QEMU debugging via LLDB or optionally GDB

This commit is contained in:
cowmonk 2025-07-21 14:10:43 -07:00
parent 4a304f7b63
commit 93abdf8dac
10 changed files with 77 additions and 7 deletions

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@ -1,22 +1,39 @@
all: iso
iso: kernel limine
@echo "Copying kernel to isodir..."
cp -v ./kernel/bin/cowos ./isodir/boot/
@echo "Creating ISO image..."
xorriso -as mkisofs -R -r -J -b boot/limine/limine-bios-cd.bin \
-no-emul-boot -boot-load-size 4 -boot-info-table -hfsplus \
-apm-block-size 2048 --efi-boot boot/limine/limine-uefi-cd.bin \
-efi-boot-part --efi-boot-image --protective-msdos-label \
isodir -o cowos.iso
@echo "Installing Limine BIOS..."
./limine/limine bios-install cowos.iso
kernel:
make -C ./kernel/ all
@echo "Buliding kernel..."
make -C ./kernel/
limine: kernel
@echo "Setting up Limine..."
./scripts/limine-git.sh
clean:
@echo "Cleaning up..."
rm cowos.iso
make -C ./kernel/ clean
run:
@echo "Running cowos in QEMU..."
@if [ "$(DEBUG)" = "1" ]; then \
echo "Debug mode: Starting QEMU with LLDB..."; \
qemu-system-x86_64 -cdrom cowos.iso -m 512M -serial stdio -s -S & \
echo "Launching LLDB..."; \
lldb --arch x86_64 -o "gdb-remote localhost:1234" ./kernel/bin/cowos; \
else \
qemu-system-x86_64 -cdrom cowos.iso -m 512M -serial stdio; \
fi
.PHONY: all iso kernel limine clean run

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@ -15,13 +15,41 @@ You'll need a few things:
- xorriso (iso creation)
- git
- make
### OPTIONAL:
- qemu (for virtual machine)
- LLDB (debugging purposes)
After acquiring those just run make and it'll do everything for you:
```bash
make
```
By default the kernel is compiled with debug symbols, if you would like to avoid this, you can simply override the CFLAGS:
```bash
cd kernel/ # it is recommended to go to the actual directory yourself
make CFLAGS="-s -O3 -pipe"
cd .. # return to root
make
```
Eventually in the future this will be changed to be something much more convienent, however for now the inclusion of debug symbols is nessacary for development.
## RUNNING
There is now a script to automate running cowos, although it's quite simple right now, this is important for the future as cowos will eventually require a root partition and other things as it grows to userspace slowly. To run, simply run this in the root of the repository:
```bash
make run # This will require qemu
```
For developers, running with the DEBUG flag will launch lldb with qemu to help debug issues with cowos:
```bash
make DEBUG=1 run
```
if you do not like LLDB, I included a script called `run-gdb` in the `scripts/` directory for the gdb fans out there. I personally want to keep this project as gnu-free as possible, since I want cowos to not be GNU/cowos, I want it to just be cowos. And this means that I will even avoid anything as simple as the debugger being used to be non-GNU. Run in the root like so:
```bash
./scripts/run-gdb
```
It will automatically exit qemu if gdb is exited, and by default gdb will run in tui mode.
# Credits
- [Limine](https://github.com/limine-bootloader/limine): modern, advanced, portable, multiprotocol bootloader and boot manager.

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@ -11,4 +11,8 @@ if [ ! -d ./limine/ ]; then
cp -v limine/BOOTX64.EFI isodir/EFI/BOOT/
cp -v limine/BOOTIA32.EFI isodir/EFI/BOOT/
else
echo "Limine is already setup! Skipping..."
fi

21
scripts/run-gdb Executable file
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@ -0,0 +1,21 @@
#!/bin/sh
echo "Starting QEMU with GDB server (localhost:1234)..."
qemu-system-x86_64 -cdrom cowos.iso -m 512M -serial stdio -s -S &
QEMU_PID=$!
sleep 1 # just in case so we let it cook
if ! ps -p $QEMU_PID > /dev/null; then
echo "Error: QEMU failed to start."
exit 1
fi
echo "Launching GDB in TUI mode..."
gdb --tui \
-ex "file ./kernel/bin/cowos" \
-ex "target remote localhost:1234" \
# kill QEMU when GDB exits
echo "GDB exited. Terminating QEMU..."
kill $QEMU_PID 2>/dev/null