Barebones Kernel Commit

Uses limine to boot off of a disk.
Outputs a character to the debug port.

zion/CMakeLists.txt

@@ -0,0 +1,36 @@
+add_executable(zion
+  zion.cpp)
+
+# -c -- Don't run the linker.
+# -nostdlib -- Don't include the standard library.
+# -mabi=sysv -- Explicitly specify the ABI since we will rely on it.
+# -mno-red-zone -- Don't put data below the stack pointer (clobbered by interrupts).
+# -mcmodel=kernel -- Assume the kernel code is running in the higher half.
+# -mgeneral-regs-only -- Prevent GCC from using a whole host of nonsense registers (that we have to enable).
+# Hopefully preceded by -mgeneral-regs-only
+# -mno-80387
+# -mno-mmx
+# -mno-3dnow
+# -mno-sse -mno-sse2
+# -MMD -- Something with the preprocessor?
+set(_Z_COMPILE_FLAGS "${CMAKE_CXX_FLAGS} -ffreestanding -nostdlib -mabi=sysv -mno-red-zone -mcmodel=kernel -mgeneral-regs-only")
+# -mno-80387 -mno-mmx -mno-3dnow -mno-sse -mno-sse2 -MMD
+
+set(_Z_LINK_SCRIPT "${CMAKE_CURRENT_SOURCE_DIR}/linker.ld")
+
+# -lgcc -- Link against gcc internals. Not sure if necessary.
+# -nostdlib -- Don't try to link against the stdlib.
+# -nostartfiles -- Don't try to link against crt0.s
+# -static -- Prevent trying something with shared libraries (probably irrelevant).
+# -z max-page-size=0x1000 -- Assume 4 KiB Pages.
+set(_Z_LINK_FLAGS "-T ${_Z_LINK_SCRIPT} -lgcc -nostdlib -nostartfiles -static -z max-page-size=0x1000")
+
+
+# Don't try to dynamically link.
+set(CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS "")
+
+set_target_properties(zion
+  PROPERTIES
+  COMPILE_FLAGS "${_Z_COMPILE_FLAGS}"
+  LINK_FLAGS "${_Z_LINK_FLAGS}"
+  )