Proposal: Allow setting the stack size on build time

README.md

@@ -101,6 +101,14 @@ This script does the following steps for you:
 - create a TAB (tock application bundle)
 - if you have a J-Link compatible board connected: flash this TAB to your board (using tockloader)
 
+## Configuration of Memory Sizes
+
+The configuration of different memory parameters can be configured using
+environment variables:
+
+- `APP_HEAP_SIZE` sets the size of the app heap and defaults to 1024.
+- `APP_STACK_SIZE` sets the size of the app stack and default to 2048.
+- `KERNEL_HEAP_SIZE` sets the size of the kernel heap and default to 1024.
 
 ## License
 

boards/layout_hail.ld → boards/layout_hail.ld.handlebars

@@ -10,7 +10,7 @@ MEMORY {
  * Any change to STACK_SIZE should be accompanied by a corresponding change to
  * `elf2tab`'s `--stack` option
  */
-STACK_SIZE = 2048;
+STACK_SIZE = {{stack_size}};
 
 MPU_MIN_ALIGN = 8K;
 

boards/layout_hifive1.ld → boards/layout_hifive1.ld.handlebars

@@ -17,7 +17,7 @@ MEMORY {
  * Any change to STACK_SIZE should be accompanied by a corresponding change to
  * `elf2tab`'s `--stack` option
  */
-STACK_SIZE = 2048;
+STACK_SIZE = {{stack_size}};
 
 MPU_MIN_ALIGN = 1K;
 

boards/layout_nrf52.ld → boards/layout_nrf52.ld.handlebars

@@ -10,7 +10,7 @@ MEMORY {
  * Any change to STACK_SIZE should be accompanied by a corresponding change to
  * `elf2tab`'s `--stack` option
  */
-STACK_SIZE = 2048;
+STACK_SIZE = {{stack_size}};
 
 MPU_MIN_ALIGN = 8K;
 

boards/layout_nrf52840.ld → boards/layout_nrf52840.ld.handlebars

@@ -10,7 +10,7 @@ MEMORY {
  * Any change to STACK_SIZE should be accompanied by a corresponding change to
  * `elf2tab`'s `--stack` option
  */
-STACK_SIZE = 2048;
+STACK_SIZE = {{stack_size}};
 
 MPU_MIN_ALIGN = 8K;
 

boards/layout_opentitan.ld → boards/layout_opentitan.ld.handlebars

@@ -17,7 +17,7 @@ MEMORY {
  * Any change to STACK_SIZE should be accompanied by a corresponding change to
  * `elf2tab`'s `--stack` option
  */
-STACK_SIZE = 2048;
+STACK_SIZE = {{stack_size}};
 
 MPU_MIN_ALIGN = 1K;
 

build.rs

@@ -1,12 +1,15 @@
 use std::env;
 use std::fs;
 use std::fs::File;
+use std::io::prelude::*;
 use std::io::BufRead;
 use std::io::BufReader;
 use std::path::Path;
 use std::process;
 
 static LAYOUT_FILE_NAME: &str = "layout.ld";
+static APP_STACK_SIZE: &str = "APP_STACK_SIZE";
+static DEFAULT_STACK_SIZE_BYTES: &str = "2048";
 
 fn main() {
     static PLATFORM_ENV_VAR: &str = "PLATFORM";
@@ -16,15 +19,28 @@ fn main() {
 
     println!("cargo:rerun-if-env-changed={}", PLATFORM_ENV_VAR);
     println!("cargo:rerun-if-env-changed={}", APP_HEAP_SIZE);
+    println!("cargo:rerun-if-env-changed={}", APP_STACK_SIZE);
     println!("cargo:rerun-if-env-changed={}", KERNEL_HEAP_SIZE);
     println!("cargo:rerun-if-changed={}", PLATFORM_FILE_NAME);
     println!("cargo:rerun-if-changed={}", LAYOUT_FILE_NAME);
 
+    let stack_size = read_env_var(APP_STACK_SIZE);
+    if stack_size.is_none() {
+        println!(
+            "cargo:warning=No explicit stack size specified. \
+             Using default of 2048 bytes. \
+             Set this explicitly using the \
+             environment variable {}.
+             ",
+            APP_STACK_SIZE
+        );
+    }
+
     let platform_name =
         read_env_var(PLATFORM_ENV_VAR).or_else(|| read_board_name_from_file(PLATFORM_FILE_NAME));
     if let Some(platform_name) = platform_name {
         println!("cargo:rustc-env={}={}", PLATFORM_ENV_VAR, platform_name);
-        copy_linker_file(platform_name.trim());
+        create_linker_file(platform_name.trim(), stack_size);
     } else {
         println!(
             "cargo:warning=No platform specified. \
@@ -34,13 +50,14 @@ fn main() {
 
     set_default_env(APP_HEAP_SIZE, "1024");
     set_default_env(KERNEL_HEAP_SIZE, "1024");
+    set_default_env(APP_STACK_SIZE, DEFAULT_STACK_SIZE_BYTES);
 }
 
 fn set_default_env(env_var: &str, default: &str) {
     if let Some(s) = read_env_var(env_var) {
         println!("cargo:rustc-env={}={}", env_var, s);
     } else {
-        // Just use a default of 1024 if nothing is passed in
+        // Use the provided default value if nothing is passed in
         println!("cargo:rustc-env={}={}", env_var, default);
     }
 }
@@ -63,12 +80,30 @@ fn read_board_name_from_file(file_name: &str) -> Option<String> {
     Some(board_name)
 }
 
-fn copy_linker_file(platform_name: &str) {
-    let linker_file_name = format!("boards/layout_{}.ld", platform_name);
+fn create_linker_file(platform_name: &str, stack_size: Option<String>) {
+    let linker_file_name = format!("boards/layout_{}.ld.handlebars", platform_name);
+
     let path = Path::new(&linker_file_name);
     if !path.exists() {
-        println!("Cannot find layout file {:?}", path);
+        println!("Cannot find layout template file {:?}", path);
         process::exit(1);
     }
-    fs::copy(linker_file_name, LAYOUT_FILE_NAME).unwrap();
+
+    create_linker_file_from_template(
+        path,
+        &stack_size.unwrap_or_else(|| DEFAULT_STACK_SIZE_BYTES.to_string()),
+    )
+}
+
+fn create_linker_file_from_template(path: &Path, stack_size: &str) {
+    let mut linker_template = File::open(path).expect("Failed to open file.");
+    let mut template_content = String::new();
+    linker_template
+        .read_to_string(&mut template_content)
+        .expect("Could not read linke file to string.");
+
+    let processed_template = template_content.replace("{{stack_size}}", &stack_size);
+
+    let out_path = Path::new(LAYOUT_FILE_NAME);
+    fs::write(out_path, processed_template).expect("Failed to write linker file.");
 }

tools/flash.sh

@@ -48,7 +48,7 @@ tab_file_name="${libtock_target_path}.tab"
 mkdir -p "${libtock_target_path}"
 cp "$1" "${elf_file_name}"
 
-elf2tab -n "${artifact}" -o "${tab_file_name}" "${elf_file_name}" --stack 2048 --app-heap $APP_HEAP_SIZE --kernel-heap $KERNEL_HEAP_SIZE --protected-region-size=64
+elf2tab -n "${artifact}" -o "${tab_file_name}" "${elf_file_name}" --stack $APP_STACK_SIZE --app-heap $APP_HEAP_SIZE --kernel-heap $KERNEL_HEAP_SIZE --protected-region-size=64
 
 if [ $tockload == "n" ]; then
 	echo "Skipping flashing for platform \"${PLATFORM}\""