Enable co-processors for second core

rp235x-hal/src/arch.rs

@@ -31,6 +31,22 @@ mod inner {
         }
         t
     }
+
+    /// Enable co-processors.
+    ///
+    /// For core0, this is done by the `#[entry]` macro. Fore core1, this function is called
+    /// from `multicore::Core::spawn`.
+    ///
+    /// # Safety
+    ///
+    /// Must only be called immediately after starting up a core.
+    pub unsafe fn enable_coprocessors() {
+        unsafe {
+            (*cortex_m::peripheral::SCB::PTR)
+                .cpacr
+                .modify(|value| value | 3 | 3 << 8 | (3 << 20) | (3 << 22))
+        }
+    }
 }
 
 #[cfg(all(target_arch = "riscv32", target_os = "none"))]

rp235x-hal/src/multicore.rs

@@ -68,6 +68,10 @@ fn install_stack_guard(_stack_limit: *mut usize) {
 #[inline(always)]
 fn core1_setup(stack_limit: *mut usize) {
     install_stack_guard(stack_limit);
+    #[cfg(all(target_arch = "arm", target_os = "none"))]
+    unsafe {
+        crate::arch::enable_coprocessors()
+    };
     // TODO: irq priorities
 }