devcontainer: install gdb and enable .gdbinit (#69)

* devcontainer: install gdb and enable .gdbinit

* update README.md

* fix port of gdb

.devcontainer/Dockerfile

@@ -1,6 +1,6 @@
 FROM mcr.microsoft.com/devcontainers/rust:1-1-bookworm
 
-RUN apt-get update && apt-get install -y cmake
+RUN apt-get update && apt-get install -y cmake vim gdb
 
 ARG LLVM_URL=https://github.com/llvm/llvm-project/releases/download/llvmorg-15.0.0/clang+llvm-15.0.0-x86_64-linux-gnu-rhel-8.4.tar.xz
 ARG ZIG_VERSION=zig-linux-x86_64-0.14.0-dev.2540+f857bf72e
@@ -34,3 +34,10 @@ RUN apt-get update && \
 RUN curl -SL https://ziglang.org/builds/${ZIG_VERSION}.tar.xz \
     | tar -xJC /tmp \
     && mv /tmp/${ZIG_VERSION} /usr/bin/zig
+
+RUN mkdir -p /home/vscode/.config/gdb \
+    && echo "add-auto-load-safe-path /workspaces/mewz/.gdbinit" > /home/vscode/.config/gdb/gdbinit
+
+USER vscode
+
+WORKDIR /workspaces/mewz

README.md

@@ -67,13 +67,34 @@ To use file systems, specify the directory by `-Ddir=<path to dir>`. See [exampl
 > [!NOTE]
 > QEMU's port 1234 is mapped to localhost:1234.
 
-## Run integration tests
+
+## Development
+
+### GDB
+
+You can debug Mewz with GDB. When you run Mewz with QEMU, it listens on port 12345 for GDB. You can connect to it by just running GDB at the root of the repository as `.gdbinit` is already configured.
+
+```sh
+zig build -Dapp-obj=<path to the object file generated by Wasker> run
+# In another terminal
+gdb
+```
+
+`zig build debug` command prevent Mewz from booting up until GDB connects to it. This is useful when you want to debug the boot process.
+
+```sh
+zig build -Dapp-obj=<path to the object file generated by Wasker> debug
+# In another terminal
+gdb
+```
+
+### Run integration tests
 
 ```sh
 zig bulid -Dtest=true run
 ```
 
-### Current Status
+## Current Status
 
 
 |        Feature        |                                                Status                                                |

scripts/integration-test.sh

@@ -7,7 +7,7 @@ cd $REPO_ROOT
 mkdir -p build/test
 (stty -echo; sleep 4; (sleep 0.5; echo q) | telnet localhost 1234) &
 (sleep 2; curl localhost:1234) &
-./scripts/run-qemu.sh | tee build/test/output.txt
+./scripts/run-qemu.sh "$@" | tee build/test/output.txt
 
 if ! grep -q "Integration test passed" build/test/output.txt; then
   echo "Integration Test FAILED!!"

scripts/rewrite-kernel.sh

@@ -4,14 +4,17 @@ set -eux
 REPO_ROOT=$(git rev-parse --show-toplevel)
 cd $REPO_ROOT
 
-file_path="zig-out/bin/mewz.elf"
+src_path="zig-out/bin/mewz.elf"
+dest_path="zig-out/bin/mewz.qemu.elf"
 offset=18
 new_data="\x03\x00"
 data_size=2
 
-head -c $offset "$file_path" > temp_head
-tail -c +$((offset + 1 + data_size)) "$file_path" > temp_tail
+cp "$src_path" "$dest_path"
 
-cat temp_head <(echo -n -e "$new_data") temp_tail > "$file_path"
+head -c $offset "$dest_path" > temp_head
+tail -c +$((offset + 1 + data_size)) "$dest_path" > temp_tail
+
+cat temp_head <(echo -n -e "$new_data") temp_tail > "$dest_path"
 
 rm temp_head temp_tail

scripts/run-qemu.sh

@@ -6,7 +6,7 @@ cd $REPO_ROOT
 
 QEMU_ARGS=(
     "-kernel"
-    "zig-out/bin/mewz.elf"
+    "zig-out/bin/mewz.qemu.elf"
     "-cpu"
     "Icelake-Server"
     "-m"