Set _hart_stack_size to size of stack for single-hart

Single core devices have no reason to split the stack in multiples, so
just set it to use the entire available stack.

Author: janderholm

riscv-rt/build.rs

@@ -11,6 +11,15 @@ fn add_linker_script(arch_width: u32) -> io::Result<()> {
     let mut content = fs::read_to_string("link.x.in")?;
     content = content.replace("${ARCH_WIDTH}", &arch_width.to_string());
 
+    // Single core devices can use the entire stack, no need to limit it.
+    let hart_stack_size = if env::var_os("CARGO_FEATURE_SINGLE_HART").is_some() {
+        "SIZEOF(.stack)"
+    } else {
+        "2K"
+    };
+
+    content = content.replace("${HART_STACK_SIZE}", hart_stack_size);
+
     // Get target-dependent linker configuration and replace ${INCLUDE_LINKER_FILES} with it
     let mut include_content = String::new();
 

riscv-rt/link.x.in

@@ -72,7 +72,7 @@ ${INCLUDE_LINKER_FILES}
 PROVIDE(_stext = ORIGIN(REGION_TEXT));
 PROVIDE(_stack_start = ORIGIN(REGION_STACK) + LENGTH(REGION_STACK));
 PROVIDE(_max_hart_id = 0);
-PROVIDE(_hart_stack_size = 2K);
+PROVIDE(_hart_stack_size = ${HART_STACK_SIZE});
 PROVIDE(_heap_size = 0);
 
 SECTIONS