Initial commit

1 files changed, 233 insertions, 0 deletions

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..63d388a
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,233 @@
+MAKEFLAGS += --no-builtin-rules
+MAKEFLAGS += --no-builtin-variables
+
+# The project version.
+VERSION = 0.1
+
+# The selected C compiler.
+#
+# Here is an example of overriding the compiler :
+# $ make CC=clang
+CC = gcc
+
+# C preprocessor flags.
+#
+# Use man gcc for more details. On Debian, the GNU FDL license is considered
+# non free, and as a result, the gcc-doc package is part of the non-free
+# components.
+
+# Generate code for a 32-bits environment.
+X1_CPPFLAGS = -m32
+
+# Do not search the standard system directories for header files.
+# The kernel is a free standing environment, where no host library can
+# work, at least not without (usually heavy) integration work.
+X1_CPPFLAGS += -nostdinc
+
+# The -I option is used to add directories to the search list.
+X1_CPPFLAGS += -Iinclude -I.
+
+# The -print-file-name=include option prints the directory where the compiler
+# headers are located. This directory is normally part of the standard system
+# directories for header files, excluded by the -nostdinc option. But the
+# C free standing environment still assumes the availability of some headers
+# which can be found there.
+X1_CPPFLAGS += -isystem $(shell $(CC) -print-file-name=include)
+
+# Pass the project version as a macro.
+X1_CPPFLAGS += -DVERSION="$(VERSION)"
+
+# Append user-provided preprocessor flags, if any.
+#
+# Here is an example that turns off assertions :
+# $ make CPPFLAGS=-DNDEBUG
+X1_CPPFLAGS += $(CPPFLAGS)
+
+# C flags.
+#
+# Use man gcc for more details. On Debian, the GNU FDL license is considered
+# non free, and as a result, the gcc-doc package is part of the non-free
+# components.
+
+# These are common warning options.
+X1_CFLAGS = -Wall -Wextra -Wmissing-prototypes -Wstrict-prototypes
+
+# Enable warnings about shadow declarations. A shadow declaration occurs
+# when a name, e.g. a variable name, "hides" another declaration with the
+# same name, but from an outer scope. Here is an example :
+#
+# int
+# main(void)
+# {
+#     int a;
+#
+#     {
+#         int a;
+#     }
+# }
+#
+# Local variables may shadow global variables, which is why global
+# names are usually prefixed with a namespace name. Another common
+# case is variables declared inside function-like macros, where a
+# popular solution is to prefix the names with a number of underscores.
+X1_CFLAGS += -Wshadow
+
+# This is currently a Clang-specific warning about declarations that are
+# unused, a problem that quickly occurs when using conditional compilation
+# like assertions.
+X1_CFLAGS += -Wno-unneeded-internal-declaration
+
+# Set the language as C99 with GNU extensions.
+X1_CFLAGS += -std=gnu99
+
+# Build with optimizations as specified by the -O2 option.
+X1_CFLAGS += -O2
+
+# Include debugging symbols, giving inspection tools a lot more debugging
+# data to work with, e.g. allowing them to translate between addresses and
+# source locations.
+X1_CFLAGS += -g
+
+# Target a free standing environment as defined by C99.
+#
+# This option tells the compiler that it may not assume a hosted environment,
+# e.g. that it cannot assume the availability of the C library.
+#
+# See ISO/IEC 9899:1999 5.1.2.1 "Freestanding environment" for all the details.
+X1_CFLAGS += -ffreestanding
+
+# Keep using the frame pointer.
+#
+# When a function is called, the stack pointer (esp) points to the "end" of
+# the stack frame, and the frame or base pointer (ebp) points to the
+# "beginning". When optimizations are enabled, the compiler only uses the
+# stack pointer as a base pointer to refer to temporary data saved on the
+# stack frame, and therefore omits the base pointer to gain a register.
+# But this prevents debuggers from easily unwinding the stack since the
+# base pointer allowed conveniently retrieving the return address. This
+# option tells the compiler to keep the base pointer so that GDB can
+# produce valid backtraces.
+X1_CFLAGS += -fno-omit-frame-pointer
+
+# Disable the generation of extra code for stack protection, as it requires
+# additional support in the kernel which is beyond its scope, and may be
+# enabled by default on some distributions.
+X1_CFLAGS += -fno-stack-protector
+
+# Disable strict aliasing, a C99 rule that states that pointers of different
+# types may never refer to the same memory. Strict aliasing may provide
+# performance improvements for some rare cases but may also cause weird bugs
+# when casting pointers.
+X1_CFLAGS += -fno-strict-aliasing
+
+# Force all uninitialized global variables into a data section instead of
+# generating them as "common blocks". If multiple definitions of the same
+# global variable are made, this option will make the link fail.
+X1_CFLAGS += -fno-common
+
+# Disable all extended intruction sets that require special kernel support.
+X1_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
+
+# Append user-provided compiler flags, if any.
+#
+# Here are some examples :
+# $ make CFLAGS="-O0 -g3"
+#   Disable optimizations and include extra debugging information
+# $ make CPPFLAGS=-DNDEBUG CFLAGS="-Os -flto -g0"
+#   Disable assertions, optimize for size, enable LTO (link-time optimizations),
+#   and don't produce debugging information
+#
+# Because these flags are added last, they can override any flag set in this
+# Makefile.
+X1_CFLAGS += $(CFLAGS)
+
+# Linker flags.
+#
+# These are also GCC options, so use man gcc for more details. On Debian,
+# the GNU FDL license is considered non free, and as a result, the gcc-doc
+# package is part of the non-free components.
+
+# Link for a 32-bits environment.
+X1_LDFLAGS = -m32
+
+# Build a static executable, with no shared library.
+X1_LDFLAGS += -static
+
+# Do not use the standard system startup files or libraries when linking.
+# The kernel is a free standing environment, where no host library can
+# work, at least not without (usually heavy) integration work.
+X1_LDFLAGS += -nostdlib
+
+# Disable the generation of a build ID, a feature usually enabled by default
+# on many distributions. A build ID is linked in its own special section, so
+# disabling it makes the linker script simpler.
+X1_LDFLAGS += -Xlinker --build-id=none
+
+# Pass the linker script path to the linker.
+X1_LDFLAGS += -Xlinker -T src/kernel.lds
+
+# Append user-provided linker flags, if any.
+X1_LDFLAGS += $(LDFLAGS)
+
+# Link against libgcc. This library is a companion to the compiler and
+# adds support for operations required by C99 but that the hardware
+# doesn't provide. An example is 64-bits integer additions on a 32-bits
+# processor or a 64-bits processor running in 32-bits protected mode.
+LIBS = -lgcc
+
+BINARY = x1
+
+SOURCES = \
+	src/boot_asm.S \
+	src/boot.c \
+	src/condvar.c \
+	src/cpu.c \
+	src/cpu_asm.S \
+	src/error.c \
+	src/i8254.c \
+	src/i8259.c \
+	src/io_asm.S \
+	src/main.c \
+	src/mem.c \
+	src/mutex.c \
+	src/panic.c \
+	src/stdio.c \
+	src/string.c \
+	src/sw.c \
+	src/thread_asm.S \
+	src/thread.c \
+	src/timer.c \
+	src/uart.c
+
+SOURCES += \
+	lib/cbuf.c \
+	lib/fmt.c \
+	lib/shell.c
+
+OBJECTS = $(patsubst %.S,%.o,$(patsubst %.c,%.o,$(SOURCES)))
+
+$(BINARY): $(OBJECTS)
+	$(CC) -o $@ $(X1_LDFLAGS) $^ $(LIBS)
+
+%.o: %.c
+	$(CC) $(X1_CPPFLAGS) $(X1_CFLAGS) -c -o $@ $<
+
+%.o: %.S
+	$(CC) $(X1_CPPFLAGS) $(X1_CFLAGS) -c -o $@ $<
+
+clean:
+	rm -f $(BINARY) $(OBJECTS)
+
+# Making all sources phony means that make will always consider them and
+# the targets using them as dependencies as obsolete. This basically forces
+# make to rebuild all files, all the time. It's obviously not the best
+# way to compile, but it's simple and reliable.
+#
+# The modern approach is to make compilation incremental, by generating
+# dependency Makefiles with the compiler, which are then included in the
+# main Makefile so that a target may only be rebuilt if any of its
+# dependencies is newer. Check the X15 project [1] for an example of this
+# technique.
+#
+# [1] https://git.sceen.net/rbraun/x15.git/
+.PHONY: clean $(SOURCES)