esp-wifi was bare metal but esp-radio requires RTOS?

[orsinium]

I used to be able to run a esp-wifi project on bare metal ESP32-S3. Now I see that esp-wifi is deprecated in favor of esp-radio and when I switch to esp-radio I get linker errors:

          /home/gram/.rustup/toolchains/esp/xtensa-esp-elf/esp-14.2.0_20240906/xtensa-esp-elf/bin/../lib/gcc/xtensa-esp-elf/14.2.0/../../../../xtensa-esp-elf/bin/ld: /home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/deps/firefly_io-060fc26db922a5d1.firefly_io.3a9594f9cc748595-cgu.0.rcgu.o:(.literal._ZN9esp_radio6compat5mutex12mutex_create17h8d23aa1a4e836e60E+0x0): undefined reference to `esp_rtos_semaphore_create'
          /home/gram/.rustup/toolchains/esp/xtensa-esp-elf/esp-14.2.0_20240906/xtensa-esp-elf/bin/../lib/gcc/xtensa-esp-elf/14.2.0/../../../../xtensa-esp-elf/bin/ld: /home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/deps/firefly_io-060fc26db922a5d1.firefly_io.3a9594f9cc748595-cgu.0.rcgu.o:(.literal.__esp_radio_sleep+0x0): undefined reference to `esp_rtos_usleep'
...

It seems like an OS is required now to use the crate:

You will also need a dynamic memory allocator, and a preemptive task scheduler in your application. For the dynamic allocator, we recommend using esp-alloc. For the task scheduler, the simplest option that is supported by us is esp-rtos, but you may use Ariel OS or other operating systems as well.

But what if I don't have an OS? Is the only option to stick to the never-to-be-updated esp-wifi?

[bugadani]

The esp-radio binaries have been written with FreeRTOS in mind, they require certain OS features, or emulation of those. esp-wifi has been lying to you, and provided a very bad task scheduler that intrusively switched task context at a fixed rate. This integrated scheduler also prevented any sort of progress toward better low power mode support. esp-rtos is a massive improvement over that, and it costs you only a bit of memory, a software interrupt, and not much more.

If you don't want to run an RTOS, you can still use FoA which is an open-source reimplementation, although for embassy support you will need to provide your own executor and time driver.

[bugadani]

You just add esp-rtos to your dependencies, and activate the esp-radio, and optionally the embassy features on it, and that should be it.

[yanshay]

So with esp-rtos the rest of my code that uses embassy would work as usual?

[orsinium]

i have added esp-rtos to the dependency list but i'm still getting the linker errors

esp-rtos = { version = "0.2.0", features = [
    "esp32s3",
    "esp-radio",
    "esp-alloc",
] }
esp-radio = { version = "0.17.0", features = [
    "esp32s3",
    "esp-now",
    "unstable",
] }

error: linking with `xtensa-esp32s3-elf-gcc` failed: exit status: 1
  |
  = note:  "xtensa-esp32s3-elf-gcc" "<1 object files omitted>" "-Wl,--as-needed" "-Wl,-Bstatic" "/home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/deps/libcompiler_builtins-14d43b7bdd65a7fa.rlib" "-Wl,-Bdynamic" "-lesp-radio" "-lesp-phy" "-lbtbb" "-lbtdm_app" "-lcoexist" "-lcore" "-lespnow" "-lmesh" "-lnet80211" "-lphy" "-lpp" "-lsmartconfig" "-lwapi" "-lwpa_supplicant" "-lprintf" "-lregulatory" "-lesp_rom_sys" "-L" "/tmp/rustcjRrhcM/raw-dylibs" "-Wl,--eh-frame-hdr" "-Wl,-z,noexecstack" "-L" "/home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/build/esp-hal-b067d3f22ad926f5/out" "-L" "/home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/build/esp-rom-sys-ac0d9a9649af2621/out" "-L" "/home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/build/esp32s3-dd8516e5dc2c4294/out" "-L" "/home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/build/xtensa-lx-rt-a01ef56bf6b8b444/out" "-L" "/home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/build/esp-radio-6dbbcd852e779708/out" "-L" "/home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/build/esp-phy-0469356f4f162168/out" "-L" "/home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/build/esp-wifi-sys-1a54b4af4d5837ee/out" "-o" "/home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/deps/firefly_io-5862f5698d38e9ff" "-Wl,--gc-sections" "-no-pie" "-Wl,--strip-all" "-nodefaultlibs" "-nostartfiles" "-Tlinkall.x"
  = note: some arguments are omitted. use `--verbose` to show all linker arguments
  = note: /home/gram/.rustup/toolchains/esp/xtensa-esp-elf/esp-14.2.0_20240906/xtensa-esp-elf/bin/../lib/gcc/xtensa-esp-elf/14.2.0/../../../../xtensa-esp-elf/bin/ld: warning: /home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/deps/firefly_io-5862f5698d38e9ff has a LOAD segment with RWX permissions
          /home/gram/.rustup/toolchains/esp/xtensa-esp-elf/esp-14.2.0_20240906/xtensa-esp-elf/bin/../lib/gcc/xtensa-esp-elf/14.2.0/../../../../xtensa-esp-elf/bin/ld: /home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/deps/firefly_io-5862f5698d38e9ff.firefly_io.dc8db3e86a136287-cgu.0.rcgu.o: in function `sym_sidata':
          firefly_io.dc8db3e86a136287-cgu.0:(.rwtext.literal+0x1d4): undefined reference to `esp_rtos_semaphore_take'
          /home/gram/.rustup/toolchains/esp/xtensa-esp-elf/esp-14.2.0_20240906/xtensa-esp-elf/bin/../lib/gcc/xtensa-esp-elf/14.2.0/../../../../xtensa-esp-elf/bin/ld: firefly_io.dc8db3e86a136287-cgu.0:(.rwtext.literal+0x1e4): undefined reference to `esp_rtos_semaphore_give'
          /home/gram/.rustup/toolchains/esp/xtensa-esp-elf/esp-14.2.0_20240906/xtensa-esp-elf/bin/../lib/gcc/xtensa-esp-elf/14.2.0/../../../../xtensa-esp-elf/bin/ld: /home/gram/ff/firefly-io/target/xtensa-esp32s3-none-elf/release/deps/firefly_io-5862f5698d38e9ff.firefly_io.dc8db3e86a136287-cgu.0.rcgu.o:(.literal.main+0x22c): undefined reference to `esp_rtos_initialized'
          ```

[bugadani]

Sounds like you don't mention esp_rtos in code anywhere, so it doesn't actually get compiled. You can take a look at the Setup paragraph in the documentation.

[orsinium]

it works! thank you.