Docs: Added architecture addition guide to README.md

I also made very minor changes in the build.sh to make it easier to add
new architectures.

Author: guyush1

README.md

@@ -135,6 +135,25 @@ The resulting binary will be placed in the `build/artifacts/` directory.
 
 </details>
 
+<details open>
+<summary>
+Adding a custom architecture
+</summary> <br />
+
+Adding a new architecture to the build system is straightforward. Follow these steps:
+
+- **Add a cross compiler**: <br />
+Add a musl-based compiler to the `ARCHS` dictionary in `src/docker_utils/download_musl_toolchains.py`. You can find musl-based compilers [here](https://more.musl.cc/). <br />
+If a musl-based compiler is not available for your architecture, you can instead install a compiler via `apt` in the Dockerfile. However, using a musl-based toolchain is highly recommended.
+- **Update the Makefile**: <br />
+Add the new architecture to the `ARCHS` variable in the Makefile.
+- **Modify `build.sh`**: <br />
+Locate the `set_compilation_variables` function in `build.sh`.
+  - Add the new architecture to the `supported_archs` variable (in the same way as in the Makefile).
+  - Add a new `if` branch to check for the new architecture, and within it, export the appropriate `HOST` variable using the compiler's target triple.
+
+</details>
+
 <a name="contributing_anchor"></a>
 ## Contributing
 

src/compilation/build.sh

@@ -8,7 +8,7 @@ source "$script_dir/full_build_conf.sh"
 # Don't want random unknown things to fail in the build procecss!
 set -e
 
-function set_compliation_variables() {
+function set_compilation_variables() {
     # Set compilation variables such as which compiler to use.
     #
     # Parameters:
@@ -29,25 +29,21 @@ function set_compliation_variables() {
     >&2 fancy_title "Setting compilation variables for $target_arch"
 
     if [[ "$target_arch" == "arm" ]]; then
-        CROSS=arm-linux-musleabi-
         export HOST=arm-linux-musleabi
     elif [[ "$target_arch" == "aarch64" ]]; then
-        CROSS=aarch64-linux-musl-
         export HOST=aarch64-linux-musl
     elif [[ "$target_arch" == "powerpc" ]]; then
-        CROSS=powerpc-linux-musl-
         export HOST=powerpc-linux-musl
     elif [[ "$target_arch" == "mips" ]]; then
-        CROSS=mips-linux-musl-
         export HOST=mips-linux-musl
     elif [[ "$target_arch" == "mipsel" ]]; then
-        CROSS=mipsel-linux-musl-
         export HOST=mipsel-linux-musl
     elif [[ "$target_arch" == "x86_64" ]]; then
-        CROSS=x86_64-linux-musl-
         export HOST=x86_64-linux-musl
     fi
 
+    CROSS="${HOST}-"
+
     export CC="${CROSS}gcc"
     export CXX="${CROSS}g++"
 
@@ -790,7 +786,7 @@ function build_gdb_with_dependencies() {
     local packages_dir="$build_dir/packages"
     local artifacts_dir="$build_dir/artifacts"
 
-    set_compliation_variables "$target_arch"
+    set_compilation_variables "$target_arch"
     if [[ $? -ne 0 ]]; then
         return 1
     fi