diff options
| -rw-r--r-- | cortex-m-rt/link.x.in | 2 | ||||
| -rw-r--r-- | cortex-m-rt/src/lib.rs | 17 |
2 files changed, 10 insertions, 9 deletions
diff --git a/cortex-m-rt/link.x.in b/cortex-m-rt/link.x.in index c2511f7..23f406d 100644 --- a/cortex-m-rt/link.x.in +++ b/cortex-m-rt/link.x.in @@ -54,7 +54,7 @@ EXTERN(__INTERRUPTS); /* `static` variable similar to `__EXCEPTIONS` */ /* # Pre-initialization function */ /* If the user overrides this using the `pre_init!` macro or by creating a `__pre_init` function, then the function this points to will be called before the RAM is initialized. */ -PROVIDE(__pre_init = 1); +PROVIDE(__pre_init = DefaultPreInit); /* # Sections */ SECTIONS diff --git a/cortex-m-rt/src/lib.rs b/cortex-m-rt/src/lib.rs index 04d5b9e..cecb5f8 100644 --- a/cortex-m-rt/src/lib.rs +++ b/cortex-m-rt/src/lib.rs @@ -237,11 +237,10 @@ //! have a size of 32 vectors (on ARMv6-M) or 240 vectors (on ARMv7-M). This array is located after //! `__EXCEPTIONS` in the `.vector_table` section. //! -//! - `__pre_init`. This is a function to be run before RAM is initialized. It defaults pointing at -//! `1` and if not changed to point to another address, usually by calling the `pre_init!` macro, -//! the `_pre_init` function is skipped. The function cannot default to `0` as the compiler -//! optimizes out the check for `0` under the assumption that a function pointer cannot point to -//! `0`. +//! - `__pre_init`. This is a function to be run before RAM is initialized. It defaults to an empty +//! function. The function called can be changed by calling the `pre_init!` macro. The empty +//! function is not optimized out by default, but if an empty function is passed to `pre_init!` the +//! function call will be optimized out. //! //! If you override any exception handler you'll find it as an unmangled symbol, e.g. `SysTick` or //! `SVCall`, in the output of `objdump`, @@ -493,9 +492,7 @@ pub unsafe extern "C" fn Reset() -> ! { } let pre_init: unsafe extern "C" fn() = __pre_init; - if pre_init as usize != 1 { - pre_init(); - } + pre_init(); // Initialize RAM r0::zero_bss(&mut __sbss, &mut __ebss); @@ -552,6 +549,10 @@ pub unsafe extern "C" fn DefaultUserHardFault() { } } +#[doc(hidden)] +#[no_mangle] +pub unsafe extern "C" fn DefaultPreInit() {} + /// Macro to define the entry point of the program /// /// **NOTE** This macro must be invoked once and must be invoked from an accessible module, ideally |