From d51fff2d9d6f2494b0c04b8b3a3681f2bf5e7319 Mon Sep 17 00:00:00 2001 From: Mathieu Maret Date: Sun, 5 Aug 2018 15:09:32 +0200 Subject: [PATCH] Retrieve multiboot information from bootloader --- boot.asm | 10 ++ boot.s | 9 ++ core/main.c | 32 +++++- core/multiboot.h | 263 +++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 313 insertions(+), 1 deletion(-) create mode 100644 core/multiboot.h diff --git a/boot.asm b/boot.asm index 664f5e2..ed48094 100644 --- a/boot.asm +++ b/boot.asm @@ -73,6 +73,16 @@ _start: ; stack since (pushed 0 bytes so far) and the alignment is thus ; preserved and the call is well defined. ; note, that if you are building on Windows, C functions may have "_" prefix in assembly: _kernel_main + + ; Reset EFLAGS. + push dword 0 + popf + + ; Push the pointer to the Multiboot information structure. + push ebx + ; Push the magic value. + push eax + extern kmain call kmain diff --git a/boot.s b/boot.s index 2ebf558..27f32f6 100644 --- a/boot.s +++ b/boot.s @@ -77,6 +77,11 @@ _start: runtime support to work as well. */ + /* Reset EFLAGS. */ + pushl $0 + popf + + /* Enter the high-level kernel. The ABI requires the stack is 16-byte aligned at the time of the call instruction (which afterwards pushes @@ -85,6 +90,10 @@ _start: stack since (pushed 0 bytes so far) and the alignment is thus preserved and the call is well defined. */ + /* Push the pointer to the Multiboot information structure. */ + pushl %ebx + /* Push the magic value. */ + pushl %eax call kmain /* diff --git a/core/main.c b/core/main.c index 12f5841..f7eca30 100644 --- a/core/main.c +++ b/core/main.c @@ -4,16 +4,20 @@ #include "interrupt.h" #include "io.h" #include "irq.h" +#include "multiboot.h" #include "pit.h" #include "types.h" #include "vga.h" +#define CHECK_FLAG(flags,bit) ((flags) & (1 << (bit))) void cpuid(int code, uint32_t *a, uint32_t *d) { asm volatile("cpuid" : "=a"(*a), "=d"(*d) : "0"(code) : "ebx", "ecx"); } -void kmain() + +// Multiboot information available here : https://www.gnu.org/software/grub/manual/multiboot/multiboot.html#kernel_002ec +void kmain(unsigned long magic, unsigned long addr) { initVGA(BLACK, GREEN); printString("Setting up IDT\n"); @@ -22,6 +26,32 @@ void kmain() irqSetup(); initPit(100); + if (magic == MULTIBOOT_BOOTLOADER_MAGIC) { // Get loaded by Grub wuth mutliboot version 1 + multiboot_info_t *mbi = (multiboot_info_t *)addr; + /* Are mem_* valid? */ + if (CHECK_FLAG(mbi->flags, 0)){ + printString("mem_lower = "); + printInt((unsigned)mbi->mem_lower); + printString("KB mem_upper = "); + printInt((unsigned)mbi->mem_upper); + printString("KB\n"); + } + + /* Is boot_device valid? */ + if (CHECK_FLAG(mbi->flags, 1)){ + printString("boot_device = "); + printInt((unsigned)mbi->boot_device); + printString("\n"); + } + + /* Is the command line passed? */ + if (CHECK_FLAG(mbi->flags, 2)){ + printString("cmdline = "); + printString((char *)mbi->cmdline); + printString("\n"); + } + } + printString("Setting up IRQ handlers\n"); irqSetRoutine(IRQ_KEYBOARD, keyboard_handler); irqSetRoutine(IRQ_TIMER, timer_handler); diff --git a/core/multiboot.h b/core/multiboot.h new file mode 100644 index 0000000..0ee4acc --- /dev/null +++ b/core/multiboot.h @@ -0,0 +1,263 @@ +// Taken from https://www.gnu.org/software/grub/manual/multiboot/multiboot.html#multiboot_002eh +/* multiboot.h - Multiboot header file. */ +/* Copyright (C) 1999,2003,2007,2008,2009,2010 Free Software Foundation, Inc. + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to + * deal in the Software without restriction, including without limitation the + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or + * sell copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL ANY + * DEVELOPER OR DISTRIBUTOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, + * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR + * IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + */ + +#ifndef MULTIBOOT_HEADER +#define MULTIBOOT_HEADER 1 + +/* How many bytes from the start of the file we search for the header. */ +#define MULTIBOOT_SEARCH 8192 +#define MULTIBOOT_HEADER_ALIGN 4 + +/* The magic field should contain this. */ +#define MULTIBOOT_HEADER_MAGIC 0x1BADB002 + +/* This should be in %eax. */ +#define MULTIBOOT_BOOTLOADER_MAGIC 0x2BADB002 + +/* Alignment of multiboot modules. */ +#define MULTIBOOT_MOD_ALIGN 0x00001000 + +/* Alignment of the multiboot info structure. */ +#define MULTIBOOT_INFO_ALIGN 0x00000004 + +/* Flags set in the 'flags' member of the multiboot header. */ + +/* Align all boot modules on i386 page (4KB) boundaries. */ +#define MULTIBOOT_PAGE_ALIGN 0x00000001 + +/* Must pass memory information to OS. */ +#define MULTIBOOT_MEMORY_INFO 0x00000002 + +/* Must pass video information to OS. */ +#define MULTIBOOT_VIDEO_MODE 0x00000004 + +/* This flag indicates the use of the address fields in the header. */ +#define MULTIBOOT_AOUT_KLUDGE 0x00010000 + +/* Flags to be set in the 'flags' member of the multiboot info structure. */ + +/* is there basic lower/upper memory information? */ +#define MULTIBOOT_INFO_MEMORY 0x00000001 +/* is there a boot device set? */ +#define MULTIBOOT_INFO_BOOTDEV 0x00000002 +/* is the command-line defined? */ +#define MULTIBOOT_INFO_CMDLINE 0x00000004 +/* are there modules to do something with? */ +#define MULTIBOOT_INFO_MODS 0x00000008 + +/* These next two are mutually exclusive */ + +/* is there a symbol table loaded? */ +#define MULTIBOOT_INFO_AOUT_SYMS 0x00000010 +/* is there an ELF section header table? */ +#define MULTIBOOT_INFO_ELF_SHDR 0X00000020 + +/* is there a full memory map? */ +#define MULTIBOOT_INFO_MEM_MAP 0x00000040 + +/* Is there drive info? */ +#define MULTIBOOT_INFO_DRIVE_INFO 0x00000080 + +/* Is there a config table? */ +#define MULTIBOOT_INFO_CONFIG_TABLE 0x00000100 + +/* Is there a boot loader name? */ +#define MULTIBOOT_INFO_BOOT_LOADER_NAME 0x00000200 + +/* Is there a APM table? */ +#define MULTIBOOT_INFO_APM_TABLE 0x00000400 + +/* Is there video information? */ +#define MULTIBOOT_INFO_VBE_INFO 0x00000800 +#define MULTIBOOT_INFO_FRAMEBUFFER_INFO 0x00001000 + +#ifndef ASM_FILE + +typedef unsigned char multiboot_uint8_t; +typedef unsigned short multiboot_uint16_t; +typedef unsigned int multiboot_uint32_t; +typedef unsigned long long multiboot_uint64_t; + +struct multiboot_header { + /* Must be MULTIBOOT_MAGIC - see above. */ + multiboot_uint32_t magic; + + /* Feature flags. */ + multiboot_uint32_t flags; + + /* The above fields plus this one must equal 0 mod 2^32. */ + multiboot_uint32_t checksum; + + /* These are only valid if MULTIBOOT_AOUT_KLUDGE is set. */ + multiboot_uint32_t header_addr; + multiboot_uint32_t load_addr; + multiboot_uint32_t load_end_addr; + multiboot_uint32_t bss_end_addr; + multiboot_uint32_t entry_addr; + + /* These are only valid if MULTIBOOT_VIDEO_MODE is set. */ + multiboot_uint32_t mode_type; + multiboot_uint32_t width; + multiboot_uint32_t height; + multiboot_uint32_t depth; +}; + +/* The symbol table for a.out. */ +struct multiboot_aout_symbol_table { + multiboot_uint32_t tabsize; + multiboot_uint32_t strsize; + multiboot_uint32_t addr; + multiboot_uint32_t reserved; +}; +typedef struct multiboot_aout_symbol_table multiboot_aout_symbol_table_t; + +/* The section header table for ELF. */ +struct multiboot_elf_section_header_table { + multiboot_uint32_t num; + multiboot_uint32_t size; + multiboot_uint32_t addr; + multiboot_uint32_t shndx; +}; +typedef struct multiboot_elf_section_header_table multiboot_elf_section_header_table_t; + +struct multiboot_info { + /* Multiboot info version number */ + multiboot_uint32_t flags; + + /* Available memory from BIOS */ + multiboot_uint32_t mem_lower; + multiboot_uint32_t mem_upper; + + /* "root" partition */ + multiboot_uint32_t boot_device; + + /* Kernel command line */ + multiboot_uint32_t cmdline; + + /* Boot-Module list */ + multiboot_uint32_t mods_count; + multiboot_uint32_t mods_addr; + + union { + multiboot_aout_symbol_table_t aout_sym; + multiboot_elf_section_header_table_t elf_sec; + } u; + + /* Memory Mapping buffer */ + multiboot_uint32_t mmap_length; + multiboot_uint32_t mmap_addr; + + /* Drive Info buffer */ + multiboot_uint32_t drives_length; + multiboot_uint32_t drives_addr; + + /* ROM configuration table */ + multiboot_uint32_t config_table; + + /* Boot Loader Name */ + multiboot_uint32_t boot_loader_name; + + /* APM table */ + multiboot_uint32_t apm_table; + + /* Video */ + multiboot_uint32_t vbe_control_info; + multiboot_uint32_t vbe_mode_info; + multiboot_uint16_t vbe_mode; + multiboot_uint16_t vbe_interface_seg; + multiboot_uint16_t vbe_interface_off; + multiboot_uint16_t vbe_interface_len; + + multiboot_uint64_t framebuffer_addr; + multiboot_uint32_t framebuffer_pitch; + multiboot_uint32_t framebuffer_width; + multiboot_uint32_t framebuffer_height; + multiboot_uint8_t framebuffer_bpp; +#define MULTIBOOT_FRAMEBUFFER_TYPE_INDEXED 0 +#define MULTIBOOT_FRAMEBUFFER_TYPE_RGB 1 +#define MULTIBOOT_FRAMEBUFFER_TYPE_EGA_TEXT 2 + multiboot_uint8_t framebuffer_type; + union { + struct { + multiboot_uint32_t framebuffer_palette_addr; + multiboot_uint16_t framebuffer_palette_num_colors; + }; + struct { + multiboot_uint8_t framebuffer_red_field_position; + multiboot_uint8_t framebuffer_red_mask_size; + multiboot_uint8_t framebuffer_green_field_position; + multiboot_uint8_t framebuffer_green_mask_size; + multiboot_uint8_t framebuffer_blue_field_position; + multiboot_uint8_t framebuffer_blue_mask_size; + }; + }; +}; +typedef struct multiboot_info multiboot_info_t; + +struct multiboot_color { + multiboot_uint8_t red; + multiboot_uint8_t green; + multiboot_uint8_t blue; +}; + +struct multiboot_mmap_entry { + multiboot_uint32_t size; + multiboot_uint64_t addr; + multiboot_uint64_t len; +#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 + multiboot_uint32_t type; +} __attribute__((packed)); +typedef struct multiboot_mmap_entry multiboot_memory_map_t; + +struct multiboot_mod_list { + /* the memory used goes from bytes 'mod_start' to 'mod_end-1' inclusive */ + multiboot_uint32_t mod_start; + multiboot_uint32_t mod_end; + + /* Module command line */ + multiboot_uint32_t cmdline; + + /* padding to take it to 16 bytes (must be zero) */ + multiboot_uint32_t pad; +}; +typedef struct multiboot_mod_list multiboot_module_t; + +/* APM BIOS info. */ +struct multiboot_apm_info { + multiboot_uint16_t version; + multiboot_uint16_t cseg; + multiboot_uint32_t offset; + multiboot_uint16_t cseg_16; + multiboot_uint16_t dseg; + multiboot_uint16_t flags; + multiboot_uint16_t cseg_len; + multiboot_uint16_t cseg_16_len; + multiboot_uint16_t dseg_len; +}; + +#endif /* ! ASM_FILE */ + +#endif /* ! MULTIBOOT_HEADER */