Complete build system rehaul

Inspired by Linux, the top Makefile is more recursive and practically every
directory has its own sub-Makefile which builds or includes only code inside its
directory. This new system works beautifully with -B and parallel jobs, while
the previous one would in either case build the bootloader multiple times (and,
in the case of parallel jobs, cause weird sporadic build errors).

diff --git a/Makefile b/Makefile
index 5d8c1ebb6dba7518b570733a9d170f1eba2ecf37..993a455b631b63c0d082d7150a80de0394bff5b3 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -1,36 +1,22 @@
 export AS = yasm
-ASFLAGS = -g dwarf2 -f elf
 export CC = i686-elf-gcc
-QEMU = qemu-system-i386 -monitor stdio
-
+export QEMU = qemu-system-i386 -monitor stdio
 export GIT_REV = $(shell git describe --long HEAD)
-
-CFLAGS = -g -fgnu89-inline -Ikernel/include -Ikernel/include/arch/x86 -ffreestanding -DGIT_COMMIT=\"$(GIT_REV)\"
-
-KERNEL_OBJ = kernel/entry.o kernel/arch/x86/halt.o kernel/arch/x86/tty/tty.o kernel/drivers/irq/i8259a.o kernel/arch/x86/irq/idt.o kernel/arch/x86/irq/interrupt.o kernel/arch/x86/irq/stub.o kernel/kernel.o
-
-BOOTLOADER_OBJ = boot/x86/mbr boot/x86/vbr-fat32 boot/x86/stage3/LOADER.BIN boot/x86/stage3/loader.elf
+MAKEFLAGS += -rR
 
 default: kernel/kernel.elf bootloader
-
 all: default boot/x86/disk.img
-
-bootloader: $(BOOTLOADER_OBJ)
-
 run: all
        $(QEMU) boot/x86/disk.img
-
 debug: all
        $(QEMU) -s -S boot/x86/disk.img
 
-boot/x86/mbr: boot/x86/mbr.s
-boot/x86/vbr-fat32: boot/x86/vbr-fat32.s boot/x86/fat32/*.s 
-boot/x86/stage3/LOADER.BIN: boot/x86/stage3/*.s boot/x86/stage3/*.c boot/x86/fat32/*.s boot/x86/stage3/stage3.ld
-boot/x86/stage3/loader.elf: boot/x86/stage3/*.s boot/x86/stage3/*.c boot/x86/fat32/*.s boot/x86/stage3/stage3.ld
-$(BOOTLOADER_OBJ):
+kernel/kernel.elf:
+       $(MAKE) -C kernel
+bootloader:
        $(MAKE) -C boot/x86
 
-boot/x86/disk.img: boot/x86/mbr boot/x86/vbr-fat32 boot/x86/stage3/LOADER.BIN boot/x86/disk.dump kernel/kernel.elf
+boot/x86/disk.img: bootloader boot/x86/disk.dump kernel/kernel.elf
        truncate -s1G boot/x86/disk.img
        sfdisk boot/x86/disk.img < boot/x86/disk.dump
        mkfs.fat -F 32 --offset 2048 boot/x86/disk.img
@@ -39,14 +25,11 @@ boot/x86/disk.img: boot/x86/mbr boot/x86/vbr-fat32 boot/x86/stage3/LOADER.BIN bo
        mcopy -i boot/x86/disk.img@@1M boot/x86/stage3/LOADER.BIN ::.
        mcopy -i boot/x86/disk.img@@1M kernel/kernel.elf ::./KERNEL.ELF
 
-kernel/kernel.elf: $(KERNEL_OBJ)
-       $(CC) -ffreestanding -nostdlib -o $@ -T kernel/linker.ld ${KERNEL_OBJ} -lgcc
-       i686-elf-objcopy --only-keep-debug kernel/kernel.elf kernel/kernel.dbg
-       i686-elf-objcopy --add-gnu-debuglink=kernel/kernel.dbg kernel/kernel.elf
-       i686-elf-strip --strip-unneeded kernel/kernel.elf
-
 clean:
-       -rm kernel/kernel.{dbg,elf} ${KERNEL_OBJ}
-       cd boot/x86 && $(MAKE) clean
+       $(MAKE) -C boot/x86 clean
+       $(MAKE) -C kernel clean
 
-.PHONY: default all clean run debug bootloader
+# Even though kernel.elf is a real target, it's considered phony so that the
+# kernel Makefile is always run. We don't check is the kernel binary up-to-date
+# here because we want to be more recursive.
+.PHONY: default all clean run debug bootloader kernel/kernel.elf

diff --git a/boot/x86/Makefile b/boot/x86/Makefile
index e75e8dc23573c664b7cbeb8de2ab66ae69720b39..3d12d12cdd6c07799b3920de893e3bd476643c5e 100644 (file)
--- a/boot/x86/Makefile
+++ b/boot/x86/Makefile
@@ -1,27 +1,19 @@
-default: mbr vbr-fat32 stage3/LOADER.BIN stage3/loader.elf
+BOOTLOADER_OBJ = mbr vbr-fat32
+ASFLAGS_BASE = -w-zeroing
 
-CFLAGS=-g -ffreestanding -Istage3
-LD=i686-elf-gcc
-LDFLAGS=-T stage3/stage3.ld -ffreestanding -nostdlib -g
+default: $(BOOTLOADER_OBJ) stage3
 
-STAGE3_OBJ=stage3/loader.o stage3/paging.o stage3/elf.o stage3/prekernel.o
-
-mbr: mbr.s
-       $(AS) $(ASFLAGS) -w-zeroing -o $@ $<
+stage3:
+       $(MAKE) -C stage3
 
 vbr-fat32: vbr-fat32.s fat32/*.s
-       $(AS) $(ASFLAGS) -o $@ $<
-
-stage3/loader.elf: $(STAGE3_OBJ)
-       $(CC) $(LDFLAGS) -o $@ $^ -lgcc -Wl,--oformat=elf32-i386
-
-stage3/LOADER.BIN: $(STAGE3_OBJ)
-       $(CC) $(LDFLAGS) -o $@ $^ -lgcc
-
-stage3/loader.o: stage3/loader.s stage3/*.s
-       $(AS) $(ASFLAGS) -f elf -g dwarf2 -DGIT_REVISION=\"$(GIT_REV)\" -o $@ $<
 
 clean:
-       -rm mbr vbr-fat32 stage3/LOADER.BIN stage3/loader.elf $(STAGE3_OBJ) disk.img
+       -rm mbr vbr-fat32 disk.img
+       $(MAKE) -C stage3 clean
+
+# Implicit rules
+%: %.s
+       $(AS) $(ASFLAGS_BASE) -f bin $< -o $@
 
-.PHONY : default clean
+.PHONY : default clean stage3

diff --git a/boot/x86/stage3/Makefile b/boot/x86/stage3/Makefile
new file mode 100644 (file)
index 0000000..c9622b2
--- /dev/null
+++ b/boot/x86/stage3/Makefile
@@ -0,0 +1,25 @@
+STAGE3_OBJ = loader.o elf.o paging.o prekernel.o
+
+ASFLAGS_BASE = -f elf -g dwarf2 -DGIT_REVISION=\"$(GIT_REV)\"
+CFLAGS_BASE = -ffreestanding -nostdlib -DGIT_REVISION=\"$(GIT_REV)\" -g
+LDFLAGS_BASE = -ffreestanding -nostdlib -g -lgcc -T stage3.ld
+
+default: LOADER.BIN loader.elf
+
+loader.elf: $(STAGE3_OBJ)
+       $(CC) $(LDFLAGS_BASE) $(LDFLAGS) -Wl,--oformat=elf32-i386 $^ -o $@
+
+LOADER.BIN: $(STAGE3_OBJ)
+       $(CC) $(LDFLAGS_BASE) $(LDFLAGS) $^ -o $@
+
+# Implicit rules
+%.o: %.c
+       $(CC) $(CFLAGS_BASE) $(CFLAGS) -c $< -o $@
+
+%.o: %.s
+       $(AS) $(ASFLAGS_BASE) $(ASFLAGS) $< -o $@
+
+clean:
+       -rm -f $(STAGE3_OBJ) LOADER.BIN loader.elf
+
+.PHONY: default clean

diff --git a/boot/x86/stage3/elf.c b/boot/x86/stage3/elf.c
index d3d215ffa71fbcfca830e64c75c5ed15383cc597..8621c39f7689b8b5c3336661796bde5dcf28187c 100644 (file)
--- a/boot/x86/stage3/elf.c
+++ b/boot/x86/stage3/elf.c
@@ -1,7 +1,7 @@
 /* Code for parsing ELF binaries (the kernel) */
 
-#include <elf.h>
-#include <paging.h>
+#include "elf.h"
+#include "paging.h"
 #include <stdint.h>
 
 int check_elf_header(struct elf_header *header)

diff --git a/boot/x86/stage3/paging.c b/boot/x86/stage3/paging.c
index 5a0e5f707db9806fcf84a69930da23810f2369f2..14afe85b84174af78356419a8d1ddb907612069c 100644 (file)
--- a/boot/x86/stage3/paging.c
+++ b/boot/x86/stage3/paging.c
@@ -1,7 +1,7 @@
 /* Code for enabling paging */
 
 #include <stdint.h>
-#include <paging.h>
+#include "paging.h"
 
 /* Preallocated page tables. */
 static uint32_t page_directory[1024] __attribute__((aligned(4096))) __attribute__((section(".data")));

diff --git a/boot/x86/stage3/prekernel.c b/boot/x86/stage3/prekernel.c
index 280c35079da019c3a814bf602f401307645990fe..07bd7215abad42fa310927e5579dcd765f7134be 100644 (file)
--- a/boot/x86/stage3/prekernel.c
+++ b/boot/x86/stage3/prekernel.c
@@ -1,5 +1,5 @@
-#include <elf.h>
-#include <paging.h>
+#include "elf.h"
+#include "paging.h"
 
 /* This bit of code will be run right after the segment registers have been set
  * up for protected mode. */

diff --git a/boot/x86/stage3/stage3.ld b/boot/x86/stage3/stage3.ld
index 1accdc09b77ae0cee9b454004e25892fd0f0f5f7..e8bb5e791a407fccb68a07d91019a20cb518ab36 100644 (file)
--- a/boot/x86/stage3/stage3.ld
+++ b/boot/x86/stage3/stage3.ld
@@ -4,7 +4,7 @@ OUTPUT_FORMAT(binary)
 SECTIONS {
        . = 0x1800;
        .text : {
-               stage3/loader.o(.text)
+               loader.o(.text)
                *(.text)
        }
        .rodata : { *(.rodata) }

diff --git a/kernel/Makefile b/kernel/Makefile
new file mode 100644 (file)
index 0000000..a872ca6
--- /dev/null
+++ b/kernel/Makefile
@@ -0,0 +1,26 @@
+KERNEL_OBJ = kernel.o entry.o
+
+include drivers/Makefile
+include arch/x86/Makefile
+
+ASFLAGS_BASE = -f elf -g dwarf2
+CFLAGS_BASE = -fgnu89-inline -ffreestanding -nostdlib -Iinclude -Iinclude/arch/x86 -g -DGIT_COMMIT=\"$(GIT_REV)\"
+LDFLAGS_BASE = -ffreestanding -nostdlib -lgcc -g
+
+kernel.elf kernel.dbg: $(KERNEL_OBJ)
+       $(CC) $(LDFLAGS_BASE) $(LDFLAGS) -T linker.ld $^ -o $@
+       i686-elf-objcopy --only-keep-debug kernel.elf kernel.dbg
+       i686-elf-objcopy --add-gnu-debuglink=kernel.dbg kernel.elf
+       i686-elf-strip --strip-unneeded kernel.elf
+
+clean:
+       -rm $(KERNEL_OBJ) kernel.elf kernel.dbg
+
+# Implicit rules
+%.o: %.c
+       $(CC) $(CFLAGS_BASE) $(CFLAGS) -c $< -o $@
+
+%.o: %.s
+       $(AS) $(ASFLAGS_BASE) $(ASFLAGS) $< -o $@
+
+.PHONY: clean

diff --git a/kernel/arch/x86/Makefile b/kernel/arch/x86/Makefile
new file mode 100644 (file)
index 0000000..52224a3
--- /dev/null
+++ b/kernel/arch/x86/Makefile
@@ -0,0 +1,4 @@
+include arch/x86/irq/Makefile
+include arch/x86/tty/Makefile
+
+KERNEL_OBJ += arch/x86/halt.o

diff --git a/kernel/arch/x86/irq/Makefile b/kernel/arch/x86/irq/Makefile
new file mode 100644 (file)
index 0000000..3dc6f82
--- /dev/null
+++ b/kernel/arch/x86/irq/Makefile
@@ -0,0 +1 @@
+KERNEL_OBJ += $(addprefix arch/x86/irq/, idt.o interrupt.o stub.o)

diff --git a/kernel/arch/x86/tty/Makefile b/kernel/arch/x86/tty/Makefile
new file mode 100644 (file)
index 0000000..0498223
--- /dev/null
+++ b/kernel/arch/x86/tty/Makefile
@@ -0,0 +1 @@
+KERNEL_OBJ += arch/x86/tty/tty.o

diff --git a/kernel/drivers/Makefile b/kernel/drivers/Makefile
new file mode 100644 (file)
index 0000000..76d86aa
--- /dev/null
+++ b/kernel/drivers/Makefile
@@ -0,0 +1 @@
+include drivers/irq/Makefile

diff --git a/kernel/drivers/irq/Makefile b/kernel/drivers/irq/Makefile
new file mode 100644 (file)
index 0000000..cd5b834
--- /dev/null
+++ b/kernel/drivers/irq/Makefile
@@ -0,0 +1 @@
+KERNEL_OBJ += drivers/irq/i8259a.o

diff --git a/kernel/linker.ld b/kernel/linker.ld
index a6fb8e48ed2d2289fde99b19e8bb976ac75d004c..40870daa95a4735bf524150ef7df90ce41250bf0 100644 (file)
--- a/kernel/linker.ld
+++ b/kernel/linker.ld
@@ -7,7 +7,7 @@ SECTIONS
 
        .text : AT(ADDR(.text) - 0xbff00000) ALIGN(4K) {
                __TEXT_BASE__ = .;
-               kernel/entry.o (.text)
+               entry.o (.text)
                *(.text)
                __TEXT_END__ = .;
        }