Sv32 paging and separate Machine, Supervisor and User privilege modes, the same hardware split a full operating system kernel expects. Jeroen Domburg, an Espressif engineer who posts online as Sprite_tm, said of the chip's naming that "we actually never intended the CPU architecture to be part of the name," a small detail that nonetheless signals how far the S-series label has drifted from the Xtensa-based chips it originally described.
The S31 also carries a gigabit Ethernet MAC, a full jump up from the 100 Mbps interface on the earlier ESP32-P4, plus WiFi 6, Bluetooth 5.4, a USB 2.0 host controller and two SD card slots. Espressif's own CoreMark benchmark, run at 320 MHz and not independently verified, puts the chip at 2195.20 CoreMark, or 6.86 CoreMark per megahertz.
What the preview can and can't do yet
The Aug. 22 BSP, built on Buildroot 2025.02, boots a minimal image to a UART console at 115200 baud on the chip's 16MB of PSRAM, producing a flash image of about 13.7MB, CNX Software reported. WiFi and Bluetooth, the two capabilities the chip's marketing leads with, are not implemented in the official preview at all. A community port pushes further, running kernel versions 6.12 and 7.1 with a stable root filesystem and working reboot, but even that port leaves the LCD panel, microSD, USB host and WLAN modem disabled. Espressif's own datasheet is still stamped version 0.5 and marked "PRELIMINARY."
The price that makes this interesting
The ESP32-S31NRV16, with 16MB of octal SPI PSRAM, lists at roughly $4.51 in Espressif's mass-production pricing; a 32MB variant, the S31NRV32, and a fully shielded module, the ESP32-S31-WROOM-3 at about $5.84, round out the lineup, LinuxGizmos reported. The Raspberry Pi Zero 2 W, the board every writeup of the S31 reaches for as a comparison, launched at $15, more than three times the bare S31 chip's price and more than double the WROOM-3 module.
| Spec | ESP32-S31NRV16 | Raspberry Pi Zero 2 W |
|---|---|---|
| Price | ~$4.51 | $15 |
| RAM | 512KB SRAM + 16MB PSRAM | 512MB LPDDR2 SDRAM |
| CPU | Dual-core RISC-V, 320 MHz | Quad-core Arm Cortex-A53, 1 GHz |
| Wired networking | Gigabit Ethernet MAC | None |
- ESP32-S31NRV16 (bare chip)4.51 $
- ESP32-S31-WROOM-3 (module)5.84 $
- Raspberry Pi Zero 2 W15 $
Source: LinuxGizmos, July 28, 2026 mass-production pricing; Raspberry Pi, accessed Sept. 24, 2026
The number that still separates it from a real Pi
Price is the number every headline about this chip reaches for, and it is also the number that flatters the comparison most. The S31 carries 512KB of on-chip SRAM against the Zero 2 W's 512MB of SDRAM, an eighth as much memory even before accounting for the fact that a minimal Linux build on the S31 has to execute the kernel from flash rather than spending its limited PSRAM on it. A chip that costs a third as much and runs an eighth of the memory is not a Raspberry Pi replacement; it is a microcontroller that can now, for the first time, boot the same kernel family a Raspberry Pi runs, which is a narrower and more specific claim than the headlines chasing this story have generally made.
What would change the read
The gap that matters is not price, it's timeline: whether Espressif's own WiFi and Bluetooth drivers land in the official BSP, and whether the community's kernel 7.1 port stabilizes enough to re-enable the peripherals that port still disables. Until one of those happens, the S31 is a chip that can technically run Linux rather than one anyone should build a product on. The same staged-rollout pattern is playing out on very different silicon at Qualcomm, whose own Snapdragon X2 Linux preview shipped a working boot process in September while leaving its middle enablement stage undated, and it is the same bet Arduino is making with its Qualcomm-based VENTUNO Q board: that Linux support on hardware not originally built for it arrives in stages, and the first stage to ship is never the one that matters most.
Sources
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