Update linker script to put .data into FLASH

Previously .data's LMA was specified by a computated address instead of
placing it into FLASH explicitly, which means FLASH overflows caused by
.data would not be detected by the linker.

Fixes #86.

1 files changed, 42 insertions, 0 deletions

diff --git a/cortex-m-rt/examples/data_overflow.rs b/cortex-m-rt/examples/data_overflow.rs
new file mode 100644
index 0000000..f01f91c
--- /dev/null
+++ b/cortex-m-rt/examples/data_overflow.rs
@@ -0,0 +1,42 @@
+//! This is not an example; this is a linker overflow detection test
+//! which should fail to link due to .data overflowing FLASH.
+
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+#[macro_use(entry, exception)]
+extern crate cortex_m_rt as rt;
+extern crate panic_abort;
+
+use core::ptr;
+
+use rt::ExceptionFrame;
+
+entry!(main);
+
+// This large static array uses most of .rodata
+static RODATA: [u8; 48*1024] = [1u8; 48*1024];
+
+// This large mutable array causes .data to use the rest of FLASH
+// without also overflowing RAM.
+static mut DATA: [u8; 16*1024] = [1u8; 16*1024];
+
+fn main() -> ! {
+    unsafe {
+        let _bigdata = ptr::read_volatile(&RODATA as *const u8);
+        let _bigdata = ptr::read_volatile(&DATA as *const u8);
+    }
+
+    loop {}
+}
+
+exception!(HardFault, hard_fault);
+
+fn hard_fault(_ef: &ExceptionFrame) -> ! {
+    loop {}
+}
+
+exception!(*, default_handler);
+
+fn default_handler(_irqn: i16) {}