ESP32: "esptool load-ram" no longer works in dev (works in 0.41)

[jeremyvisser]

When using esptool load-ram to flash a program onto an ESP32, it works on TinyGo 0.41, but no longer works on the latest dev branch (0.42.0-dev-854f91ec).

Test case:

package main

func main() {
	for {
		println("hello, world!")
	}
}

TinyGo 0.41:

% /opt/tinygo0.41/bin/tinygo build -o cmd/helloworld/helloworld.bin -target esp32-generic ./cmd/helloworld/. \
  && esptool --port $PORT load-ram cmd/helloworld/helloworld.bin \
  && /opt/tinygo0.41/bin/tinygo monitor -port $PORT
esptool v5.2.0
Connected to ESP32 on /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0:
Chip type:          ESP32-D0WD-V3 (revision v3.1)
Features:           Wi-Fi, BT, Dual Core + LP Core, 240MHz, Vref calibration in eFuse, Coding Scheme None
Crystal frequency:  40MHz
MAC:                1c:c3:ab:bc:33:dc

Stub flasher running.

Loaded 2 segments from 'cmd/helloworld/helloworld.bin' to RAM, executing at 0x4008000c.

Exiting immediately.
Connected to /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0. Press Ctrl-C to exit.
hello, world!
hello, world!
hello, world!
hello, world!
hello, world!
hello, world!
^C

TinyGo 0.42.0-dev-854f91ec:

% /opt/tinygo/bin/tinygo build -o cmd/helloworld/helloworld.bin -target esp32-generic ./cmd/helloworld/. \
  && esptool --port /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0 load-ram cmd/helloworld/helloworld.bin \
  && /opt/tinygo/bin/tinygo monitor -port /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0
esptool v5.2.0
Connected to ESP32 on /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0:
Chip type:          ESP32-D0WD-V3 (revision v3.1)
Features:           Wi-Fi, BT, Dual Core + LP Core, 240MHz, Vref calibration in eFuse, Coding Scheme None
Crystal frequency:  40MHz
MAC:                1c:c3:ab:bc:33:dc

Stub flasher running.

Loaded 2 segments from 'cmd/helloworld/helloworld.bin' to RAM, executing at 0x40080058.

Exiting immediately.
Connected to /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0. Press Ctrl-C to exit.

EXC 00000000 400d0f8c 00000000 80007c18

Actually flashing the program to the ESP32 (esptool write-flash or tinygo flash) continues to work fine, however esptool load-ram is significantly faster, and has less impact on the flash's lifespan.

My environment:

• tinygo version 0.42.0-dev-854f91ec linux/amd64 (using go version go1.26.5-X:nodwarf5 and LLVM version 22.1.4)
• ESP32:
  • Tested on a CYD-2432S028R (ESP32-D0WD-V3)
  • Also tested on a LOLIN32 (ESP32-D0WDQ6), which has the same behaviour

The most likely related change is #5510.