Add a few items:

* converges rtt deps to endure only rtt-target v0.4.0 is used
* builds std to get more debug info
* tweaks some profile items

.cargo/config.toml

@@ -12,3 +12,6 @@ rustflags = [
     # LLVM linker:
     "-C", "link-arg=-Map=build.map",
 ]
+
+[unstable]
+build-std = ["core", "alloc"]

Cargo.toml

@@ -28,9 +28,12 @@ debug = true
 debug-assertions = true # controls both our own assertions plus whether RTT enabled
 overflow-checks = false
 lto = 'fat' # same as true? may do nothing if codegen-units is 1
+# lto = false # same as true? may do nothing if codegen-units is 1
+# lto = 'thin' # same as true? may do nothing if codegen-units is 1
 panic = 'abort'
-incremental = true
-codegen-units = 8
+incremental = false
+# codegen-units = 8
+codegen-units = 1
 
 #-----------------------------------
 [dependencies]
@@ -46,12 +49,16 @@ critical-section = { version = "1.1", default-features = false }
 nrf52840-hal = { version = "0.16.0" }
 
 embedded-alloc = "0.5.0"
-panic-rtt-target = { version = "0.1.2", features = ["cortex-m"] }
-rtt-target = { version = "0.4.0" }
+# panic-rtt-target = { version = "0.1.2", features = ["cortex-m"] }
+# rtt-target = { version = "0.3.1", features = ["cortex-m"] }
+
+panic-rtt-target = { git = "https://github.com/probe-rs/rtt-target", rev = "59b236ce50e44826031adbfc12742e4a0b8d5d6c", features = ["cortex-m"] }
+rtt-target = { git = "https://github.com/probe-rs/rtt-target", rev = "59b236ce50e44826031adbfc12742e4a0b8d5d6c" }
 
 [patch.crates-io]
 # Note: latest known good version is whatever comes after rev = below.
 embassy-executor = { git = "https://github.com/embassy-rs/embassy", rev="ce66276" }
 embassy-nrf = { git = "https://github.com/embassy-rs/embassy", rev="ce66276" }
 embassy-sync = { git = "https://github.com/embassy-rs/embassy", rev="ce66276" }
 embassy-time = { git = "https://github.com/embassy-rs/embassy", rev="ce66276" }
+rtt-target = { git = "https://github.com/probe-rs/rtt-target", rev = "59b236ce50e44826031adbfc12742e4a0b8d5d6c" }

run.sh

@@ -0,0 +1,10 @@
+set -euxo pipefail
+
+cargo build
+cargo objcopy -- -O ihex none-fault.hex
+sleep 1
+probe-rs download --chip nrf52840 --format hex none-fault.hex
+sleep 1
+probe-rs reset --chip nrf52840
+RTT=$(grep _SEGGER_RTT$ build.map | cut -d' ' -f1); echo $RTT >.rttlast
+rtthost --chip nrf52840 --scan-region 0x$RTT

src/main.rs

@@ -48,15 +48,23 @@ fn oom(_layout: core::alloc::Layout) -> ! {
     }
 }
 
+struct Lol {
+    a: UnsafeCell<MaybeUninit<[u8; SIZE]>>,
+}
+
+unsafe impl Sync for Lol {}
+
+use core::{cell::UnsafeCell, sync::atomic::{compiler_fence, Ordering}};
+use ::core::mem::MaybeUninit;
+const SIZE: usize = 1 * 1024;
+static HEAP: Lol = Lol { a: UnsafeCell::new(MaybeUninit::uninit()) };
 
 #[embassy_executor::main]
 async fn main(spawner: Spawner) {
     // Initialize the allocator BEFORE you use it
     {
-        use ::core::mem::MaybeUninit;
-        const SIZE: usize = 1 * 1024;
-        static mut HEAP: [MaybeUninit<u8>; SIZE] = [MaybeUninit::uninit(); SIZE];
-        unsafe { ALLOCATOR.init(HEAP.as_ptr() as usize, SIZE) }
+        assert_eq!(core::mem::size_of_val(&HEAP), SIZE);
+        unsafe { ALLOCATOR.init(HEAP.a.get() as usize, SIZE) }
     }
 
     // initialize embassy
@@ -74,11 +82,16 @@ async fn main(spawner: Spawner) {
     let _ = spawner.spawn(task2());
 
     // sleep_secs(1).await;
-    rprintln!("fail now?");
-
+    // rprintln!("fail now?");
+    compiler_fence(Ordering::SeqCst);
+    let x = alloc::boxed::Box::new([0u8; 256]);
+    // rprintln!("fail now3?");
     let x = format!("{:?}", None::<usize>);
-    // let x = format!("{:?}", Some(23usize));
+    compiler_fence(Ordering::SeqCst);
+    // rprintln!("fail now2?");
+    // // let x = format!("{:?}", Some(23usize));
     rprintln!("format!: {}", x);
+    // rprintln!("{:?}", None::<usize>);
 
     // let x: Option<usize> = None;
     // debug!("test: {:?}", x);
@@ -109,7 +122,9 @@ pub async fn sleep_secs(v: u32) {
 #[cfg(not(feature = "term"))]
 #[embassy_executor::task]
 pub async fn task1() {
+    // return;
     sleep_secs(500).await;
+    compiler_fence(Ordering::SeqCst);
     // core::future::pending::<()>().await; // does not fail with this instead
 
     // Removing these lines shifts stuff around and usually prevents failure:
@@ -119,7 +134,9 @@ pub async fn task1() {
 
 #[embassy_executor::task]
 async fn task2() {
+    // return;
     sleep_secs(500).await;
+    compiler_fence(Ordering::SeqCst);
     // core::future::pending::<()>().await; // does not fail with this instead
 
     // Removing these lines shifts stuff around and usually prevents failure: