91 lines
2.0 KiB
C
91 lines
2.0 KiB
C
#include <stddef.h>
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#include <stdint.h>
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#include <protos/chainload.h>
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#include <lib/part.h>
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#include <lib/config.h>
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#include <lib/blib.h>
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#include <drivers/disk.h>
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#include <lib/term.h>
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#include <mm/mtrr.h>
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__attribute__((section(".realmode"), used))
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static void spinup(uint8_t drive) {
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asm volatile (
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"cld\n\t"
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"jmp 0x08:1f\n\t"
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"1: .code16\n\t"
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"mov ax, 0x10\n\t"
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"mov ds, ax\n\t"
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"mov es, ax\n\t"
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"mov fs, ax\n\t"
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"mov gs, ax\n\t"
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"mov ss, ax\n\t"
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"mov eax, cr0\n\t"
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"and al, 0xfe\n\t"
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"mov cr0, eax\n\t"
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"jmp 0x0000:1f\n\t"
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"1:\n\t"
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"mov ax, 0\n\t"
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"mov ds, ax\n\t"
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"mov es, ax\n\t"
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"mov fs, ax\n\t"
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"mov gs, ax\n\t"
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"mov ss, ax\n\t"
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"sti\n\t"
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"push 0\n\t"
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"push 0x7c00\n\t"
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"retf\n\t"
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".code32\n\t"
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:
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: "d" (drive)
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: "memory"
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);
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}
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void chainload(char *config) {
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uint64_t val;
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int part; {
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char *part_config = config_get_value(config, 0, "PARTITION");
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if (part_config == NULL) {
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part = -1;
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} else {
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val = strtoui(part_config, NULL, 10);
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if (val < 1 || val > 256) {
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panic("BIOS partition number outside range 1-256");
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}
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part = val - 1;
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}
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}
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int drive; {
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char *drive_config = config_get_value(config, 0, "DRIVE");
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if (drive_config == NULL) {
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panic("DRIVE not specified");
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}
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val = strtoui(drive_config, NULL, 10);
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if (val < 1 || val > 16) {
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panic("BIOS drive number outside range 1-16");
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}
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drive = (val - 1) + 0x80;
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}
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term_deinit();
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if (part != -1) {
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struct part p;
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part_get(&p, drive, part);
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part_read(&p, (void *)0x7c00, 0, 512);
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} else {
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disk_read(drive, (void *)0x7c00, 0, 512);
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}
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mtrr_restore();
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spinup(drive);
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}
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