os: rework kernel architecture

Rework the code structure and architecture of the kernel by separating
platform-dependent and platform-independent code more cleanly. As of
this patchset, full feature parity has not been achieved. Nonetheless, a
sufficient subset of functionality has been ported to the new
architecture to demonstrate the feasibility of the new structure.

3 files changed, 92 insertions, 28 deletions

diff --git a/cmake/Modules/ElfTransformations.cmake b/cmake/Modules/ElfTransformations.cmake
new file mode 100644
index 0000000..dfc8576
--- /dev/null
+++ b/cmake/Modules/ElfTransformations.cmake
@@ -0,0 +1,36 @@
+include_guard(GLOBAL)
+
+function(target_extract_debug_symbols TARGET)
+    add_custom_command(TARGET "${TARGET}"
+        POST_BUILD
+        COMMAND "${CMAKE_OBJCOPY}"
+        "--only-keep-debug"
+        "$<TARGET_FILE:${TARGET}>"
+        "$<TARGET_FILE_DIR:${TARGET}>/$<TARGET_FILE_BASE_NAME:${TARGET}>.sym"
+        BYPRODUCTS "${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/$<CONFIGURATION>/${TARGET}.sym"
+        COMMENT "Extracting debug symbols from $<TARGET_FILE:${TARGET}> ..."
+    )
+endfunction()
+
+function(target_strip TARGET)
+    add_custom_command(TARGET "${TARGET}"
+        POST_BUILD
+        COMMAND "${CMAKE_STRIP}"
+        "$<TARGET_FILE:${TARGET}>"
+        COMMENT "Stripping $<TARGET_FILE:${TARGET}> ..."
+    )
+endfunction()
+
+function(target_disassemble TARGET)
+    add_custom_command(TARGET "${TARGET}"
+        POST_BUILD
+        COMMAND "${CMAKE_OBJDUMP}"
+        "--disassemble"
+        "--visualize-jumps"
+        "--demangle"
+        "$<TARGET_FILE:${TARGET}>"
+        ">$<TARGET_FILE_DIR:${TARGET}>/$<TARGET_FILE_BASE_NAME:${TARGET}>.dis"
+        BYPRODUCTS "${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/$<CONFIGURATION>/${TARGET}.dis"
+        COMMENT "Dumping disassembly for $<TARGET_FILE:${TARGET}> ..."
+    )
+endfunction()
diff --git a/cmake/Modules/GenerateBootableIso.cmake b/cmake/Modules/GenerateBootableIso.cmake
new file mode 100644
index 0000000..3d1ee30
--- /dev/null
+++ b/cmake/Modules/GenerateBootableIso.cmake
@@ -0,0 +1,22 @@
+include_guard(GLOBAL)
+
+function(target_generate_bootable_iso TARGET)
+    find_package("grub-mkrescue")
+
+    file(GENERATE
+        OUTPUT "$<TARGET_FILE_DIR:${TARGET}>/isofs/boot/grub/grub.cfg"
+        INPUT "${PROJECT_SOURCE_DIR}/arch/${CMAKE_SYSTEM_PROCESSOR}/support/grub.cfg.in"
+    )
+
+    add_custom_command(TARGET "${TARGET}"
+        POST_BUILD
+        COMMAND "${GRUB_MKRESCUE_EXE}"
+        "-o"
+        "$<TARGET_FILE_DIR:${TARGET}>/${TARGET}.iso"
+        "$<TARGET_FILE_DIR:${TARGET}>/isofs"
+        "$<TARGET_FILE:${TARGET}>"
+        "2>/dev/null"
+        BYPRODUCTS "${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/$<CONFIGURATION>/${TARGET}.iso"
+        COMMENT "Creating bootable ISO image"
+    )
+endfunction()
diff --git a/cmake/Platforms/x86_64.cmake b/cmake/Platforms/x86_64.cmake
index e0518b5..b17fec8 100644
--- a/cmake/Platforms/x86_64.cmake
+++ b/cmake/Platforms/x86_64.cmake
@@ -1,35 +1,41 @@
-execute_process(COMMAND "x86_64-pc-elf-g++" "-mno-red-zone" "-print-file-name=crtbegin.o"
-  OUTPUT_VARIABLE CRT_BEGIN
-  ERROR_QUIET
-)
-string(STRIP "${CRT_BEGIN}" CRT_BEGIN)
-mark_as_advanced(CRT_BEGIN)
-
-string(REGEX REPLACE "/crtbegin.o" "" CMAKE_SYSROOT "${CRT_BEGIN}")
-mark_as_advanced(CMAKE_SYSROOT)
+include_guard(GLOBAL)
 
-set(SYSTEM_NAME "Generic")
+set(PLATFORM_TARGET "x86_64-pc-elf")
 
 set(CMAKE_TRY_COMPILE_TARGET_TYPE "STATIC_LIBRARY")
 
-set(CMAKE_C_COMPILER "x86_64-pc-elf-gcc")
-set(CMAKE_CXX_COMPILER "x86_64-pc-elf-g++")
+set(CMAKE_SYSTEM_NAME "Generic-ELF")
+set(CMAKE_SYSTEM_PROCESSOR "x86_64")
+
+set(CMAKE_ASM_COMPILER_TARGET "${PLATFORM_TARGET}")
+set(CMAKE_CXX_COMPILER_TARGET "${PLATFORM_TARGET}")
+
+find_program(CMAKE_ASM_COMPILER "${CMAKE_ASM_COMPILER_TARGET}-g++" REQUIRED)
+find_program(CMAKE_CXX_COMPILER "${CMAKE_CXX_COMPILER_TARGET}-g++" REQUIRED)
+
+set(CMAKE_CXX_FLAGS_INIT
+    "-mno-red-zone"
+    "-mcmodel=kernel"
+    "-fno-pie"
+    "-fno-rtti"
+    "-fno-exceptions"
+    "-fno-use-cxa-atexit"
+    "-ffunction-sections"
+    "-fdata-sections"
+)
+
+list(JOIN CMAKE_CXX_FLAGS_INIT " " CMAKE_CXX_FLAGS_INIT)
+
+set(CMAKE_EXE_LINKER_FLAGS_INIT "-Wl,--gc-sections")
 
-set(CMAKE_CXX_FLAGS_INIT "-m64 -mno-red-zone -mcmodel=large -fno-rtti -fno-exceptions -ffunction-sections -fdata-sections")
 set(CMAKE_CXX_FLAGS_DEBUG "-ggdb3")
 set(CMAKE_ASM_FLAGS_DEBUG "-ggdb3")
-set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-ggdb3")
-set(CMAKE_ASM_FLAGS_RELWITHDEBINFO "-ggdb3")
-set(CMAKE_EXE_LINKER_FLAGS_INIT "-nostartfiles -Wl,--gc-sections")
-set(CMAKE_CXX_LINK_EXECUTABLE
-  "<CMAKE_CXX_COMPILER> \
-  <FLAGS> \
-  <CMAKE_CXX_LINK_FLAGS> \
-  <LINK_FLAGS> \
-  ${CMAKE_SYSROOT}/crtbegin.o \
-  <OBJECTS> \
-  -o <TARGET> \
-  <LINK_LIBRARIES> \
-  -lgcc \
-  ${CMAKE_SYSROOT}/crtend.o"
-)
+
+set(CMAKE_ASM_FLAGS_MINSIZEREL "-Os -DNDEBUG -ggdb3")
+set(CMAKE_CXX_FLAGS_MINSIZEREL "-Os -DNDEBUG -ggdb3")
+
+set(CMAKE_ASM_FLAGS_RELEASE "-O3 -DNDEBUG -ggdb3")
+set(CMAKE_CXX_FLAGS_RELEASE "-O3 -DNDEBUG -ggdb3")
+
+set(CMAKE_ASM_FLAGS_RELWITHDEBINFO "-O2 -DNDEBUG -ggdb3")
+set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -DNDEBUG -ggdb3")