Started implementing debugging facilities

.gitignore

@@ -169,3 +169,4 @@ $RECYCLE.BIN/
 build
 .clang-format
 .ccls-cache
+socks.log

Makefile

@@ -17,8 +17,9 @@ KERNEL_OBJ := $(addprefix $(BUILDDIR)/,$(KERNEL_C_FILES:.c=.o))
 
 BUILD_ID := $(shell tools/generate_build_id.py --arch $(ARCH))
 
-CFLAGS := -DBUILD_ID=\"$(BUILD_ID)\"
-ASMFLAGS := -DBUILD_ID=\"$(BUILD_ID)\"
+CFLAGS := $(CFLAGS) -DBUILD_ID=\"$(BUILD_ID)\" -g
+ASMFLAGS := $(ASMFLAGS) -DBUILD_ID=\"$(BUILD_ID)\"
+LDFLAGS := $(LDFLAGS) -g
 
 $(BUILDDIR)/$(KERNEL_EXEC): $(KERNEL_OBJ) $(ARCH_OBJ)
 	@echo "    \033[1;36mLINK\033[0m   \033[1m$@\033[0m"

arch/x86_64/extra.mk

@@ -1,4 +1,5 @@
 QEMU := qemu-system-x86_64
+QEMU_FLAGS := -m 64M -smp 4
 
 ARCH_TEMP_FILES := $(BUILDDIR)/$(KERNEL_EXEC).elf32
 
@@ -16,8 +17,13 @@ run: $(BUILDDIR)/$(KERNEL_EXEC) $(BUILDDIR)/$(KERNEL_EXEC).elf32
 	@$(QEMU) -kernel $(BUILDDIR)/$(KERNEL_EXEC).elf32
 
 debug: $(BUILDDIR)/$(KERNEL_EXEC) $(BUILDDIR)/$(KERNEL_EXEC).elf32
-	@echo "    \033[1;93mBOOT\033[0m   $<"
+	@echo "    \033[1;93mDEBUG\033[0m  $<"
+
+	@./tools/kernel-debug/debug_session.sh \
+		tools/kernel-debug/gdb_session_init \
+		tools/kernel-debug/lldb_session_init \
+		$(QEMU) \
+			-kernel $(BUILDDIR)/$(KERNEL_EXEC).elf32 -S -s \
+			-curses -serial file:socks.log $(QEMU_FLAGS)
+
 
-	@$(QEMU) \
-		-kernel $(BUILDDIR)/$(KERNEL_EXEC).elf32 -S -s \
-		-monitor stdio

arch/x86_64/start_32.S

@@ -55,7 +55,7 @@ bootstrap_pdpt:		# a single PDPT
 bootstrap_pdir_buf:	# a buffer of page directories. each pdir entry can be used to map 2MB of virtual memory.
 	.skip BOOTSTRAP_PDIR_SIZE
 bootstrap_stack_bottom:
-	.skip 0x1000
+	.skip 0x4000
 bootstrap_stack_top:
 
 /*******
@@ -260,7 +260,8 @@ long_mode_switch:
 _start:
 	mov $bootstrap_stack_top, %esp
 
-	push %ebx			# store the pointer to the multiboot info block.
+	push %ebx			# store the pointer to the multiboot info block as a 64-bit value.
+	push $0x00			# store the pointer to the multiboot info block as a 64-bit value.
 
 	# check if long mode is supported
 	movl $0x80000000, %eax		# Extended-function 80000000h.

arch/x86_64/start_64.S

@@ -1,5 +1,7 @@
 .code64
 
+.extern kernel_init			# defined in core/main.c
+
 .section .boot.rodata, "a", @progbits
 
 /*******
@@ -63,7 +65,11 @@ print_kernel_identifier:
 .type start_64, @function
 start_64:
 	call vga_clear
+
+	pop %rax
 	call print_kernel_identifier
 
+	call kernel_init
+
 	cli
 	hlt

core/main.c

@@ -1,4 +1,8 @@
-void kernel_init()
-{
+#include <stdint.h>
 
+void kernel_init(uint64_t arg)
+{
+	uint8_t *vga = (uint8_t *)0xb8000;
+	*vga = 'A';
+	*(vga + 1) = 0x0F;
 }

tools/kernel-debug/debug_session.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+import sys
+import os
+import subprocess
+import time
+import signal
+
+
+qemu_args = []
+gdb_args  = []
+cur_program = ''
+
+
+def run_process(args):
+    p = subprocess.Popen(args,
+            bufsize=1,
+            shell=True,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE)
+
+    while True:
+        retcode = p.poll()
+        line = p.stdout.read(1)
+        yield line
+        if retcode is not None:
+            break
+
+
+for arg in sys.argv[1:]:
+    if arg == '--qemu':
+        cur_program = 'qemu'
+        continue
+    elif arg == '--gdb':
+        cur_program = 'gdb'
+        continue
+
+    if cur_program == 'qemu':
+        qemu_args += [arg]
+    elif cur_program == 'gdb':
+        gdb_args += [arg]
+    else:
+        print('No program specified')
+        exit(-1)
+
+env = os.environ.copy()
+signal.signal(signal.SIGINT, signal.SIG_IGN)
+qemu = subprocess.Popen(qemu_args,
+        env=env,
+        start_new_session=True,
+        restore_signals=False)
+time.sleep(1)
+
+if qemu.poll() is not None:
+    print('Failed to start QEMU')
+    exit(-1)
+
+subprocess.run(gdb_args,
+        env=env,
+        stdout=sys.stdout,
+        stdin=sys.stdin,
+        stderr=sys.stderr)
+qemu.kill()

tools/kernel-debug/debug_session.sh

@@ -0,0 +1,26 @@
+#!/bin/bash
+
+gdb_cfg=$1
+lldb_cfg=$2
+shift 2
+
+if command -v gdb &> /dev/null; then
+	tmux \
+		new-session -d -s hz-debug "sleep 0.3; gdb -tui -x $gdb_cfg" \; \
+		split-window -h -l 80 \; \
+		split-window -v -l 25 "$@"\; \
+		select-pane -t 0
+elif command -v lldb &> /dev/null; then
+	tmux \
+		new-session -d -s hz-debug "sleep 0.1; lldb --source $lldb_cfg" \; \
+		split-window -h -l 80 \; \
+		split-window -v -l 25 "$@"\; \
+		select-pane -t 0
+else
+	echo "No debugger available"
+	exit -1
+fi
+
+tmux a -t hz-debug
+tmux kill-session -t hz-debug
+

tools/kernel-debug/gdb_session_init

@@ -0,0 +1,4 @@
+set confirm off
+symbol-file build/socks_kernel
+target remote localhost:1234
+set confirm on

tools/kernel-debug/lldb_session_init

@@ -0,0 +1,2 @@
+file build/socks_kernel
+gdb-remote localhost:1234

tools/make/gcc-cross-compile.mk

@@ -2,7 +2,7 @@ LD  := $(ARCH)-elf-gcc
 CC  := $(ARCH)-elf-gcc
 ASM := $(ARCH)-elf-gcc
 
-CFLAGS   := -nostdlib -nostdinc -ffreestanding -Wl,-nostdlib
+CFLAGS   := -ffreestanding -nostdlib
 ASMFLAGS := $(CFLAGS)
 LDFLAGS  := -nostdlib