targets: sleep in the bootstrap thread instead of spinning

target/ast10x0/tests/interrupts/user/target.rs

@@ -4,6 +4,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use console_backend::console_backend_write_all;
 use entry as _;
 use target_common::{declare_target, TargetInterface};
@@ -15,8 +16,12 @@ impl TargetInterface for Target {
 
     fn main() -> ! {
         codegen::start();
-        #[expect(clippy::empty_loop)]
-        loop {}
+        // The bootstrap thread has nothing left to do. Sleep rather than spin: a
+        // spinning thread at the same priority as the app threads takes a time
+        // slice at every scheduler tick and delays every wake-up behind it.
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/ipc/user/target.rs

@@ -4,6 +4,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use console_backend::console_backend_write_all;
 use entry as _;
 use target_common::{declare_target, TargetInterface};
@@ -15,8 +16,12 @@ impl TargetInterface for Target {
 
     fn main() -> ! {
         codegen::start();
-        #[expect(clippy::empty_loop)]
-        loop {}
+        // The bootstrap thread has nothing left to do. Sleep rather than spin: a
+        // spinning thread at the same priority as the app threads takes a time
+        // slice at every scheduler tick and delays every wake-up behind it.
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/mctp/ipc_client/target.rs

@@ -10,6 +10,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use console_backend::console_backend_write_all;
 use entry as _;
 use target_common::{declare_target, TargetInterface};
@@ -21,8 +22,12 @@ impl TargetInterface for Target {
 
     fn main() -> ! {
         codegen::start();
-        #[expect(clippy::empty_loop)]
-        loop {}
+        // The bootstrap thread has nothing left to do. Sleep rather than spin: a
+        // spinning thread at the same priority as the app threads takes a time
+        // slice at every scheduler tick and delays every wake-up behind it.
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/mctp/server/target.rs

@@ -4,6 +4,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use ast10x0_board::{Ast10x0Board, Ast10x0BoardDescriptor, I2cBusCfg};
 use ast10x0_peripherals::i2c::{ClockConfig, I2cConfig, I2cSpeed, I2cXferMode};
 use ast10x0_peripherals::scu::pinctrl;
@@ -46,7 +47,9 @@ impl TargetInterface for Target {
         }
 
         codegen::start();
-        loop {}
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/orchestrator/runtime/target.rs

@@ -4,6 +4,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use console_backend::console_backend_write_all;
 use entry as _;
 use target_common::{declare_target, TargetInterface};
@@ -15,8 +16,12 @@ impl TargetInterface for Target {
 
     fn main() -> ! {
         codegen::start();
-        #[expect(clippy::empty_loop)]
-        loop {}
+        // The bootstrap thread has nothing left to do. Sleep rather than spin: a
+        // spinning thread at the same priority as the app threads takes a time
+        // slice at every scheduler tick and delays every wake-up behind it.
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/orchestrator/timer/target.rs

@@ -4,6 +4,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use console_backend::console_backend_write_all;
 use entry as _;
 use target_common::{declare_target, TargetInterface};
@@ -15,8 +16,12 @@ impl TargetInterface for Target {
 
     fn main() -> ! {
         codegen::start();
-        #[expect(clippy::empty_loop)]
-        loop {}
+        // The bootstrap thread has nothing left to do. Sleep rather than spin: a
+        // spinning thread at the same priority as the app threads takes a time
+        // slice at every scheduler tick and delays every wake-up behind it.
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/peripherals/gpio/gpio_irq/target.rs

@@ -6,6 +6,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use ast10x0_peripherals::scu::{pinctrl, ScuRegisters};
 use console_backend::console_backend_write_all;
 use entry as _;
@@ -24,8 +25,9 @@ impl TargetInterface for Target {
         }
 
         codegen::start();
-        #[expect(clippy::empty_loop)]
-        loop {}
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/peripherals/i2c/i2c_slave_rx_ipc/target.rs

@@ -4,6 +4,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use ast10x0_peripherals::i2c;
 use ast10x0_peripherals::scu::pinctrl;
 use console_backend::console_backend_write_all;
@@ -37,8 +38,9 @@ impl TargetInterface for Target {
         }
 
         codegen::start();
-        #[expect(clippy::empty_loop)]
-        loop {}
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/peripherals/sgpiom/sgpiom_irq/target.rs

@@ -15,6 +15,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use ast10x0_peripherals::scu::{pinctrl, ScuRegisters};
 use console_backend::console_backend_write_all;
 use entry as _;
@@ -33,8 +34,9 @@ impl TargetInterface for Target {
         }
 
         codegen::start();
-        #[expect(clippy::empty_loop)]
-        loop {}
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/spdm/auth/target.rs

@@ -4,6 +4,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use ast10x0_board::{Ast10x0Board, Ast10x0BoardDescriptor, I2cBusCfg};
 use ast10x0_peripherals::i2c::{ClockConfig, I2cConfig, I2cSpeed, I2cXferMode};
 use ast10x0_peripherals::scu::pinctrl;
@@ -46,7 +47,9 @@ impl TargetInterface for Target {
         }
 
         codegen::start();
-        loop {}
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/spdm/responder/target.rs

@@ -6,6 +6,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use console_backend::console_backend_write_all;
 use entry as _;
 use target_common::{declare_target, TargetInterface};
@@ -17,8 +18,12 @@ impl TargetInterface for Target {
 
     fn main() -> ! {
         codegen::start();
-        #[expect(clippy::empty_loop)]
-        loop {}
+        // The bootstrap thread has nothing left to do. Sleep rather than spin: a
+        // spinning thread at the same priority as the app threads takes a time
+        // slice at every scheduler tick and delays every wake-up behind it.
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/spdm/vca/target.rs

@@ -4,6 +4,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use ast10x0_board::{Ast10x0Board, Ast10x0BoardDescriptor, I2cBusCfg};
 use ast10x0_peripherals::i2c::{ClockConfig, I2cConfig, I2cSpeed, I2cXferMode};
 use ast10x0_peripherals::scu::pinctrl;
@@ -46,7 +47,9 @@ impl TargetInterface for Target {
         }
 
         codegen::start();
-        loop {}
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/stress/ipc/user/target.rs

@@ -4,6 +4,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use console_backend::console_backend_write_all;
 use entry as _;
 use target_common::{declare_target, TargetInterface};
@@ -15,8 +16,12 @@ impl TargetInterface for Target {
 
     fn main() -> ! {
         codegen::start();
-        #[expect(clippy::empty_loop)]
-        loop {}
+        // The bootstrap thread has nothing left to do. Sleep rather than spin: a
+        // spinning thread at the same priority as the app threads takes a time
+        // slice at every scheduler tick and delays every wake-up behind it.
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/stress/process_termination/user/target.rs

@@ -4,6 +4,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use console_backend::console_backend_write_all;
 use entry as _;
 use target_common::{declare_target, TargetInterface};
@@ -15,8 +16,12 @@ impl TargetInterface for Target {
 
     fn main() -> ! {
         codegen::start();
-        #[expect(clippy::empty_loop)]
-        loop {}
+        // The bootstrap thread has nothing left to do. Sleep rather than spin: a
+        // spinning thread at the same priority as the app threads takes a time
+        // slice at every scheduler tick and delays every wake-up behind it.
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/usart/target.rs

@@ -9,6 +9,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use cortex_m_semihosting::debug::{exit, EXIT_FAILURE, EXIT_SUCCESS};
 use target_common::{declare_target, TargetInterface};
 use {console_backend as _, entry as _};
@@ -20,8 +21,12 @@ impl TargetInterface for Target {
 
     fn main() -> ! {
         codegen::start();
-        #[expect(clippy::empty_loop)]
-        loop {}
+        // The bootstrap thread has nothing left to do. Sleep rather than spin: a
+        // spinning thread at the same priority as the app threads takes a time
+        // slice at every scheduler tick and delays every wake-up behind it.
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/ast10x0/tests/util_ipc/async_transaction/target.rs

@@ -10,6 +10,7 @@
 #![no_std]
 #![no_main]
 
+use arch_arm_cortex_m::Arch;
 use console_backend::console_backend_write_all;
 use entry as _;
 use target_common::{declare_target, TargetInterface};
@@ -21,8 +22,12 @@ impl TargetInterface for Target {
 
     fn main() -> ! {
         codegen::start();
-        #[expect(clippy::empty_loop)]
-        loop {}
+        // The bootstrap thread has nothing left to do. Sleep rather than spin: a
+        // spinning thread at the same priority as the app threads takes a time
+        // slice at every scheduler tick and delays every wake-up behind it.
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/earlgrey/syscall_latency/target.rs

@@ -3,6 +3,7 @@
 #![no_std]
 #![no_main]
 
+use arch_riscv::Arch;
 use target_common::{declare_target, TargetInterface};
 use {console_backend as _, entry as _, kernel as _};
 
@@ -13,7 +14,12 @@ impl TargetInterface for Target {
 
     fn main() -> ! {
         codegen::start();
-        loop {}
+        // The bootstrap thread has nothing left to do. Sleep rather than spin: a
+        // spinning thread at the same priority as the app threads takes a time
+        // slice at every scheduler tick and delays every wake-up behind it.
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 
     fn shutdown(code: u32) -> ! {

target/earlgrey/tests/drivers/gpio/target.rs

@@ -3,6 +3,7 @@
 
 #![no_std]
 #![no_main]
+use arch_riscv::Arch;
 use target_common::{declare_target, TargetInterface};
 use {console_backend as _, entry as _};
 
@@ -13,7 +14,12 @@ impl TargetInterface for Target {
 
     fn main() -> ! {
         codegen::start();
-        loop {}
+        // The bootstrap thread has nothing left to do. Sleep rather than spin: a
+        // spinning thread at the same priority as the app threads takes a time
+        // slice at every scheduler tick and delays every wake-up behind it.
+        loop {
+            let _ = kernel::sleep_until(Arch, kernel::Instant::MAX);
+        }
     }
 }