multiboot info, serial ports, logs

Makefile

@@ -4,15 +4,17 @@ AS = nasm
 BUILDDIR := build
 INCLUDEDIR := include
 
-CFLAGS   := -ffreestanding -Wall -Wextra -Werror -I $(INCLUDEDIR)
-LDFLAGS  := -ffreestanding -nostdlib -lgcc -T kernel/kernel.ld
-
 KSRC := $(wildcard kernel/*.asm kernel/*.c)
 KOBJ := $(addprefix $(BUILDDIR)/, \
 		$(notdir \
 		$(patsubst %.asm,%.o, $(patsubst %.c,%.o, $(KSRC)))))
 KIMG := kernel.bin
 
+CFLAGS    := -ffreestanding -Wall -Wextra -Werror -I $(INCLUDEDIR)
+LDFLAGS   := -ffreestanding -nostdlib -lgcc -T kernel/kernel.ld
+QEMUFLAGS := -kernel $(BUILDDIR)/$(KIMG) \
+	     -serial stdio
+
 $(BUILDDIR)/$(KIMG): $(KOBJ)
 	$(CC) $^ -o $@ $(LDFLAGS)
 $(BUILDDIR)/%.o: */%.asm
@@ -27,7 +29,7 @@ $(BUILDDIR)/Hazel.iso: kernel
 	grub-mkrescue -o  $(BUILDDIR)/Hazel.iso .
 
 qemu: kernel
-	qemu-system-i386 -kernel $(BUILDDIR)/$(KIMG)
+	qemu-system-i386 $(QEMUFLAGS)
 
 clean:
 	rm build/* boot/*.bin

compile_commands.json

@@ -0,0 +1,20 @@
+[
+  {
+    "arguments": [
+      "/home/rami/crossdev/bin/i686-elf-gcc",
+      "-ffreestanding",
+      "-Wall",
+      "-Wextra",
+      "-Werror",
+      "-I",
+      "include",
+      "-c",
+      "-o",
+      "build/kernel.o",
+      "kernel/kernel.c"
+    ],
+    "directory": "/home/rami/hazel",
+    "file": "/home/rami/hazel/kernel/kernel.c",
+    "output": "/home/rami/hazel/build/kernel.o"
+  }
+]

include/kernel/io.h

@@ -0,0 +1,9 @@
+#ifndef HAZEL_IO_H_
+#define HAZEL_IO_H_
+
+#include <stdint.h>
+
+uint8_t inb(uint16_t port);
+void outb(uint16_t port, uint8_t byte);
+
+#endif

include/kernel/kernel.h

@@ -0,0 +1,15 @@
+#ifndef HAZEL_KERNEL_H_
+#define HAZEL_KERNEL_H_
+
+#include <kernel/multiboot.h>
+#include <kernel/log.h>
+
+#define cpu_relax asm volatile ("pause" ::)
+
+typedef struct {
+   multiboot_memory_map_t *mem_map;
+   uint32_t mem_map_len;
+   log_method_t log_method;
+} kernel_ctx_t;
+
+#endif

include/kernel/log.h

@@ -0,0 +1,13 @@
+#ifndef HAZEL_LOG_H_
+#define HAZEL_LOG_H_
+
+typedef enum {
+    LOG_COM1,
+    LOG_VGA,
+} log_method_t;
+
+#define LOG(x) logs(x);
+
+void logs(const char *str);
+
+#endif

include/kernel/multiboot.h

@@ -26,4 +26,21 @@ typedef struct {
     uint32_t vbeinterfacelength;
 } multiboot_info_t; 
 
+struct multiboot_mmap_entry
+{
+    uint32_t size;
+    uint32_t addr_low;
+    uint32_t addr_high;
+    uint32_t len_low;
+    uint32_t len_high;
+#define MULTIBOOT_MEMORY_AVAILABLE              1
+#define MULTIBOOT_MEMORY_RESERVED               2
+#define MULTIBOOT_MEMORY_ACPI_RECLAIMABLE       3
+#define MULTIBOOT_MEMORY_NVS                    4
+#define MULTIBOOT_MEMORY_BADRAM                 5
+    uint32_t type;
+} __attribute__((packed));
+typedef struct multiboot_mmap_entry multiboot_memory_map_t;
+
+
 #endif

include/kernel/serial.h

@@ -0,0 +1,21 @@
+#ifndef HAZEL_SERIAL_H_
+#define HAZEL_SERIAL_H_
+
+#include <stdint.h>
+
+#define COM1 0x3F8
+#define COM2 0x2F8
+#define COM3 0x3E8
+#define COM4 0x2E8
+#define COM5 0x5F8
+#define COM6 0x4F8
+#define COM7 0x5E8
+#define COM8 0x4E8
+
+#define IS_TRANSMIT_EMPTY(x) (inb(x + 5) & 0x20)
+
+uint8_t serial_port_init(int port);
+void serial_putc(int port, const char c);
+void serial_puts(int port, const char *str);
+
+#endif

kernel/io.c

@@ -0,0 +1,17 @@
+#include <kernel/io.h>
+
+uint8_t inb(uint16_t port) {
+    uint8_t result;
+
+    asm volatile ("in %%dx, %%al"
+            : "=a" (result)
+            : "d"  (port));
+
+    return result;
+}
+
+void outb(uint16_t port, uint8_t byte) {
+    asm volatile ("out %%al, %%dx"
+            : // no output
+            : "a" (byte), "d" (port));
+}

kernel/kernel.c

@@ -1,10 +1,19 @@
+#include <kernel/kernel.h>
 #include <kernel/multiboot.h>
+#include <kernel/serial.h>
+
+kernel_ctx_t ctx = {0};
 
 void kernel(multiboot_info_t *info) {
-	char *vmem = (char *)0xb8000;
-	vmem[0] = info->flags; 
-	vmem[1] = 0x0f;
+    if (!(info->flags & (1<<6))) goto halt;
+    ctx.mem_map = (multiboot_memory_map_t *)info->memmapaddress;
+    ctx.mem_map_len = info->memmaplength;
 
+    if (serial_port_init(COM1))
+	ctx.log_method = LOG_COM1;
+
+    LOG("Kernel log being sent to COM1\n");
+halt:
     asm volatile ("cli" ::);
     for (;;) {}
 }

kernel/log.c

@@ -0,0 +1,15 @@
+#include <kernel/log.h>
+#include <kernel/kernel.h>
+#include <kernel/serial.h>
+
+extern kernel_ctx_t ctx;
+
+void logs(const char *str) {
+    switch (ctx.log_method) {
+	case LOG_COM1:
+	    serial_puts(COM1, str);
+	    break;
+	default:
+	    break;
+    }
+}

kernel/serial.c

@@ -0,0 +1,44 @@
+#include <kernel/serial.h>
+#include <kernel/io.h>
+#include <kernel/kernel.h>
+
+uint8_t serial_port_init(int port) {
+    // Test port by seeing if scratch register can store a value
+    uint8_t old_scratch = inb(port + 7);
+    outb(port + 7, old_scratch + 1);
+    if (inb(port + 7) != old_scratch + 1)
+	return 0;
+    outb(port + 7, old_scratch);
+
+    outb(port + 1, 0x00);    // Disable all interrupts
+    outb(port + 3, 0x80);    // Enable DLAB (set baud rate divisor)
+    outb(port + 0, 0x03);    // Set divisor to 3 (lo byte) 38400 baud
+    outb(port + 1, 0x00);    //                  (hi byte)
+    outb(port + 3, 0x03);    // 8 bits, no parity, one stop bit
+    outb(port + 2, 0xC7);    // Enable FIFO, clear them, with 14-byte threshold
+    outb(port + 4, 0x0B);    // IRQs enabled, RTS/DSR set
+    outb(port + 4, 0x1E);    // Set in loopback mode, test the serial chip
+    outb(port + 0, 0xAE);    // Test serial chip (send byte 0xAE and check if serial returns same byte)
+
+    // Check if serial is faulty (i.e: not same byte as sent)
+    if(inb(port + 0) != 0xAE)
+	return 0;
+
+    // If serial is not faulty set it in normal operation mode
+    // (not-loopback with IRQs enabled and OUT#1 and OUT#2 bits enabled)
+    outb(port + 4, 0x0F);
+    return 1;
+}
+
+void serial_putc(int port, const char c) {
+    // Poll until transmit is empty
+    while(!IS_TRANSMIT_EMPTY(port)) cpu_relax;
+    outb(port, c);
+}
+
+void serial_puts(int port, const char *str) {
+    while (*str) {
+	serial_putc(port, str[0]); 
+	str++;
+    }
+}