From 9477ad40fc30ccb185debc4ca0bb1dffba7ea6ca Mon Sep 17 00:00:00 2001
From: mintsuki <mintsuki@protonmail.com>
Date: Wed, 29 Mar 2023 00:04:07 +0200
Subject: [PATCH] zealbooter: Rebase on latest limine-barebones code

---
 .gitignore             | 10 ++---
 zealbooter/GNUmakefile | 85 +++++++++++++++++++++++-------------------
 zealbooter/linker.ld   |  4 ++
 3 files changed, 56 insertions(+), 43 deletions(-)

diff --git a/.gitignore b/.gitignore
index de756d76..127eb5d8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,17 +2,17 @@
 *.bin
 *.ZXE
 *.MAP
-src/Boot/
+/src/Boot
 *.ELF
 *.elf
 *.sys
 *.SYS
-src/EFI/
-build/limine
-build/ovmf
+/src/EFI
+/build/limine
+/build/ovmf
 *.iso
 *.raw
 *.hdd
 *.o
 *.d
-zealbooter/limine.h
+/zealbooter/limine.h
diff --git a/zealbooter/GNUmakefile b/zealbooter/GNUmakefile
index ff39eaf3..d8f30e28 100644
--- a/zealbooter/GNUmakefile
+++ b/zealbooter/GNUmakefile
@@ -1,8 +1,11 @@
+# Nuke built-in rules and variables.
+override MAKEFLAGS += -rR
+
 # This is the name that our final kernel executable will have.
 # Change as needed.
 override KERNEL := zealbooter.elf
 
-# Convenience macro to reliably declare overridable command variables.
+# Convenience macro to reliably declare user overridable variables.
 define DEFAULT_VAR =
     ifeq ($(origin $1),default)
         override $(1) := $(2)
@@ -20,49 +23,54 @@ $(eval $(call DEFAULT_VAR,CC,cc))
 # Same thing for "ld" (the linker).
 $(eval $(call DEFAULT_VAR,LD,ld))
 
-# User controllable CFLAGS.
-CFLAGS ?= -g -O2 -pipe -Wall -Wextra
+# User controllable C flags.
+$(eval $(call DEFAULT_VAR,CFLAGS,-g -O2 -pipe -Wall -Wextra))
 
-# User controllable preprocessor flags. We set none by default.
-CPPFLAGS ?=
+# User controllable C preprocessor flags. We set none by default.
+$(eval $(call DEFAULT_VAR,CPPFLAGS,))
 
 # User controllable nasm flags.
-NASMFLAGS ?= -F dwarf -g
+$(eval $(call DEFAULT_VAR,NASMFLAGS,-F dwarf -g))
 
 # User controllable linker flags. We set none by default.
-LDFLAGS ?=
+$(eval $(call DEFAULT_VAR,LDFLAGS,))
 
 # Internal C flags that should not be changed by the user.
-override CFLAGS +=       \
-    -std=gnu11           \
-    -ffreestanding       \
+override CFLAGS += \
+    -std=gnu11 \
+    -ffreestanding \
     -fno-stack-protector \
-    -fno-stack-check     \
-    -fno-lto             \
-    -fno-pie             \
-    -fno-pic             \
-    -m64                 \
-    -march=x86-64        \
-    -mabi=sysv           \
-    -mno-80387           \
-    -mno-mmx             \
-    -mno-sse             \
-    -mno-sse2            \
-    -mno-red-zone        \
-    -mcmodel=kernel      \
-    -MMD                 \
-    -I.                  \
-    -I./lib
+    -fno-stack-check \
+    -fno-lto \
+    -fno-pie \
+    -fno-pic \
+    -m64 \
+    -march=x86-64 \
+    -mabi=sysv \
+    -mno-80387 \
+    -mno-mmx \
+    -mno-sse \
+    -mno-sse2 \
+    -mno-red-zone \
+    -mcmodel=kernel
+
+# Internal C preprocessor flags that should not be changed by the user.
+override CPPFLAGS := \
+    -I. \
+    -I./lib \
+    $(CPPFLAGS) \
+    -MMD \
+    -MP
 
 # Internal linker flags that should not be changed by the user.
-override LDFLAGS +=         \
-    -nostdlib               \
-    -static                 \
-    -m elf_x86_64           \
+override LDFLAGS += \
+    -nostdlib \
+    -static \
+    -m elf_x86_64 \
     -z max-page-size=0x1000 \
     -T linker.ld
 
-# Check if the linker supports -no-pie and enable it if it does
+# Check if the linker supports -no-pie and enable it if it does.
 ifeq ($(shell $(LD) --help 2>&1 | grep 'no-pie' >/dev/null 2>&1; echo $$?),0)
     override LDFLAGS += -no-pie
 endif
@@ -71,10 +79,11 @@ endif
 override NASMFLAGS += \
     -f elf64
 
-# Use find to glob all *.c, *.S, and *.asm files in the directory and extract the object names.
-override CFILES := $(shell find . -type f -name '*.c')
-override ASFILES := $(shell find . -type f -name '*.S')
-override NASMFILES := $(shell find . -type f -name '*.asm')
+# Use "find" to glob all *.c, *.S, and *.asm files in the tree and obtain the
+# object and header dependency file names.
+override CFILES := $(shell find -L . -type f -name '*.c')
+override ASFILES := $(shell find -L . -type f -name '*.S')
+override NASMFILES := $(shell find -L . -type f -name '*.asm')
 override OBJ := $(CFILES:.c=.o) $(ASFILES:.S=.o) $(NASMFILES:.asm=.o)
 override HEADER_DEPS := $(CFILES:.c=.d) $(ASFILES:.S=.d)
 
@@ -83,7 +92,7 @@ override HEADER_DEPS := $(CFILES:.c=.d) $(ASFILES:.S=.d)
 all: $(KERNEL)
 
 limine.h:
-	curl https://raw.githubusercontent.com/limine-bootloader/limine/trunk/limine.h -o $@ || cp ../build/limine/limine.h limine.h || echo "ERROR"
+	curl -Lo $@ https://github.com/limine-bootloader/limine/raw/trunk/limine.h || cp ../build/limine/limine.h limine.h || echo "ERROR"
 
 # Link rules for the final kernel executable.
 $(KERNEL): $(OBJ)
@@ -94,11 +103,11 @@ $(KERNEL): $(OBJ)
 
 # Compilation rules for *.c files.
 %.o: %.c limine.h
-	$(CC) $(CPPFLAGS) $(CFLAGS) -c $< -o $@
+	$(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $@
 
 # Compilation rules for *.S files.
 %.o: %.S limine.h
-	$(CC) $(CPPFLAGS) $(CFLAGS) -c $< -o $@
+	$(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $@
 
 # Compilation rules for *.asm (nasm) files.
 %.o: %.asm
diff --git a/zealbooter/linker.ld b/zealbooter/linker.ld
index 36452585..529a4dd1 100644
--- a/zealbooter/linker.ld
+++ b/zealbooter/linker.ld
@@ -40,6 +40,10 @@ SECTIONS
         *(.data .data.*)
     } :data
 
+    /* NOTE: .bss needs to be the last thing mapped to :data, otherwise lots of */
+    /* unnecessary zeros will be written to the binary. */
+    /* If you need, for example, .init_array and .fini_array, those should be placed */
+    /* above this. */
     .bss : {
         *(COMMON)
         *(.bss .bss.*)