fix: memory layout and startup

kernel/Makefile

@@ -6,7 +6,7 @@ output_dir := $(root_dir)/output
 
 LD := ld
 CXX := clang++
-CXXFLAGS := -std=c++20 -fpie -fno-strict-aliasing -fno-stack-protector -fno-asynchronous-unwind-tables -fno-exceptions -fno-rtti -fno-common -mno-red-zone -mgeneral-regs-only -ffreestanding -Og -g -Wall -Wextra -Wno-reserved-identifier -I$(root_dir)/include
+CXXFLAGS := -std=c++20 -fpie -fno-strict-aliasing -fno-stack-protector -fno-asynchronous-unwind-tables -fno-exceptions -fno-rtti -fno-common -mno-red-zone -mgeneral-regs-only -ffreestanding -O2 -g -Wall -Wextra -Wno-reserved-identifier -I$(root_dir)/include
 
 source_files := $(shell find $(source_dir) -type f -name "*.cpp")
 object_files := $(patsubst $(source_dir)/%,$(object_dir)/%.o,$(source_files))
@@ -23,6 +23,10 @@ kernel.bin: $(object_files)
 	@echo "Disassembling kernel"
 	@objdump -dC $(output_dir)/kernel.bin > $(output_dir)/kernel.asm
 	@objdump -DC $(output_dir)/kernel.bin > $(output_dir)/kernel_full.asm
+	@echo "Dumping strings"
+	@strings -t x $(output_dir)/kernel.bin > $(output_dir)/kernel.strings
+	@echo "Hexdumping sections"
+	@objdump -sC $(output_dir)/kernel.bin > $(output_dir)/kernel.hex
 
 
 iso: kernel.bin

kernel/include/init/multiboot2.h

@@ -245,7 +245,7 @@ struct info {
 
 inline info* get_multiboot_info() {
     auto addr = read_symbol("__multiboot_info");
-    uint32_t phys = *paddr_t{addr}.access<uint32_t>();
+    uint32_t phys = *paddr_t{addr}.access<volatile uint32_t>();
     return paddr_t{phys}.access<info>();
 }
 

kernel/include/init/print.h

@@ -32,6 +32,7 @@ struct TextAttr {
     }
 };
 
+void initFromLow();
 void clear();
 void print(const char* str, TextAttr attr = {});
 void print_dec(uint64_t value, TextAttr attr = {});

kernel/linker.ld

@@ -1,6 +1,8 @@
 
 ENTRY(__start)
 
+high_base = 0xFFFF800000000000;
+
 MEMORY
 {
     MULTIBOOT_HEADER_PV : ORIGIN = 16k, LENGTH = 4k
@@ -9,7 +11,7 @@ MEMORY
 
     KERNEL_MEMORY_P : ORIGIN = 64k, LENGTH = (1024M - ORIGIN(KERNEL_MEMORY_P))
 
-    HIGH_KERNEL_V : ORIGIN = 0xFFFF800000000000 + 64k, LENGTH = LENGTH(KERNEL_MEMORY_P)
+    HIGH_KERNEL_V : ORIGIN = high_base + ORIGIN(KERNEL_MEMORY_P), LENGTH = LENGTH(KERNEL_MEMORY_P)
 }
 
 SECTIONS
@@ -29,31 +31,31 @@ SECTIONS
         KEEP(*(.startup_data))
         __startup_data_end__ = .;
     } > START_MEMORY_PV
-    .text : {
+    .text : AT(ADDR(.text) - high_base) {
         __text_start__ = .;
         *(EXCLUDE_FILE(*trampoline*) .text)
         __text_end__ = .;
-    } > HIGH_KERNEL_V AT > KERNEL_MEMORY_P
+    } > HIGH_KERNEL_V
-    .rodata : {
+    .rodata : AT(ADDR(.rodata) - high_base) {
         __rodata_start__ = .;
         *(EXCLUDE_FILE(*trampoline*) .rodata)
         __rodata_end__ = .;
-    } > HIGH_KERNEL_V AT > KERNEL_MEMORY_P
+    } > HIGH_KERNEL_V
-    .data : {
+    .data : AT(ADDR(.data) - high_base) {
         __data_start__ = .;
         *(EXCLUDE_FILE(*trampoline*) .data)
         __data_end__ = .;
-    } > HIGH_KERNEL_V AT > KERNEL_MEMORY_P
+    } > HIGH_KERNEL_V
-    .bss : {
+    .reserved_ranges : AT(ADDR(.reserved_ranges) - high_base) {
-        __bss_start__ = .;
-        *(EXCLUDE_FILE(*trampoline*) .bss)
-        __bss_end__ = .;
-    } > HIGH_KERNEL_V AT > KERNEL_MEMORY_P
-    .reserved_ranges : {
         __reserved_ranges_start__ = .;
         KEEP(*(.reserved_ranges))
         __reserved_ranges_end__ = .;
-    } > HIGH_KERNEL_V AT > KERNEL_MEMORY_P
+    } > HIGH_KERNEL_V
+    .bss (NOLOAD) : AT(ADDR(.bss) - high_base) {
+        __bss_start__ = .;
+        *(EXCLUDE_FILE(*trampoline*) .bss)
+        __bss_end__ = .;
+    } > HIGH_KERNEL_V
 
     .trampoline_text : {
         __trampoline_text_start__ = .;
@@ -67,18 +69,18 @@ SECTIONS
         __trampoline_data_end__ = .;
     } > TRAMPOLINE_PV
 
-    .trampoline_bss : {
-        __trampoline_bss_start__ = .;
-        *trampoline*(.bss)
-        __trampoline_bss_end__ = .;
-    } > TRAMPOLINE_PV
-
     .trampoline_rodata : {
         __trampoline_rodata_start__ = .;
         *trampoline*(.rodata)
         __trampoline_rodata_end__ = .;
     } > TRAMPOLINE_PV
 
+    .trampoline_bss (NOLOAD) : {
+        __trampoline_bss_start__ = .;
+        *trampoline*(.bss)
+        __trampoline_bss_end__ = .;
+    } > TRAMPOLINE_PV
+
     /DISCARD/ : {
         *(.comment)
         *(.eh_frame)

kernel/src/init/init.cpp

@@ -45,7 +45,8 @@ static void loadMultiboot() {
 }
 
 [[maybe_unused]] [[noreturn]] __attribute__((used)) void init() {
+    initFromLow();
     print("Reached init\n", {});
-    //step("multiboot", loadMultiboot);
+    step("multiboot", loadMultiboot);
     halt();
 }

kernel/src/init/print.cpp

@@ -11,17 +11,14 @@ static constexpr int      HEX_TOP_SHIFT   = (sizeof(uint64_t) * 8) - HEX_BITS;
 
 static const char hex_chars[] = "0123456789ABCDEF";
 
-static volatile uint32_t* cursor() {
+static uint32_t cursor;
-    auto cursor_addr = read_symbol("__cursor");
-    return paddr_t{cursor_addr}.access<volatile uint32_t>();
-}
 
 static volatile uint16_t* vga_cell(uint32_t offset) {
     return paddr_t{VGA_PHYS_BASE + offset}.access<volatile uint16_t>();
 }
 
 static void next_line() {
-    *cursor() = ((*cursor() + BYTES_PER_ROW - 1) / BYTES_PER_ROW) * BYTES_PER_ROW;
+    cursor = ((cursor + BYTES_PER_ROW - 1) / BYTES_PER_ROW) * BYTES_PER_ROW;
 }
 
 static void put_char(char ch, uint16_t attr_word) {
@@ -29,12 +26,17 @@ static void put_char(char ch, uint16_t attr_word) {
         next_line();
         return;
     }
-    *vga_cell(*cursor()) = attr_word | (uint8_t)ch;
+    *vga_cell(cursor) = attr_word | (uint16_t)ch;
-    *cursor() += BYTES_PER_CELL;
+    cursor += BYTES_PER_CELL;
+}
+
+void initFromLow () {
+    auto __cursor = read_symbol("__cursor");
+    cursor = *paddr_t{__cursor}.access<volatile uint32_t>();
 }
 
 void clear() {
-    *cursor() = 0;
+    cursor = 0;
     for (int i = 0; i < VGA_COLS * VGA_ROWS; i++) {
         *vga_cell(i * BYTES_PER_CELL) = 0;
     }

kernel/src/startup/entry.cpp

@@ -141,6 +141,12 @@ __clear:
     mov $0xb8000, %edi
     mov $0x2000, %ecx
     rep stosw
+    mov $0x3D4, %dx
+    mov $0x0A, %al
+    out %al, %dx
+    inc %dx
+    mov $0x20, %al
+    out %al, %dx
     ret
 
 __print: