From dcd3686d3705110720250babf9400aedecd401fd Mon Sep 17 00:00:00 2001
From: garenchan <1412950785@qq.com>
Date: Fri, 16 Nov 2018 10:47:11 +0800
Subject: [PATCH 1/3] Replace target file as $@ .

---
 14-checkpoint/Makefile       | 2 +-
 15-video-ports/Makefile      | 2 +-
 16-video-driver/Makefile     | 2 +-
 17-video-scroll/Makefile     | 2 +-
 18-interrupts/Makefile       | 2 +-
 19-interrupts-irqs/Makefile  | 2 +-
 20-interrupts-timer/Makefile | 2 +-
 21-shell/Makefile            | 2 +-
 22-malloc/Makefile           | 2 +-
 23-fixes/Makefile            | 2 +-
 10 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/14-checkpoint/Makefile b/14-checkpoint/Makefile
index b611257..45cc9e4 100644
--- a/14-checkpoint/Makefile
+++ b/14-checkpoint/Makefile
@@ -11,7 +11,7 @@ CFLAGS = -g
 
 # First rule is run by default
 os-image.bin: boot/bootsect.bin kernel.bin
-	cat $^ > os-image.bin
+	cat $^ > $@
 
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
diff --git a/15-video-ports/Makefile b/15-video-ports/Makefile
index b611257..45cc9e4 100644
--- a/15-video-ports/Makefile
+++ b/15-video-ports/Makefile
@@ -11,7 +11,7 @@ CFLAGS = -g
 
 # First rule is run by default
 os-image.bin: boot/bootsect.bin kernel.bin
-	cat $^ > os-image.bin
+	cat $^ > $@
 
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
diff --git a/16-video-driver/Makefile b/16-video-driver/Makefile
index b611257..45cc9e4 100644
--- a/16-video-driver/Makefile
+++ b/16-video-driver/Makefile
@@ -11,7 +11,7 @@ CFLAGS = -g
 
 # First rule is run by default
 os-image.bin: boot/bootsect.bin kernel.bin
-	cat $^ > os-image.bin
+	cat $^ > $@
 
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
diff --git a/17-video-scroll/Makefile b/17-video-scroll/Makefile
index b611257..45cc9e4 100644
--- a/17-video-scroll/Makefile
+++ b/17-video-scroll/Makefile
@@ -11,7 +11,7 @@ CFLAGS = -g
 
 # First rule is run by default
 os-image.bin: boot/bootsect.bin kernel.bin
-	cat $^ > os-image.bin
+	cat $^ > $@
 
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
diff --git a/18-interrupts/Makefile b/18-interrupts/Makefile
index 8a68aa0..d7e16c5 100644
--- a/18-interrupts/Makefile
+++ b/18-interrupts/Makefile
@@ -11,7 +11,7 @@ CFLAGS = -g
 
 # First rule is run by default
 os-image.bin: boot/bootsect.bin kernel.bin
-	cat $^ > os-image.bin
+	cat $^ > $@
 
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
diff --git a/19-interrupts-irqs/Makefile b/19-interrupts-irqs/Makefile
index 8a68aa0..d7e16c5 100644
--- a/19-interrupts-irqs/Makefile
+++ b/19-interrupts-irqs/Makefile
@@ -11,7 +11,7 @@ CFLAGS = -g
 
 # First rule is run by default
 os-image.bin: boot/bootsect.bin kernel.bin
-	cat $^ > os-image.bin
+	cat $^ > $@
 
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
diff --git a/20-interrupts-timer/Makefile b/20-interrupts-timer/Makefile
index 4d6da94..3abf8ce 100644
--- a/20-interrupts-timer/Makefile
+++ b/20-interrupts-timer/Makefile
@@ -11,7 +11,7 @@ CFLAGS = -g
 
 # First rule is run by default
 os-image.bin: boot/bootsect.bin kernel.bin
-	cat $^ > os-image.bin
+	cat $^ > $@
 
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
diff --git a/21-shell/Makefile b/21-shell/Makefile
index 1478294..b347fc8 100644
--- a/21-shell/Makefile
+++ b/21-shell/Makefile
@@ -12,7 +12,7 @@ CFLAGS = -g -m32 -nostdlib -nostdinc -fno-builtin -fno-stack-protector -nostartf
 
 # First rule is run by default
 os-image.bin: boot/bootsect.bin kernel.bin
-	cat $^ > os-image.bin
+	cat $^ > $@
 
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
diff --git a/22-malloc/Makefile b/22-malloc/Makefile
index 1478294..b347fc8 100644
--- a/22-malloc/Makefile
+++ b/22-malloc/Makefile
@@ -12,7 +12,7 @@ CFLAGS = -g -m32 -nostdlib -nostdinc -fno-builtin -fno-stack-protector -nostartf
 
 # First rule is run by default
 os-image.bin: boot/bootsect.bin kernel.bin
-	cat $^ > os-image.bin
+	cat $^ > $@
 
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
diff --git a/23-fixes/Makefile b/23-fixes/Makefile
index 65e577b..7c244b6 100644
--- a/23-fixes/Makefile
+++ b/23-fixes/Makefile
@@ -11,7 +11,7 @@ CFLAGS = -g -ffreestanding -Wall -Wextra -fno-exceptions -m32
 
 # First rule is run by default
 os-image.bin: boot/bootsect.bin kernel.bin
-	cat $^ > os-image.bin
+	cat $^ > $@
 
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case

From 02a77989c2d0ab155581f051b6344860146cdca5 Mon Sep 17 00:00:00 2001
From: garenchan <1412950785@qq.com>
Date: Fri, 16 Nov 2018 15:46:00 +0800
Subject: [PATCH 2/3] Use ld through global variable.

---
 14-checkpoint/Makefile       | 5 +++--
 15-video-ports/Makefile      | 5 +++--
 16-video-driver/Makefile     | 5 +++--
 17-video-scroll/Makefile     | 5 +++--
 18-interrupts/Makefile       | 5 +++--
 19-interrupts-irqs/Makefile  | 5 +++--
 20-interrupts-timer/Makefile | 5 +++--
 21-shell/Makefile            | 5 +++--
 22-malloc/Makefile           | 5 +++--
 23-fixes/Makefile            | 5 +++--
 10 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/14-checkpoint/Makefile b/14-checkpoint/Makefile
index 45cc9e4..5ff0d03 100644
--- a/14-checkpoint/Makefile
+++ b/14-checkpoint/Makefile
@@ -6,6 +6,7 @@ OBJ = ${C_SOURCES:.c=.o}
 # Change this if your cross-compiler is somewhere else
 CC = /usr/local/i386elfgcc/bin/i386-elf-gcc
 GDB = /usr/local/i386elfgcc/bin/i386-elf-gdb
+LD = /usr/local/i386elfgcc/bin/i386-elf-ld
 # -g: Use debugging symbols in gcc
 CFLAGS = -g
 
@@ -16,11 +17,11 @@ os-image.bin: boot/bootsect.bin kernel.bin
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
 kernel.bin: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ --oformat binary
+	${LD} -o $@ -Ttext 0x1000 $^ --oformat binary
 
 # Used for debugging purposes
 kernel.elf: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ 
+	${LD} -o $@ -Ttext 0x1000 $^
 
 run: os-image.bin
 	qemu-system-i386 -fda os-image.bin
diff --git a/15-video-ports/Makefile b/15-video-ports/Makefile
index 45cc9e4..5ff0d03 100644
--- a/15-video-ports/Makefile
+++ b/15-video-ports/Makefile
@@ -6,6 +6,7 @@ OBJ = ${C_SOURCES:.c=.o}
 # Change this if your cross-compiler is somewhere else
 CC = /usr/local/i386elfgcc/bin/i386-elf-gcc
 GDB = /usr/local/i386elfgcc/bin/i386-elf-gdb
+LD = /usr/local/i386elfgcc/bin/i386-elf-ld
 # -g: Use debugging symbols in gcc
 CFLAGS = -g
 
@@ -16,11 +17,11 @@ os-image.bin: boot/bootsect.bin kernel.bin
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
 kernel.bin: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ --oformat binary
+	${LD} -o $@ -Ttext 0x1000 $^ --oformat binary
 
 # Used for debugging purposes
 kernel.elf: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ 
+	${LD} -o $@ -Ttext 0x1000 $^
 
 run: os-image.bin
 	qemu-system-i386 -fda os-image.bin
diff --git a/16-video-driver/Makefile b/16-video-driver/Makefile
index 45cc9e4..5ff0d03 100644
--- a/16-video-driver/Makefile
+++ b/16-video-driver/Makefile
@@ -6,6 +6,7 @@ OBJ = ${C_SOURCES:.c=.o}
 # Change this if your cross-compiler is somewhere else
 CC = /usr/local/i386elfgcc/bin/i386-elf-gcc
 GDB = /usr/local/i386elfgcc/bin/i386-elf-gdb
+LD = /usr/local/i386elfgcc/bin/i386-elf-ld
 # -g: Use debugging symbols in gcc
 CFLAGS = -g
 
@@ -16,11 +17,11 @@ os-image.bin: boot/bootsect.bin kernel.bin
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
 kernel.bin: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ --oformat binary
+	${LD} -o $@ -Ttext 0x1000 $^ --oformat binary
 
 # Used for debugging purposes
 kernel.elf: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ 
+	${LD} -o $@ -Ttext 0x1000 $^
 
 run: os-image.bin
 	qemu-system-i386 -fda os-image.bin
diff --git a/17-video-scroll/Makefile b/17-video-scroll/Makefile
index 45cc9e4..5ff0d03 100644
--- a/17-video-scroll/Makefile
+++ b/17-video-scroll/Makefile
@@ -6,6 +6,7 @@ OBJ = ${C_SOURCES:.c=.o}
 # Change this if your cross-compiler is somewhere else
 CC = /usr/local/i386elfgcc/bin/i386-elf-gcc
 GDB = /usr/local/i386elfgcc/bin/i386-elf-gdb
+LD = /usr/local/i386elfgcc/bin/i386-elf-ld
 # -g: Use debugging symbols in gcc
 CFLAGS = -g
 
@@ -16,11 +17,11 @@ os-image.bin: boot/bootsect.bin kernel.bin
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
 kernel.bin: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ --oformat binary
+	${LD} -o $@ -Ttext 0x1000 $^ --oformat binary
 
 # Used for debugging purposes
 kernel.elf: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ 
+	${LD} -o $@ -Ttext 0x1000 $^
 
 run: os-image.bin
 	qemu-system-i386 -fda os-image.bin
diff --git a/18-interrupts/Makefile b/18-interrupts/Makefile
index d7e16c5..fd48e28 100644
--- a/18-interrupts/Makefile
+++ b/18-interrupts/Makefile
@@ -6,6 +6,7 @@ OBJ = ${C_SOURCES:.c=.o cpu/interrupt.o}
 # Change this if your cross-compiler is somewhere else
 CC = /usr/local/i386elfgcc/bin/i386-elf-gcc
 GDB = /usr/local/i386elfgcc/bin/i386-elf-gdb
+LD = /usr/local/i386elfgcc/bin/i386-elf-ld
 # -g: Use debugging symbols in gcc
 CFLAGS = -g
 
@@ -16,11 +17,11 @@ os-image.bin: boot/bootsect.bin kernel.bin
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
 kernel.bin: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ --oformat binary
+	${LD} -o $@ -Ttext 0x1000 $^ --oformat binary
 
 # Used for debugging purposes
 kernel.elf: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ 
+	${LD} -o $@ -Ttext 0x1000 $^
 
 run: os-image.bin
 	qemu-system-i386 -fda os-image.bin
diff --git a/19-interrupts-irqs/Makefile b/19-interrupts-irqs/Makefile
index d7e16c5..fd48e28 100644
--- a/19-interrupts-irqs/Makefile
+++ b/19-interrupts-irqs/Makefile
@@ -6,6 +6,7 @@ OBJ = ${C_SOURCES:.c=.o cpu/interrupt.o}
 # Change this if your cross-compiler is somewhere else
 CC = /usr/local/i386elfgcc/bin/i386-elf-gcc
 GDB = /usr/local/i386elfgcc/bin/i386-elf-gdb
+LD = /usr/local/i386elfgcc/bin/i386-elf-ld
 # -g: Use debugging symbols in gcc
 CFLAGS = -g
 
@@ -16,11 +17,11 @@ os-image.bin: boot/bootsect.bin kernel.bin
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
 kernel.bin: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ --oformat binary
+	${LD} -o $@ -Ttext 0x1000 $^ --oformat binary
 
 # Used for debugging purposes
 kernel.elf: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ 
+	${LD} -o $@ -Ttext 0x1000 $^
 
 run: os-image.bin
 	qemu-system-i386 -fda os-image.bin
diff --git a/20-interrupts-timer/Makefile b/20-interrupts-timer/Makefile
index 3abf8ce..d1922a7 100644
--- a/20-interrupts-timer/Makefile
+++ b/20-interrupts-timer/Makefile
@@ -6,6 +6,7 @@ OBJ = ${C_SOURCES:.c=.o cpu/interrupt.o}
 # Change this if your cross-compiler is somewhere else
 CC = /usr/local/i386elfgcc/bin/i386-elf-gcc
 GDB = /usr/local/i386elfgcc/bin/i386-elf-gdb
+LD = /usr/local/i386elfgcc/bin/i386-elf-ld
 # -g: Use debugging symbols in gcc
 CFLAGS = -g 
 
@@ -16,11 +17,11 @@ os-image.bin: boot/bootsect.bin kernel.bin
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
 kernel.bin: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ --oformat binary
+	${LD} -o $@ -Ttext 0x1000 $^ --oformat binary
 
 # Used for debugging purposes
 kernel.elf: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ 
+	${LD} -o $@ -Ttext 0x1000 $^
 
 run: os-image.bin
 	qemu-system-i386 -fda os-image.bin
diff --git a/21-shell/Makefile b/21-shell/Makefile
index b347fc8..23e9d9a 100644
--- a/21-shell/Makefile
+++ b/21-shell/Makefile
@@ -6,6 +6,7 @@ OBJ = ${C_SOURCES:.c=.o cpu/interrupt.o}
 # Change this if your cross-compiler is somewhere else
 CC = /usr/local/i386elfgcc/bin/i386-elf-gcc
 GDB = /usr/local/i386elfgcc/bin/i386-elf-gdb
+LD = /usr/local/i386elfgcc/bin/i386-elf-ld
 # -g: Use debugging symbols in gcc
 CFLAGS = -g -m32 -nostdlib -nostdinc -fno-builtin -fno-stack-protector -nostartfiles -nodefaultlibs \
 		 -Wall -Wextra -Werror
@@ -17,11 +18,11 @@ os-image.bin: boot/bootsect.bin kernel.bin
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
 kernel.bin: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ --oformat binary
+	${LD} -o $@ -Ttext 0x1000 $^ --oformat binary
 
 # Used for debugging purposes
 kernel.elf: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ 
+	${LD} -o $@ -Ttext 0x1000 $^
 
 run: os-image.bin
 	qemu-system-i386 -fda os-image.bin
diff --git a/22-malloc/Makefile b/22-malloc/Makefile
index b347fc8..23e9d9a 100644
--- a/22-malloc/Makefile
+++ b/22-malloc/Makefile
@@ -6,6 +6,7 @@ OBJ = ${C_SOURCES:.c=.o cpu/interrupt.o}
 # Change this if your cross-compiler is somewhere else
 CC = /usr/local/i386elfgcc/bin/i386-elf-gcc
 GDB = /usr/local/i386elfgcc/bin/i386-elf-gdb
+LD = /usr/local/i386elfgcc/bin/i386-elf-ld
 # -g: Use debugging symbols in gcc
 CFLAGS = -g -m32 -nostdlib -nostdinc -fno-builtin -fno-stack-protector -nostartfiles -nodefaultlibs \
 		 -Wall -Wextra -Werror
@@ -17,11 +18,11 @@ os-image.bin: boot/bootsect.bin kernel.bin
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
 kernel.bin: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ --oformat binary
+	${LD} -o $@ -Ttext 0x1000 $^ --oformat binary
 
 # Used for debugging purposes
 kernel.elf: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ 
+	${LD} -o $@ -Ttext 0x1000 $^
 
 run: os-image.bin
 	qemu-system-i386 -fda os-image.bin
diff --git a/23-fixes/Makefile b/23-fixes/Makefile
index 7c244b6..a678f60 100644
--- a/23-fixes/Makefile
+++ b/23-fixes/Makefile
@@ -6,6 +6,7 @@ OBJ = ${C_SOURCES:.c=.o cpu/interrupt.o}
 # Change this if your cross-compiler is somewhere else
 CC = /usr/local/i386elfgcc/bin/i386-elf-gcc
 GDB = /usr/local/i386elfgcc/bin/i386-elf-gdb
+LD = /usr/local/i386elfgcc/bin/i386-elf-ld
 # -g: Use debugging symbols in gcc
 CFLAGS = -g -ffreestanding -Wall -Wextra -fno-exceptions -m32
 
@@ -16,11 +17,11 @@ os-image.bin: boot/bootsect.bin kernel.bin
 # '--oformat binary' deletes all symbols as a collateral, so we don't need
 # to 'strip' them manually on this case
 kernel.bin: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ --oformat binary
+	${LD} -o $@ -Ttext 0x1000 $^ --oformat binary
 
 # Used for debugging purposes
 kernel.elf: boot/kernel_entry.o ${OBJ}
-	i386-elf-ld -o $@ -Ttext 0x1000 $^ 
+	${LD} -o $@ -Ttext 0x1000 $^ 
 
 run: os-image.bin
 	qemu-system-i386 -fda os-image.bin

From d7469c76b3e45e93d0894838c3bba57b4c7fff92 Mon Sep 17 00:00:00 2001
From: garenchan <1412950785@qq.com>
Date: Fri, 16 Nov 2018 15:49:01 +0800
Subject: [PATCH 3/3] Freeze CPU at qemu startup while debug. If we don't, the
 kernel might run into the infinite loop before GDB connects to Qemu.

---
 14-checkpoint/Makefile       | 2 +-
 15-video-ports/Makefile      | 2 +-
 16-video-driver/Makefile     | 2 +-
 17-video-scroll/Makefile     | 2 +-
 18-interrupts/Makefile       | 2 +-
 19-interrupts-irqs/Makefile  | 2 +-
 20-interrupts-timer/Makefile | 2 +-
 21-shell/Makefile            | 2 +-
 22-malloc/Makefile           | 2 +-
 23-fixes/Makefile            | 2 +-
 10 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/14-checkpoint/Makefile b/14-checkpoint/Makefile
index 5ff0d03..37e7ec9 100644
--- a/14-checkpoint/Makefile
+++ b/14-checkpoint/Makefile
@@ -28,7 +28,7 @@ run: os-image.bin
 
 # Open the connection to qemu and load our kernel-object file with symbols
 debug: os-image.bin kernel.elf
-	qemu-system-i386 -s -fda os-image.bin &
+	qemu-system-i386 -s -S -fda os-image.bin &
 	${GDB} -ex "target remote localhost:1234" -ex "symbol-file kernel.elf"
 
 # Generic rules for wildcards
diff --git a/15-video-ports/Makefile b/15-video-ports/Makefile
index 5ff0d03..37e7ec9 100644
--- a/15-video-ports/Makefile
+++ b/15-video-ports/Makefile
@@ -28,7 +28,7 @@ run: os-image.bin
 
 # Open the connection to qemu and load our kernel-object file with symbols
 debug: os-image.bin kernel.elf
-	qemu-system-i386 -s -fda os-image.bin &
+	qemu-system-i386 -s -S -fda os-image.bin &
 	${GDB} -ex "target remote localhost:1234" -ex "symbol-file kernel.elf"
 
 # Generic rules for wildcards
diff --git a/16-video-driver/Makefile b/16-video-driver/Makefile
index 5ff0d03..37e7ec9 100644
--- a/16-video-driver/Makefile
+++ b/16-video-driver/Makefile
@@ -28,7 +28,7 @@ run: os-image.bin
 
 # Open the connection to qemu and load our kernel-object file with symbols
 debug: os-image.bin kernel.elf
-	qemu-system-i386 -s -fda os-image.bin &
+	qemu-system-i386 -s -S -fda os-image.bin &
 	${GDB} -ex "target remote localhost:1234" -ex "symbol-file kernel.elf"
 
 # Generic rules for wildcards
diff --git a/17-video-scroll/Makefile b/17-video-scroll/Makefile
index 5ff0d03..37e7ec9 100644
--- a/17-video-scroll/Makefile
+++ b/17-video-scroll/Makefile
@@ -28,7 +28,7 @@ run: os-image.bin
 
 # Open the connection to qemu and load our kernel-object file with symbols
 debug: os-image.bin kernel.elf
-	qemu-system-i386 -s -fda os-image.bin &
+	qemu-system-i386 -s -S -fda os-image.bin &
 	${GDB} -ex "target remote localhost:1234" -ex "symbol-file kernel.elf"
 
 # Generic rules for wildcards
diff --git a/18-interrupts/Makefile b/18-interrupts/Makefile
index fd48e28..deccb84 100644
--- a/18-interrupts/Makefile
+++ b/18-interrupts/Makefile
@@ -28,7 +28,7 @@ run: os-image.bin
 
 # Open the connection to qemu and load our kernel-object file with symbols
 debug: os-image.bin kernel.elf
-	qemu-system-i386 -s -fda os-image.bin -d guest_errors,int &
+	qemu-system-i386 -s -S -fda os-image.bin -d guest_errors,int &
 	${GDB} -ex "target remote localhost:1234" -ex "symbol-file kernel.elf"
 
 # Generic rules for wildcards
diff --git a/19-interrupts-irqs/Makefile b/19-interrupts-irqs/Makefile
index fd48e28..deccb84 100644
--- a/19-interrupts-irqs/Makefile
+++ b/19-interrupts-irqs/Makefile
@@ -28,7 +28,7 @@ run: os-image.bin
 
 # Open the connection to qemu and load our kernel-object file with symbols
 debug: os-image.bin kernel.elf
-	qemu-system-i386 -s -fda os-image.bin -d guest_errors,int &
+	qemu-system-i386 -s -S -fda os-image.bin -d guest_errors,int &
 	${GDB} -ex "target remote localhost:1234" -ex "symbol-file kernel.elf"
 
 # Generic rules for wildcards
diff --git a/20-interrupts-timer/Makefile b/20-interrupts-timer/Makefile
index d1922a7..30c4edb 100644
--- a/20-interrupts-timer/Makefile
+++ b/20-interrupts-timer/Makefile
@@ -28,7 +28,7 @@ run: os-image.bin
 
 # Open the connection to qemu and load our kernel-object file with symbols
 debug: os-image.bin kernel.elf
-	qemu-system-i386 -s -fda os-image.bin -d guest_errors,int &
+	qemu-system-i386 -s -S -fda os-image.bin -d guest_errors,int &
 	${GDB} -ex "target remote localhost:1234" -ex "symbol-file kernel.elf"
 
 # Generic rules for wildcards
diff --git a/21-shell/Makefile b/21-shell/Makefile
index 23e9d9a..380bed4 100644
--- a/21-shell/Makefile
+++ b/21-shell/Makefile
@@ -29,7 +29,7 @@ run: os-image.bin
 
 # Open the connection to qemu and load our kernel-object file with symbols
 debug: os-image.bin kernel.elf
-	qemu-system-i386 -s -fda os-image.bin -d guest_errors,int &
+	qemu-system-i386 -s -S -fda os-image.bin -d guest_errors,int &
 	${GDB} -ex "target remote localhost:1234" -ex "symbol-file kernel.elf"
 
 # Generic rules for wildcards
diff --git a/22-malloc/Makefile b/22-malloc/Makefile
index 23e9d9a..380bed4 100644
--- a/22-malloc/Makefile
+++ b/22-malloc/Makefile
@@ -29,7 +29,7 @@ run: os-image.bin
 
 # Open the connection to qemu and load our kernel-object file with symbols
 debug: os-image.bin kernel.elf
-	qemu-system-i386 -s -fda os-image.bin -d guest_errors,int &
+	qemu-system-i386 -s -S -fda os-image.bin -d guest_errors,int &
 	${GDB} -ex "target remote localhost:1234" -ex "symbol-file kernel.elf"
 
 # Generic rules for wildcards
diff --git a/23-fixes/Makefile b/23-fixes/Makefile
index a678f60..53fdedf 100644
--- a/23-fixes/Makefile
+++ b/23-fixes/Makefile
@@ -28,7 +28,7 @@ run: os-image.bin
 
 # Open the connection to qemu and load our kernel-object file with symbols
 debug: os-image.bin kernel.elf
-	qemu-system-i386 -s -fda os-image.bin -d guest_errors,int &
+	qemu-system-i386 -s -S -fda os-image.bin -d guest_errors,int &
 	${GDB} -ex "target remote localhost:1234" -ex "symbol-file kernel.elf"
 
 # Generic rules for wildcards