From da37f6aa8ab1f9a8502d6c550f8915e1f237fff1 Mon Sep 17 00:00:00 2001
From: Stephen Waits <steve@waits.net>
Date: Thu, 26 Mar 2026 18:00:13 -0600
Subject: [PATCH] fix: resolve ESP32-S3 linker errors, all boards produce
 firmware

Three fixes:
- Add .cargo/config.toml with -Tlinkall.x for xtensa target (resolves
  ROM functions, interrupt handlers, memory layout)
- Add integrated-timers feature to embassy-executor for ESP32 boards
  (resolves _embassy_time_schedule_wake)
- Add `use esp_println as _` to pull in defmt global_logger (was being
  stripped as dead code because nothing referenced the crate)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 .cargo/config.toml | 6 ++++++
 Cargo.lock         | 2 ++
 Cargo.toml         | 2 ++
 src/main.rs        | 1 +
 4 files changed, 11 insertions(+)
 create mode 100644 .cargo/config.toml

diff --git a/.cargo/config.toml b/.cargo/config.toml
new file mode 100644
index 00000000..850366b5
--- /dev/null
+++ b/.cargo/config.toml
@@ -0,0 +1,6 @@
+[target.xtensa-esp32s3-none-elf]
+rustflags = [
+    "-C", "link-arg=-nostartfiles",
+    "-C", "link-arg=-Tlinkall.x",
+    "-C", "link-arg=-Tdefmt.x",
+]
diff --git a/Cargo.lock b/Cargo.lock
index ec93f9d9..f59c611c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -359,6 +359,8 @@ dependencies = [
  "critical-section",
  "document-features",
  "embassy-executor-macros",
+ "embassy-time-driver",
+ "embassy-time-queue-driver",
 ]
 
 [[package]]
diff --git a/Cargo.toml b/Cargo.toml
index 1d5080ae..5f64f92f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -47,12 +47,14 @@ heltec_v3 = [
     "dep:esp-hal",
     "dep:esp-hal-embassy",
     "dep:esp-println",
+    "embassy-executor/integrated-timers",
 ]
 heltec_v4 = [
     "dep:esp-backtrace",
     "dep:esp-hal",
     "dep:esp-hal-embassy",
     "dep:esp-println",
+    "embassy-executor/integrated-timers",
 ]
 rak_wisblock_4631 = [
     "dep:cortex-m-rt",
diff --git a/src/main.rs b/src/main.rs
index d922bd0f..629dbf65 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -17,6 +17,7 @@ cfg_if::cfg_if! {
         use panic_probe as _;
     } else if #[cfg(any(feature = "heltec_v3", feature = "heltec_v4"))] {
         use esp_backtrace as _;
+        use esp_println as _; // provides defmt global_logger
     }
 }