From ac82b7e5cc3e6d410aa9a0167f43b6b3b8c14452 Mon Sep 17 00:00:00 2001
From: mintsuki <mintsuki@protonmail.com>
Date: Wed, 15 Jun 2022 21:44:21 +0200
Subject: [PATCH] Make build more portable
---
.gitignore | 2 +-
GNUmakefile | 31 ++++++++++++++++++++-----------
README.md | 4 ++--
kernel/GNUmakefile | 34 ++++++++++++++++++++++++----------
kernel/linker.ld | 4 ----
5 files changed, 47 insertions(+), 28 deletions(-)
diff --git a/.gitignore b/.gitignore
index ebec950..fd3cdca 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,5 @@
limine
-ovmf-x64
+ovmf-X64
kernel/limine.h
*.elf
*.iso
diff --git a/GNUmakefile b/GNUmakefile
index ccec474..96e1602 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -1,3 +1,12 @@
+ARCH ?= x86_64
+
+# Check that the architecture is supported and set relevant variables.
+ifeq ($(ARCH),x86_64)
+ override EFI_ARCH := X64
+else
+ $(error Architecture $(ARCH) not supported)
+endif
+
.PHONY: all
all: barebones.iso
@@ -6,23 +15,23 @@ all-hdd: barebones.hdd
.PHONY: run
run: barebones.iso
- qemu-system-x86_64 -M q35 -m 2G -cdrom barebones.iso -boot d
+ qemu-system-$(ARCH) -M q35 -m 2G -cdrom barebones.iso -boot d
.PHONY: run-uefi
-run-uefi: ovmf-x64 barebones.iso
- qemu-system-x86_64 -M q35 -m 2G -bios ovmf-x64/OVMF.fd -cdrom barebones.iso -boot d
+run-uefi: ovmf-$(EFI_ARCH) barebones.iso
+ qemu-system-$(ARCH) -M q35 -m 2G -bios ovmf-$(EFI_ARCH)/OVMF.fd -cdrom barebones.iso -boot d
.PHONY: run-hdd
run-hdd: barebones.hdd
- qemu-system-x86_64 -M q35 -m 2G -hda barebones.hdd
+ qemu-system-$(ARCH) -M q35 -m 2G -hda barebones.hdd
.PHONY: run-hdd-uefi
-run-hdd-uefi: ovmf-x64 barebones.hdd
- qemu-system-x86_64 -M q35 -m 2G -bios ovmf-x64/OVMF.fd -hda barebones.hdd
+run-hdd-uefi: ovmf-$(EFI_ARCH) barebones.hdd
+ qemu-system-$(ARCH) -M q35 -m 2G -bios ovmf-$(EFI_ARCH)/OVMF.fd -hda barebones.hdd
-ovmf-x64:
- mkdir -p ovmf-x64
- cd ovmf-x64 && curl -o OVMF-X64.zip https://efi.akeo.ie/OVMF/OVMF-X64.zip && 7z x OVMF-X64.zip
+ovmf-$(EFI_ARCH):
+ mkdir -p ovmf-$(EFI_ARCH)
+ cd ovmf-$(EFI_ARCH) && curl -o OVMF-$(EFI_ARCH).zip https://efi.akeo.ie/OVMF/OVMF-$(EFI_ARCH).zip && 7z x OVMF-$(EFI_ARCH).zip
limine:
git clone https://github.com/limine-bootloader/limine.git --branch=v3.0-branch-binary --depth=1
@@ -58,7 +67,7 @@ barebones.hdd: limine kernel
sudo mount `cat loopback_dev`p1 img_mount
sudo mkdir -p img_mount/EFI/BOOT
sudo cp -v kernel/kernel.elf limine.cfg limine/limine.sys img_mount/
- sudo cp -v limine/BOOTX64.EFI img_mount/EFI/BOOT/
+ sudo cp -v limine/BOOT$(EFI_ARCH).EFI img_mount/EFI/BOOT/
sync
sudo umount img_mount
sudo losetup -d `cat loopback_dev`
@@ -71,5 +80,5 @@ clean:
.PHONY: distclean
distclean: clean
- rm -rf limine ovmf-x64
+ rm -rf limine ovmf-$(EFI_ARCH)
$(MAKE) -C kernel distclean
diff --git a/README.md b/README.md
index 44ca95a..0d41e6b 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,8 @@
# Limine Bare Bones
-This repository will show you how to set up a simple 64-bit x86_64 Long Mode higher half kernel using Limine.
+This repository will show you how to set up a simple 64-bit higher half kernel using Limine.
-This project can be built using the host compiler on most Linux distros on x86_64, but it's recommended you set up an x86_64-elf [cross compiler](https://wiki.osdev.org/GCC_Cross-Compiler).
+This project can be built using the host compiler on most Linux distros, but it's recommended you set up a [cross compiler](https://wiki.osdev.org/GCC_Cross-Compiler) for your target architecture.
It is also recommended to cross reference the contents of this repository with [the Limine Bare Bones](https://wiki.osdev.org/Limine_Bare_Bones) OSDev wiki page.
diff --git a/kernel/GNUmakefile b/kernel/GNUmakefile
index 638f98a..0490512 100644
--- a/kernel/GNUmakefile
+++ b/kernel/GNUmakefile
@@ -1,13 +1,16 @@
+# Target processor architecture.
+ARCH ?= x86_64
+
# This is the name that our final kernel executable will have.
# Change as needed.
override KERNEL := kernel.elf
# Convenience macro to reliably declare overridable command variables.
define DEFAULT_VAR =
- ifeq ($(origin $1), default)
+ ifeq ($(origin $1),default)
override $(1) := $(2)
endif
- ifeq ($(origin $1), undefined)
+ ifeq ($(origin $1),undefined)
override $(1) := $(2)
endif
endef
@@ -32,14 +35,6 @@ override INTERNALCFLAGS := \
-fno-stack-check \
-fno-pie \
-fno-pic \
- -mabi=sysv \
- -mno-80387 \
- -mno-mmx \
- -mno-3dnow \
- -mno-sse \
- -mno-sse2 \
- -mno-red-zone \
- -mcmodel=kernel \
-MMD
# Internal linker flags that should not be changed by the user.
@@ -49,6 +44,25 @@ override INTERNALLDFLAGS := \
-Wl,-z,max-page-size=0x1000 \
-Wl,-T,linker.ld
+# Set archtecture specific variables (and check that the architecture is supported).
+ifeq ($(ARCH),x86_64)
+ override INTERNALCFLAGS += \
+ -m64 \
+ -march=x86-64 \
+ -mabi=sysv \
+ -mno-80387 \
+ -mno-mmx \
+ -mno-sse \
+ -mno-sse2 \
+ -mno-red-zone \
+ -mcmodel=kernel
+ override INTERNALLDFLAGS += \
+ -Wl,-m,elf_x86_64 \
+ -Wl,--oformat=elf64-x86-64
+else
+ $(error Architecture $(ARCH) not supported)
+endif
+
# Use find to glob all *.c files in the directory and extract the object names.
override CFILES := $(shell find ./ -type f -name '*.c')
override OBJ := $(CFILES:.c=.o)
diff --git a/kernel/linker.ld b/kernel/linker.ld
index 8056875..39848ea 100644
--- a/kernel/linker.ld
+++ b/kernel/linker.ld
@@ -1,7 +1,3 @@
-/* Tell the linker that we want an x86_64 ELF64 output file */
-OUTPUT_FORMAT(elf64-x86-64)
-OUTPUT_ARCH(i386:x86-64)
-
/* We want the symbol _start to be our entry point */
ENTRY(_start)