Give kernel image a header.

Kernel image now has a header with version, magic number, and a
pointer to its actual entrypoint. Entry point is now _start in
boot.s, and we now generate versions.s in the build tree for the
version macros.

Makefile

@@ -5,6 +5,7 @@ include src/arch/$(ARCH)/config.mk
 BUILD_D        := build
 ARCH_D         := src/arch/$(ARCH)
 VERSION        ?= $(shell git describe --dirty --always)
+GITSHA         ?= $(shell git rev-parse --short HEAD)
 
 KERNEL_FILENAME:= popcorn.bin
 
@@ -48,7 +49,8 @@ WARNFLAGS      += -Wno-format-extra-args -Wno-unused-result
 WARNFLAGS      += -Wno-deprecated-declarations -Wno-unused-function
 WARNFLAGS      += -Wno-unused-but-set-parameter
 
-ASFLAGS        ?= 
+ASFLAGS        ?=
+ASFLAGS        += -p $(BUILD_D)/versions.s
 
 CFLAGS         := $(INCLUDES) $(DEPENDFLAGS) $(BASEFLAGS) $(WARNFLAGS)
 CFLAGS         += -std=c11 -fshort-wchar
@@ -64,14 +66,13 @@ ifdef MAX_HRES
 BOOT_CFLAGS    += -DMAX_HRES=$(MAX_HRES)
 endif
 
-LDFLAGS        := -L $(BUILD_D) -ggdb -shared
+LDFLAGS        := -L $(BUILD_D) -ggdb
 LDFLAGS        += -nostdlib -znocombreloc -Bsymbolic -nostartfiles 
 
-BOOT_LDFLAGS   := $(LDFLAGS)
+BOOT_LDFLAGS   := $(LDFLAGS) -shared
-BOOT_LDFLAGS   += -fPIC
 BOOT_LDFLAGS   += -L $(EFI_ARCH_DIR)/lib -L $(EFI_ARCH_DIR)/gnuefi
 
-AS             ?= $(CROSS)as
+AS             ?= $(CROSS)nasm
 AR             ?= $(CROSS)ar
 CC             ?= $(CROSS)gcc
 CXX            ?= $(CROSS)g++
@@ -120,11 +121,17 @@ clean:
 dist-clean: clean
 	make -C external/gnu-efi clean
 
-.PHONY: all clean dist-clean init
+dump: $(BUILD_D)/kernel.dump
+	vim $<
+
+.PHONY: all clean dist-clean init dump
 
 $(BUILD_D)/.version:
 	echo '$(VERSION)' | cmp -s - $@ || echo '$(VERSION)' > $@
 
+$(BUILD_D)/versions.s:
+	./parse_version.py "$(VERSION)" "$(GITSHA)" > $@
+
 -include x $(patsubst %,src/modules/%/module.mk,$(MODULES))
 -include x $(DEPS)
 
@@ -153,21 +160,20 @@ $(BUILD_D)/%.bin: $(BUILD_D)/%.elf
 $(BUILD_D)/boot.dump: $(BUILD_D)/boot.efi
 	$(OBJD) -D -S $< > $@
 
-$(BUILD_D)/boot/%.s.o: src/boot/%.s $(INIT_DEP)
+$(BUILD_D)/boot/%.s.o: src/boot/%.s $(BUILD_D)/versions.s $(INIT_DEP)
 	$(AS) $(ASFLAGS) -o $@ $<
 
 $(BUILD_D)/boot/%.c.o: src/boot/%.c $(INIT_DEP)
 	$(CC) $(BOOT_CFLAGS) -c -o $@ $<
 
 $(BUILD_D)/kernel.elf: $(KOBJS) $(MOD_TARGETS) $(ARCH_D)/kernel.ld
-	$(LD) $(LDFLAGS) -u kernel_main -T $(ARCH_D)/kernel.ld -o $@ $(KOBJS) $(patsubst %,-l%,$(MODULES))
+	$(LD) $(LDFLAGS) -u _header -T $(ARCH_D)/kernel.ld -o $@ $(patsubst %,-l%,$(MODULES)) $(KOBJS)
 	$(OBJC) --only-keep-debug $@ $@.sym
-	$(OBJC) --strip-debug $@
 
 $(BUILD_D)/kernel.dump: $(BUILD_D)/kernel.elf
 	$(OBJD) -D -S $< > $@
 
-$(BUILD_D)/arch/%.s.o: $(ARCH_D)/%.s $(INIT_DEP)
+$(BUILD_D)/arch/%.s.o: $(ARCH_D)/%.s $(BUILD_D)/versions.s $(INIT_DEP)
 	$(AS) $(ASFLAGS) -o $@ $<
 
 $(BUILD_D)/arch/%.c.o: $(ARCH_D)/%.c $(INIT_DEP)

modules.mk

@@ -16,13 +16,16 @@ MOD_BUILD_D	:= $(BUILD_D)/d.$(MOD_NAME)
 MOD_LIBNAME	:= $(BUILD_D)/lib$(MOD_NAME).a
 MOD_TARGETS	+= $(MOD_LIBNAME)
 
-OBJS_$(MOD_NAME) := $(patsubst %.c,build/d.%.o,$(patsubst src/modules/%,%,$(SOURCES)))
+OBJS_$(MOD_NAME) := $(patsubst %,build/d.%.o,$(patsubst src/modules/%,%,$(SOURCES)))
 
 $(MOD_LIBNAME): $(OBJS_$(MOD_NAME))
 	$(AR) cr $@ $(OBJS_$(MOD_NAME))
 
-$(MOD_BUILD_D)/%.o: $(MOD_SRC_D)/%.c $(INIT_DEP)
+$(MOD_BUILD_D)/%.c.o: $(MOD_SRC_D)/%.c $(INIT_DEP)
 	$(CC) $(CFLAGS) -c -o $@ $<
 
+$(MOD_BUILD_D)/%.s.o: $(MOD_SRC_D)/%.s $(BUILD_D)/versions.s $(INIT_DEP)
+	$(AS) $(ASFLAGS) -o $@ $<
+
 DEPS += $(patsubst %.o,%.d,$(OBJS_$(MOD_NAME)))
 

parse_version.py

@@ -0,0 +1,36 @@
+#!/usr/bin/env python3
+#
+# parse_version.py - Create a NASM version definition file given
+# version inputs. Usage:
+#
+#     parse_version.py <git-describe version> <git short sha>
+
+
+def split_version(version_string):
+    major, minor, patch_dirty = version_string.split(".")
+    patch_dirty = patch_dirty.split("-")
+
+    return major, minor, patch_dirty[0], len(patch_dirty) > 1
+
+
+def make_nasm(major, minor, patch, dirty, sha):
+    if dirty:
+        dirty = "1"
+    else:
+        dirty = "0"
+
+    lines = [
+        "%define VERSION_MAJOR  {}".format(major),
+        "%define VERSION_MINOR  {}".format(minor),
+        "%define VERSION_PATCH  {}".format(patch),
+        "%define VERSION_GITSHA 0x{}{}".format(dirty, sha),
+    ]
+    return "\n".join(lines)
+
+
+if __name__ == "__main__":
+    import sys
+    if len(sys.argv) != 3:
+        print("Usage: {} <desc version> <git sha>".format(sys.argv[0]), file=sys.stderr)
+        sys.exit(1)
+    print(make_nasm(*split_version(sys.argv[1]), sys.argv[2]))

src/arch/x86_64/kernel.ld

@@ -1,11 +1,15 @@
-ENTRY(kernel_main)
+ENTRY(_start)
 SECTIONS
 {
 	. = 0x100000;
 
+	.header : {
+		header = .;
+		KEEP(*(.header))
+	}
+
 	.text : {
 		code = .;
-		*(.text.entry)
 		*(.text)
 	}
 
@@ -24,5 +28,5 @@ SECTIONS
 		*(.note.*)
 	}
 
-	end = ALIGN(4096);
+	kernel_end = ALIGN(4096);
 }

src/boot/console.c

@@ -62,16 +62,16 @@ con_initialize (const CHAR16 *version)
 	CHECK_EFI_STATUS_OR_RETURN(status, "ClearScreen");
 
 	ST->ConOut->SetAttribute(ST->ConOut, EFI_LIGHTCYAN);
-	ST->ConOut->OutputString(ST->ConOut, (CHAR16*)L"Popcorn OS ");
+	ST->ConOut->OutputString(ST->ConOut, (CHAR16*)L"Popcorn loader ");
 
 	ST->ConOut->SetAttribute(ST->ConOut, EFI_LIGHTMAGENTA);
 	ST->ConOut->OutputString(ST->ConOut, (CHAR16*)version);
 
 	ST->ConOut->SetAttribute(ST->ConOut, EFI_LIGHTGRAY);
-	ST->ConOut->OutputString(ST->ConOut, (CHAR16*)L" booting...\r\n");
+	ST->ConOut->OutputString(ST->ConOut, (CHAR16*)L" booting...\r\n\n");
 
 	con_status_begin(L"Setting console display mode: ");
-	Print(L"%ux%u (%ux%u chars)",
+	Print(L"\n    %ux%u (%ux%u chars)",
 		gfx_out_proto->Mode->Info->HorizontalResolution,
 		gfx_out_proto->Mode->Info->VerticalResolution,
 		ROWS, COLS);
@@ -91,14 +91,14 @@ void
 con_status_ok ()
 {
 	UINTN row = ST->ConOut->Mode->CursorRow;
-	ST->ConOut->SetCursorPosition(ST->ConOut, COLS-8, row);
+	ST->ConOut->SetCursorPosition(ST->ConOut, 4, ++row);
 	ST->ConOut->SetAttribute(ST->ConOut, EFI_LIGHTGRAY);
 	ST->ConOut->OutputString(ST->ConOut, (CHAR16*)L"[");
 	ST->ConOut->SetAttribute(ST->ConOut, EFI_GREEN);
 	ST->ConOut->OutputString(ST->ConOut, (CHAR16*)L"  ok  ");
 	ST->ConOut->SetAttribute(ST->ConOut, EFI_LIGHTGRAY);
 	ST->ConOut->OutputString(ST->ConOut, (CHAR16*)L"]\r");
-	ST->ConOut->SetCursorPosition(ST->ConOut, 0, row+1);
+	ST->ConOut->SetCursorPosition(ST->ConOut, 0, ++row+1);
 }
 
 void

src/boot/main.c

@@ -10,6 +10,19 @@
 	#define GIT_VERSION L"no version"
 #endif
 
+#define KERNEL_MAGIC 0x600db007
+
+#pragma pack(push, 1)
+struct kernel_version {
+	uint32_t magic;
+	uint8_t major;
+	uint8_t minor;
+	uint16_t patch;
+	uint32_t gitsha;
+	void *entrypoint;
+};
+#pragma pack(pop)
+
 EFI_STATUS
 efi_main (EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
 {
@@ -26,19 +39,39 @@ efi_main (EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
 	// because the console is now set up
 
 	// Get info about the image
+	/*
 	con_status_begin(L"Gathering image information...");
 	EFI_LOADED_IMAGE *info = 0;
 	EFI_GUID image_proto = EFI_LOADED_IMAGE_PROTOCOL_GUID;
 	status = ST->BootServices->HandleProtocol(ImageHandle, &image_proto, (void **)&info);
 	CHECK_EFI_STATUS_OR_FAIL(status);
 	con_status_ok();
+	*/
 
 	con_status_begin(L"Loading kernel into memory...");
 	void *kernel_image = NULL;
 	uint64_t kernel_length = 0;
 	status = loader_load_kernel(&kernel_image, &kernel_length);
 	CHECK_EFI_STATUS_OR_FAIL(status);
-	Print(L" %u bytes at 0x%x", kernel_length, kernel_image);
+	Print(L"\n    %u bytes at 0x%x", kernel_length, kernel_image);
+
+	struct kernel_version *version = (struct kernel_version*)kernel_image;
+	if (version->magic != KERNEL_MAGIC) {
+		Print(L"\n    bad magic %x", version->magic);
+		CHECK_EFI_STATUS_OR_FAIL(EFI_CRC_ERROR);
+	}
+
+	Print(L"\n    Kernel version %d.%d.%d %x%s",
+			version->major,
+			version->minor,
+			version->patch,
+			version->gitsha & 0x0fffffff,
+			version->gitsha & 0xf0000000 ? "*" : ""
+		 );
+
+	Print(L"\n    Entrypoint %d", version->entrypoint);
+
+	void (*kernel_main)() = version->entrypoint;
 	con_status_ok();
 
 	//memory_dump_map();
@@ -55,6 +88,9 @@ efi_main (EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
 	status = memory_mark_address_for_update((void**)&kernel_image);
 	CHECK_EFI_STATUS_OR_FAIL(status);
 
+	status = memory_mark_address_for_update((void**)&kernel_main);
+	CHECK_EFI_STATUS_OR_FAIL(status);
+
 	status = memory_get_map(&memory_map,
 			&memmap_size, &memmap_key,
 			&desc_size, &desc_version);
@@ -70,10 +106,7 @@ efi_main (EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
 
 	CHECK_EFI_STATUS_OR_FAIL(status);
 
-	void (*kernel_main)() = kernel_image;
 	kernel_main();
-
+	return EFI_LOAD_ERROR;
-	while (1) __asm__("hlt");
-	return status;
 }
 

src/modules/main/boot.s

@@ -0,0 +1,26 @@
+MAGIC	equ  0x600db007			; Popcorn OS header magic number
+
+section .header
+align 4
+global _header
+_header:
+	dd MAGIC
+	db VERSION_MAJOR
+	db VERSION_MINOR
+	dw VERSION_PATCH
+	dd VERSION_GITSHA
+	dq _start
+
+section .text
+align 16
+global _start:function (_start.end - _start)
+_start:
+	extern kernel_main
+	call kernel_main
+
+	cli
+
+.hang:
+	hlt
+	jmp .hang
+.end:

src/modules/main/debug.s

@@ -0,0 +1,13 @@
+
+section .text
+global do_the_set_registers
+do_the_set_registers:
+	mov rax, 0xdeadbeef0badc0de
+	mov rbx, 0xdeadbeef0badc0de
+	mov rcx, 0xdeadbeef0badc0de
+	mov rdx, 0xdeadbeef0badc0de
+
+global _halt
+_halt:
+	hlt
+	jmp _halt

src/modules/main/main.c

@@ -1,8 +1,13 @@
-__attribute__((section(".text.entry")))
+#include "vga.h"
+
+void do_the_set_registers();
+
 void kernel_main() {
 	volatile register int foo = 0x1a1b1c10;
 	volatile register int bar = 0;
 
-	while(1)
+	terminal_initialize(5);
-		foo = foo | 0xfffffff0 + bar++ | 0xf;
+	terminal_writestring("YES HELLO THIS IS KERNEL");
+
+	do_the_set_registers();
 }

src/modules/main/vga.c

@@ -0,0 +1,54 @@
+#include "vga.h"
+
+static const size_t VGA_WIDTH = 80;
+static const size_t VGA_HEIGHT = 25;
+
+static size_t terminal_row;
+static size_t terminal_column;
+static uint8_t terminal_color;
+
+/* Note the use of the volatile keyword to prevent the compiler from eliminating dead stores. */
+static volatile uint16_t* terminal_buffer;
+
+uint8_t vga_entry_color(enum vga_color fg, enum vga_color bg);
+uint16_t vga_entry(unsigned char uc, uint8_t color);
+
+static size_t strlen(const char* str) {
+	size_t len = 0;
+	while (str[len++]);
+	return len;
+}
+
+void terminal_initialize(size_t startrow) {
+	terminal_row = startrow;
+	terminal_column = 0;
+	terminal_color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
+	terminal_buffer = (uint16_t*) 0xB8000;
+}
+
+void terminal_setcolor(uint8_t color) {
+	terminal_color = color;
+}
+
+void terminal_putentryat(char c, uint8_t color, size_t x, size_t y) {
+	const size_t index = y * VGA_WIDTH + x;
+	terminal_buffer[index] = vga_entry(c, color);
+}
+
+void terminal_putchar(char c) {
+	terminal_putentryat(c, terminal_color, terminal_column, terminal_row);
+	if (++terminal_column == VGA_WIDTH) {
+		terminal_column = 0;
+		if (++terminal_row == VGA_HEIGHT)
+			terminal_row = 0;
+	}
+}
+
+void terminal_write(const char* data, size_t size) {
+	for (size_t i = 0; i < size; i++)
+		terminal_putchar(data[i]);
+}
+
+void terminal_writestring(const char* data) {
+	terminal_write(data, strlen(data));
+}

src/modules/main/vga.h

@@ -0,0 +1,38 @@
+#pragma once
+#include <stddef.h>
+#include <stdint.h>
+
+/* Hardware text mode color constants. */
+enum vga_color {
+	VGA_COLOR_BLACK = 0,
+	VGA_COLOR_BLUE = 1,
+	VGA_COLOR_GREEN = 2,
+	VGA_COLOR_CYAN = 3,
+	VGA_COLOR_RED = 4,
+	VGA_COLOR_MAGENTA = 5,
+	VGA_COLOR_BROWN = 6,
+	VGA_COLOR_LIGHT_GREY = 7,
+	VGA_COLOR_DARK_GREY = 8,
+	VGA_COLOR_LIGHT_BLUE = 9,
+	VGA_COLOR_LIGHT_GREEN = 10,
+	VGA_COLOR_LIGHT_CYAN = 11,
+	VGA_COLOR_LIGHT_RED = 12,
+	VGA_COLOR_LIGHT_MAGENTA = 13,
+	VGA_COLOR_LIGHT_BROWN = 14,
+	VGA_COLOR_WHITE = 15,
+};
+
+inline uint8_t vga_entry_color(enum vga_color fg, enum vga_color bg) {
+	return fg | bg << 4;
+}
+
+inline uint16_t vga_entry(unsigned char uc, uint8_t color) {
+	return (uint16_t) uc | (uint16_t) color << 8;
+}
+
+void terminal_initialize(size_t rowstart);
+void terminal_setcolor(uint8_t color);
+void terminal_putentryat(char c, uint8_t color, size_t x, size_t y);
+void terminal_putchar(char c);
+void terminal_write(const char* data, size_t size);
+void terminal_writestring(const char* data);