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https://gitlab.com/qemu-project/qemu
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Convert linux bootrom to external rom and fw_cfg
We already have a working multiboot implementation that uses fw_cfg to get its kernel module etc. data in int19 runtime now. So what's missing is a working linux boot option rom. While at it I figured it would be a good idea to take the opcode generator out of pc.c and instead use a proper option rom, like we do with multiboot. So here it is - an fw_cfg using option rom for -kernel with linux! Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Alexander Graf
Anthony Liguori
parent
dd4b2659cd
commit
57a46d0579
5 changed files with 170 additions and 102 deletions
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@ -20,7 +20,13 @@
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#define FW_CFG_KERNEL_ENTRY 0x10
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#define FW_CFG_KERNEL_DATA 0x11
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#define FW_CFG_INITRD_DATA 0x12
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#define FW_CFG_MAX_ENTRY 0x13
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#define FW_CFG_CMDLINE_ADDR 0x13
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#define FW_CFG_CMDLINE_SIZE 0x14
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#define FW_CFG_CMDLINE_DATA 0x15
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#define FW_CFG_SETUP_ADDR 0x16
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#define FW_CFG_SETUP_SIZE 0x17
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#define FW_CFG_SETUP_DATA 0x18
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#define FW_CFG_MAX_ENTRY 0x19
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#define FW_CFG_WRITE_CHANNEL 0x4000
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#define FW_CFG_ARCH_LOCAL 0x8000
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122
hw/pc.c
122
hw/pc.c
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@ -487,85 +487,6 @@ static void *bochs_bios_init(void)
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return fw_cfg;
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}
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/* Generate an initial boot sector which sets state and jump to
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a specified vector */
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static void generate_bootsect(uint32_t gpr[8], uint16_t segs[6], uint16_t ip)
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{
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uint8_t rom[512], *p, *reloc;
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uint8_t sum;
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int i;
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memset(rom, 0, sizeof(rom));
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p = rom;
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/* Make sure we have an option rom signature */
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*p++ = 0x55;
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*p++ = 0xaa;
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/* ROM size in sectors*/
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*p++ = 1;
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/* Hook int19 */
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*p++ = 0x50; /* push ax */
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*p++ = 0x1e; /* push ds */
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*p++ = 0x31; *p++ = 0xc0; /* xor ax, ax */
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*p++ = 0x8e; *p++ = 0xd8; /* mov ax, ds */
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*p++ = 0xc7; *p++ = 0x06; /* movvw _start,0x64 */
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*p++ = 0x64; *p++ = 0x00;
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reloc = p;
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*p++ = 0x00; *p++ = 0x00;
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*p++ = 0x8c; *p++ = 0x0e; /* mov cs,0x66 */
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*p++ = 0x66; *p++ = 0x00;
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*p++ = 0x1f; /* pop ds */
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*p++ = 0x58; /* pop ax */
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*p++ = 0xcb; /* lret */
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/* Actual code */
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*reloc = (p - rom);
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*p++ = 0xfa; /* CLI */
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*p++ = 0xfc; /* CLD */
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for (i = 0; i < 6; i++) {
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if (i == 1) /* Skip CS */
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continue;
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*p++ = 0xb8; /* MOV AX,imm16 */
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*p++ = segs[i];
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*p++ = segs[i] >> 8;
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*p++ = 0x8e; /* MOV <seg>,AX */
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*p++ = 0xc0 + (i << 3);
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}
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for (i = 0; i < 8; i++) {
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*p++ = 0x66; /* 32-bit operand size */
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*p++ = 0xb8 + i; /* MOV <reg>,imm32 */
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*p++ = gpr[i];
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*p++ = gpr[i] >> 8;
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*p++ = gpr[i] >> 16;
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*p++ = gpr[i] >> 24;
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}
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*p++ = 0xea; /* JMP FAR */
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*p++ = ip; /* IP */
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*p++ = ip >> 8;
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*p++ = segs[1]; /* CS */
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*p++ = segs[1] >> 8;
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/* sign rom */
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sum = 0;
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for (i = 0; i < (sizeof(rom) - 1); i++)
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sum += rom[i];
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rom[sizeof(rom) - 1] = -sum;
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rom_add_blob("linux-bootsect", rom, sizeof(rom),
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PC_ROM_MIN_OPTION, PC_ROM_MAX, PC_ROM_ALIGN);
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}
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static long get_file_size(FILE *f)
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{
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long where, size;
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@ -812,12 +733,9 @@ static void load_linux(void *fw_cfg,
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target_phys_addr_t max_ram_size)
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{
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uint16_t protocol;
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uint32_t gpr[8];
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uint16_t seg[6];
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uint16_t real_seg;
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int setup_size, kernel_size, initrd_size = 0, cmdline_size;
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uint32_t initrd_max;
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uint8_t header[8192], *setup, *kernel;
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uint8_t header[8192], *setup, *kernel, *initrd_data;
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target_phys_addr_t real_addr, prot_addr, cmdline_addr, initrd_addr = 0;
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FILE *f;
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char *vmode;
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@ -886,9 +804,11 @@ static void load_linux(void *fw_cfg,
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if (initrd_max >= max_ram_size-ACPI_DATA_SIZE)
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initrd_max = max_ram_size-ACPI_DATA_SIZE-1;
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/* kernel command line */
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rom_add_blob_fixed("cmdline", kernel_cmdline,
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strlen(kernel_cmdline)+1, cmdline_addr);
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fw_cfg_add_i32(fw_cfg, FW_CFG_CMDLINE_ADDR, cmdline_addr);
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fw_cfg_add_i32(fw_cfg, FW_CFG_CMDLINE_SIZE, strlen(kernel_cmdline)+1);
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fw_cfg_add_bytes(fw_cfg, FW_CFG_CMDLINE_DATA,
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(uint8_t*)strdup(kernel_cmdline),
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strlen(kernel_cmdline)+1);
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if (protocol >= 0x202) {
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stl_p(header+0x228, cmdline_addr);
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@ -937,7 +857,13 @@ static void load_linux(void *fw_cfg,
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initrd_size = get_image_size(initrd_filename);
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initrd_addr = (initrd_max-initrd_size) & ~4095;
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rom_add_file_fixed(initrd_filename, initrd_addr);
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initrd_data = qemu_malloc(initrd_size);
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load_image(initrd_filename, initrd_data);
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fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_ADDR, initrd_addr);
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fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_SIZE, initrd_size);
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fw_cfg_add_bytes(fw_cfg, FW_CFG_INITRD_DATA, initrd_data, initrd_size);
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stl_p(header+0x218, initrd_addr);
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stl_p(header+0x21c, initrd_size);
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@ -957,21 +883,17 @@ static void load_linux(void *fw_cfg,
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fread(kernel, 1, kernel_size, f);
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fclose(f);
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memcpy(setup, header, MIN(sizeof(header), setup_size));
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rom_add_blob_fixed("linux-setup", setup,
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setup_size, real_addr);
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rom_add_blob_fixed(kernel_filename, kernel,
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kernel_size, prot_addr);
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qemu_free(setup);
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qemu_free(kernel);
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/* generate bootsector to set up the initial register state */
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real_seg = real_addr >> 4;
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seg[0] = seg[2] = seg[3] = seg[4] = seg[4] = real_seg;
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seg[1] = real_seg+0x20; /* CS */
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memset(gpr, 0, sizeof gpr);
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gpr[4] = cmdline_addr-real_addr-16; /* SP (-16 is paranoia) */
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fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ADDR, prot_addr);
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fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_SIZE, kernel_size);
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fw_cfg_add_bytes(fw_cfg, FW_CFG_KERNEL_DATA, kernel, kernel_size);
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generate_bootsect(gpr, seg, 0);
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fw_cfg_add_i32(fw_cfg, FW_CFG_SETUP_ADDR, real_addr);
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fw_cfg_add_i32(fw_cfg, FW_CFG_SETUP_SIZE, setup_size);
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fw_cfg_add_bytes(fw_cfg, FW_CFG_SETUP_DATA, setup, setup_size);
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option_rom[nb_option_roms] = "linuxboot.bin";
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nb_option_roms++;
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}
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static const int ide_iobase[2] = { 0x1f0, 0x170 };
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BIN
pc-bios/linuxboot.bin
Normal file
BIN
pc-bios/linuxboot.bin
Normal file
Binary file not shown.
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@ -13,7 +13,7 @@ CFLAGS += -I$(SRC_PATH)
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CFLAGS += $(call cc-option, $(CFLAGS), -fno-stack-protector)
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QEMU_CFLAGS = $(CFLAGS)
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build-all: multiboot.bin
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build-all: multiboot.bin linuxboot.bin
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%.img: %.o
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$(call quiet-command,$(LD) -Ttext 0 -e _start -s -o $@ $<," Building $(TARGET_DIR)$@")
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140
pc-bios/optionrom/linuxboot.S
Normal file
140
pc-bios/optionrom/linuxboot.S
Normal file
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@ -0,0 +1,140 @@
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/*
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* Linux Boot Option ROM
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*
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* Copyright Novell Inc, 2009
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* Authors: Alexander Graf <agraf@suse.de>
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*
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* Based on code in hw/pc.c.
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*/
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#include "optionrom.h"
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BOOT_ROM_START
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run_linuxboot:
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cli
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cld
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jmp copy_kernel
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boot_kernel:
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read_fw FW_CFG_SETUP_ADDR
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mov %eax, %ebx
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shr $4, %ebx
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/* All segments contain real_addr */
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mov %bx, %ds
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mov %bx, %es
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mov %bx, %fs
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mov %bx, %gs
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mov %bx, %ss
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/* CX = CS we want to jump to */
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add $0x20, %bx
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mov %bx, %cx
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/* SP = cmdline_addr-real_addr-16 */
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read_fw FW_CFG_CMDLINE_ADDR
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mov %eax, %ebx
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read_fw FW_CFG_SETUP_ADDR
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sub %eax, %ebx
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sub $16, %ebx
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mov %ebx, %esp
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/* Build indirect lret descriptor */
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pushw %cx /* CS */
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xor %ax, %ax
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pushw %ax /* IP = 0 */
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/* Clear registers */
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xor %eax, %eax
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xor %ebx, %ebx
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xor %ecx, %ecx
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xor %edx, %edx
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xor %edi, %edi
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xor %ebp, %ebp
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/* Jump to Linux */
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lret
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copy_kernel:
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/* We need to load the kernel into memory we can't access in 16 bit
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mode, so let's get into 32 bit mode, write the kernel and jump
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back again. */
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/* Set DS to SS+SP - 0x10, so we can write our GDT descriptor there */
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mov %ss, %eax
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shl $4, %eax
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add %esp, %eax
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sub $0x10, %eax
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shr $4, %eax
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/* Now create the GDT descriptor */
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mov %cs, %eax
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shl $4, %eax
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movw $((3 * 8) - 1), %bx
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movw %bx, %gs:0
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movl $gdt, %ebx
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add %eax, %ebx
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movl %ebx, %gs:2
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/* And load the GDT */
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data32 lgdt %gs:0
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/* Get us to protected mode now */
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mov $1, %eax
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mov %eax, %cr0
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/* So we can set DS to a 32-bit segment */
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mov $0x10, %eax
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mov %eax, %ds
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/* We're now running in 16-bit CS, but 32-bit DS! */
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/* Load kernel and initrd */
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read_fw_blob(FW_CFG_KERNEL)
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read_fw_blob(FW_CFG_INITRD)
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read_fw_blob(FW_CFG_CMDLINE)
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read_fw_blob(FW_CFG_SETUP)
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/* And now jump into Linux! */
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mov $0, %eax
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mov %eax, %cr0
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/* DS = CS */
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mov %cs, %ax
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mov %ax, %ds
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jmp boot_kernel
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/* Variables */
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.align 4, 0
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gdt:
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/* 0x00 */
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.byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
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/* 0x08: code segment (base=0, limit=0xfffff, type=32bit code exec/read, DPL=0, 4k) */
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.byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9a, 0xcf, 0x00
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/* 0x10: data segment (base=0, limit=0xfffff, type=32bit data read/write, DPL=0, 4k) */
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.byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0xcf, 0x00
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BOOT_ROM_END
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