src/post.c

// 32bit code to Power On Self Test (POST) a machine.
//
// Copyright (C) 2008  Kevin O'Connor <kevin@koconnor.net>
// Copyright (C) 2002  MandrakeSoft S.A.
//
// This file may be distributed under the terms of the GNU GPLv3 license.

#include "ioport.h" // PORT_*
#include "../out/rom16.offset.auto.h" // OFFSET_*
#include "config.h" // CONFIG_*
#include "cmos.h" // CMOS_*
#include "util.h" // memset
#include "biosvar.h" // struct bios_data_area_s
#include "ata.h" // hard_drive_setup
#include "kbd.h" // kbd_setup
#include "disk.h" // floppy_drive_setup
#include "memmap.h" // add_e820
#include "pic.h" // pic_setup

#define bda ((struct bios_data_area_s *)MAKE_FARPTR(SEG_BDA, 0))
#define ebda ((struct extended_bios_data_area_s *)MAKE_FARPTR(SEG_EBDA, 0))

static void
init_bda()
{
    dprintf(3, "init bda\n");
    memset(bda, 0, sizeof(*bda));

    SET_BDA(mem_size_kb, BASE_MEM_IN_K);

    int i;
    for (i=0; i<256; i++) {
        SET_BDA(ivecs[i].seg, SEG_BIOS);
        SET_BDA(ivecs[i].offset, OFFSET_dummy_iret_handler);
    }

    SET_BDA(ivecs[0x08].offset, OFFSET_entry_08);
    SET_BDA(ivecs[0x09].offset, OFFSET_entry_09);
    SET_BDA(ivecs[0x0e].offset, OFFSET_entry_0e);
    SET_BDA(ivecs[0x10].offset, OFFSET_entry_10);
    SET_BDA(ivecs[0x11].offset, OFFSET_entry_11);
    SET_BDA(ivecs[0x12].offset, OFFSET_entry_12);
    SET_BDA(ivecs[0x13].offset, OFFSET_entry_13);
    SET_BDA(ivecs[0x14].offset, OFFSET_entry_14);
    SET_BDA(ivecs[0x15].offset, OFFSET_entry_15);
    SET_BDA(ivecs[0x16].offset, OFFSET_entry_16);
    SET_BDA(ivecs[0x17].offset, OFFSET_entry_17);
    SET_BDA(ivecs[0x18].offset, OFFSET_entry_18);
    SET_BDA(ivecs[0x19].offset, OFFSET_entry_19);
    SET_BDA(ivecs[0x1a].offset, OFFSET_entry_1a);
    SET_BDA(ivecs[0x1c].offset, OFFSET_entry_1c);
    SET_BDA(ivecs[0x40].offset, OFFSET_entry_40);
    SET_BDA(ivecs[0x70].offset, OFFSET_entry_70);
    SET_BDA(ivecs[0x74].offset, OFFSET_entry_74);
    SET_BDA(ivecs[0x75].offset, OFFSET_entry_75);
    SET_BDA(ivecs[0x76].offset, OFFSET_entry_76);

    // set vector 0x79 to zero
    // this is used by 'gardian angel' protection system
    SET_BDA(ivecs[0x79].seg, 0);
    SET_BDA(ivecs[0x79].offset, 0);

    SET_BDA(ivecs[0x1E].offset, OFFSET_diskette_param_table2);
}

static void
init_ebda()
{
    memset(ebda, 0, sizeof(*ebda));
    ebda->size = EBDA_SIZE;
    SET_BDA(ebda_seg, SEG_EBDA);
    SET_BDA(ivecs[0x41].seg, SEG_EBDA);
    SET_BDA(ivecs[0x41].offset
            , offsetof(struct extended_bios_data_area_s, fdpt[0]));
    SET_BDA(ivecs[0x46].seg, SEG_EBDA);
    SET_BDA(ivecs[0x41].offset
            , offsetof(struct extended_bios_data_area_s, fdpt[1]));
}

static void
ram_probe(void)
{
    dprintf(3, "Find memory size\n");
    if (CONFIG_COREBOOT) {
        coreboot_fill_map();
    } else {
        // On emulators, get memory size from nvram.
        u32 rs = (inb_cmos(CMOS_MEM_EXTMEM2_LOW)
                  | (inb_cmos(CMOS_MEM_EXTMEM2_HIGH) << 8)) * 65536;
        if (rs)
            rs += 16 * 1024 * 1024;
        else
            rs = ((inb_cmos(CMOS_MEM_EXTMEM_LOW)
                   | (inb_cmos(CMOS_MEM_EXTMEM_HIGH) << 8)) * 1024
                  + 1 * 1024 * 1024);
        SET_EBDA(ram_size, rs);
        add_e820(0, rs, E820_RAM);

        /* reserve 256KB BIOS area at the end of 4 GB */
        add_e820(0xfffc0000, 256*1024, E820_RESERVED);
    }

    // Don't declare any memory between 0xa0000 and 0x100000
    add_e820(0xa0000, 0x50000, E820_HOLE);

    // Mark known areas as reserved.
    add_e820((u32)MAKE_FARPTR(SEG_EBDA, 0), EBDA_SIZE * 1024, E820_RESERVED);
    add_e820((u32)MAKE_FARPTR(SEG_BIOS, 0), 0x10000, E820_RESERVED);

    dprintf(1, "ram_size=0x%08x\n", GET_EBDA(ram_size));
}

static void
init_boot_vectors()
{
    dprintf(3, "init boot device ordering\n");

    // Floppy drive
    struct ipl_entry_s *ip = &ebda->ipl.table[0];
    ip->type = IPL_TYPE_FLOPPY;
    ip++;

    // First HDD
    ip->type = IPL_TYPE_HARDDISK;
    ip++;

    // CDROM
    if (CONFIG_CDROM_BOOT) {
        ip->type = IPL_TYPE_CDROM;
        ip++;
    }

    ebda->ipl.count = ip - ebda->ipl.table;
    ebda->ipl.sequence = 0xffff;
    if (CONFIG_COREBOOT) {
        // XXX - hardcode defaults for coreboot.
        ebda->ipl.bootorder = 0x00000231;
        ebda->ipl.checkfloppysig = 1;
    } else {
        // On emulators, get boot order from nvram.
        ebda->ipl.bootorder = (inb_cmos(CMOS_BIOS_BOOTFLAG2)
                               | ((inb_cmos(CMOS_BIOS_BOOTFLAG1) & 0xf0) << 4));
        if (!(inb_cmos(CMOS_BIOS_BOOTFLAG1) & 1))
            ebda->ipl.checkfloppysig = 1;
    }
}

// Execute a given option rom.
static void
callrom(u16 seg, u16 offset)
{
    struct bregs br;
    memset(&br, 0, sizeof(br));
    br.es = SEG_BIOS;
    br.di = OFFSET_pnp_string + 1; // starts 1 past for alignment
    br.cs = seg;
    br.ip = offset;
    call16(&br);

    debug_serial_setup();
}

// Find and run any "option roms" found in the given address range.
static void
rom_scan(u32 start, u32 end)
{
    u8 *p = (u8*)start;
    for (; p <= (u8*)end; p += 2048) {
        u8 *rom = p;
        if (*(u16*)rom != 0xaa55)
            continue;
        u32 len = rom[2] * 512;
        u8 sum = checksum(rom, len);
        if (sum != 0) {
            dprintf(1, "Found option rom with bad checksum:"
                    " loc=%p len=%d sum=%x\n"
                    , rom, len, sum);
            continue;
        }
        p = (u8*)(((u32)p + len) / 2048 * 2048);
        dprintf(1, "Running option rom at %p\n", rom+3);
        callrom(FARPTR_TO_SEG(rom), FARPTR_TO_OFFSET(rom + 3));

        if (GET_BDA(ebda_seg) != SEG_EBDA)
            BX_PANIC("Option rom at %p attempted to move ebda from %x to %x\n"
                     , rom, SEG_EBDA, GET_BDA(ebda_seg));

        // Look at the ROM's PnP Expansion header.  Properly, we're supposed
        // to init all the ROMs and then go back and build an IPL table of
        // all the bootable devices, but we can get away with one pass.
        if (rom[0x1a] != '$' || rom[0x1b] != 'P'
            || rom[0x1c] != 'n' || rom[0x1d] != 'P')
            continue;
        // 0x1A is also the offset into the expansion header of...
        // the Bootstrap Entry Vector, or zero if there is none.
        u16 entry = *(u16*)&rom[0x1a+0x1a];
        if (!entry)
            continue;
        // Found a device that thinks it can boot the system.  Record
        // its BEV and product name string.

        if (ebda->ipl.count >= ARRAY_SIZE(ebda->ipl.table))
            continue;

        struct ipl_entry_s *ip = &ebda->ipl.table[ebda->ipl.count];
        ip->type = IPL_TYPE_BEV;
        ip->vector = (FARPTR_TO_SEG(rom) << 16) | entry;

        u16 desc = *(u16*)&rom[0x1a+0x10];
        if (desc)
            ip->description = (u32)MAKE_FARPTR(FARPTR_TO_SEG(rom), desc);

        ebda->ipl.count++;
    }
}

// Main setup code.
static void
post()
{
    init_bda();
    init_ebda();

    pic_setup();
    timer_setup();
    kbd_setup();
    lpt_setup();
    serial_setup();
    mouse_setup();
    mathcp_setup();

    memmap_setup();

    ram_probe();

    dprintf(1, "Scan for VGA option rom\n");
    rom_scan(0xc0000, 0xc7800);

    printf("BIOS - begin\n\n");

    rombios32_init();

    memmap_finalize();

    floppy_drive_setup();
    hard_drive_setup();

    init_boot_vectors();

    dprintf(1, "Scan for option roms\n");
    rom_scan(0xc8000, 0xe0000);
}

// Clear .bss section for C code.
static void
clear_bss()
{
    dprintf(3, "clearing .bss section\n");
    extern char __bss_start[], __bss_end[];
    memset(__bss_start, 0, __bss_end - __bss_start);
}

// Reset DMA controller
static void
init_dma()
{
    // first reset the DMA controllers
    outb(0, PORT_DMA1_MASTER_CLEAR);
    outb(0, PORT_DMA2_MASTER_CLEAR);

    // then initialize the DMA controllers
    outb(0xc0, PORT_DMA2_MODE_REG);
    outb(0x00, PORT_DMA2_MASK_REG);
}

// Check if the machine was setup with a special restart vector.
static void
check_restart_status()
{
    // Get and then clear CMOS shutdown status.
    u8 status = inb_cmos(CMOS_RESET_CODE);
    outb_cmos(0, CMOS_RESET_CODE);

    if (status == 0x00 || status == 0x09 || status >= 0x0d)
        // Normal post
        return;

    if (status != 0x05) {
        BX_PANIC("Unimplemented shutdown status: %02x\n", status);
        return;
    }

    // XXX - this is supposed to jump without changing any memory -
    // but the stack has been altered by the time the code gets here.
    eoi_pic2();
    struct bregs br;
    memset(&br, 0, sizeof(br));
    br.cs = GET_BDA(jump_cs_ip) >> 16;
    br.ip = GET_BDA(jump_cs_ip);
    call16(&br);
}

// 32-bit entry point.
void VISIBLE32
_start()
{
    init_dma();
    check_restart_status();

    debug_serial_setup();
    dprintf(1, "Start bios\n");

    // Setup for .bss and .data sections
    clear_bss();
    make_bios_writable();

    // Perform main setup code.
    post();

    // Present the user with a bootup menu.
    interactive_bootmenu();

    // Prep for boot process.
    make_bios_readonly();
    clear_bss();

    // Invoke int 19 to start boot process.
    dprintf(3, "Jump to int19\n");
    struct bregs br;
    memset(&br, 0, sizeof(br));
    call16_int(0x19, &br);
}

// Externally visible 32bit entry point.
asm(
    ".global post32\n"
    "post32:\n"
    "cli\n"
    "cld\n"
    "lidtl " __stringify(0xf0000 | OFFSET_pmode_IDT_info) "\n"
    "lgdtl " __stringify(0xf0000 | OFFSET_rombios32_gdt_48) "\n"
    "movl $" __stringify(BUILD_STACK_ADDR) ", %esp\n"
    "ljmp $0x10, $_start\n"
    );