--- /dev/null
+/*
+ * Linux Boot Option ROM
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright Novell Inc, 2009
+ * Authors: Alexander Graf <agraf@suse.de>
+ *
+ * Based on code in hw/pc.c.
+ */
+
+#include "optionrom.h"
+
+#define BOOT_ROM_PRODUCT "Linux loader"
+
+BOOT_ROM_START
+
+run_linuxboot:
+
+ cli
+ cld
+
+ jmp copy_kernel
+boot_kernel:
+
+ read_fw FW_CFG_SETUP_ADDR
+
+ mov %eax, %ebx
+ shr $4, %ebx
+
+ /* All segments contain real_addr */
+ mov %bx, %ds
+ mov %bx, %es
+ mov %bx, %fs
+ mov %bx, %gs
+ mov %bx, %ss
+
+ /* CX = CS we want to jump to */
+ add $0x20, %bx
+ mov %bx, %cx
+
+ /* SP = cmdline_addr-real_addr-16 */
+ read_fw FW_CFG_CMDLINE_ADDR
+ mov %eax, %ebx
+ read_fw FW_CFG_SETUP_ADDR
+ sub %eax, %ebx
+ sub $16, %ebx
+ mov %ebx, %esp
+
+ /* Build indirect lret descriptor */
+ pushw %cx /* CS */
+ xor %ax, %ax
+ pushw %ax /* IP = 0 */
+
+ /* Clear registers */
+ xor %eax, %eax
+ xor %ebx, %ebx
+ xor %ecx, %ecx
+ xor %edx, %edx
+ xor %edi, %edi
+ xor %ebp, %ebp
+
+ /* Jump to Linux */
+ lret
+
+
+copy_kernel:
+ /* Read info block in low memory (0x10000 or 0x90000) */
+ read_fw FW_CFG_SETUP_ADDR
+ shr $4, %eax
+ mov %eax, %es
+ xor %edi, %edi
+ read_fw_blob_addr32_edi(FW_CFG_SETUP)
+
+ cmpw $0x203, %es:0x206 // if protocol >= 0x203
+ jae 1f // have initrd_max
+ movl $0x37ffffff, %es:0x22c // else assume 0x37ffffff
+1:
+
+ /* Check if using kernel-specified initrd address */
+ read_fw FW_CFG_INITRD_ADDR
+ mov %eax, %edi // (load_kernel wants it in %edi)
+ read_fw FW_CFG_INITRD_SIZE // find end of initrd
+ add %edi, %eax
+ xor %es:0x22c, %eax // if it matches es:0x22c
+ and $-4096, %eax // (apart from padding for page)
+ jz load_kernel // then initrd is not at top
+ // of memory
+
+ /* pc.c placed the initrd at end of memory. Compute a better
+ * initrd address based on e801 data.
+ */
+ mov $0xe801, %ax
+ xor %cx, %cx
+ xor %dx, %dx
+ int $0x15
+
+ /* Output could be in AX/BX or CX/DX */
+ or %cx, %cx
+ jnz 1f
+ or %dx, %dx
+ jnz 1f
+ mov %ax, %cx
+ mov %bx, %dx
+1:
+
+ or %dx, %dx
+ jnz 2f
+ addw $1024, %cx /* add 1 MB */
+ movzwl %cx, %edi
+ shll $10, %edi /* convert to bytes */
+ jmp 3f
+
+2:
+ addw $16777216 >> 16, %dx /* add 16 MB */
+ movzwl %dx, %edi
+ shll $16, %edi /* convert to bytes */
+
+3:
+ read_fw FW_CFG_INITRD_SIZE
+ subl %eax, %edi
+ andl $-4096, %edi /* EDI = start of initrd */
+ movl %edi, %es:0x218 /* put it in the header */
+
+load_kernel:
+ /* We need to load the kernel into memory we can't access in 16 bit
+ mode, so let's get into 32 bit mode, write the kernel and jump
+ back again. */
+
+ /* Reserve space on the stack for our GDT descriptor. */
+ mov %esp, %ebp
+ sub $16, %esp
+
+ /* Now create the GDT descriptor */
+ movw $((3 * 8) - 1), -16(%bp)
+ mov %cs, %eax
+ movzwl %ax, %eax
+ shl $4, %eax
+ addl $gdt, %eax
+ movl %eax, -14(%bp)
+
+ /* And load the GDT */
+ data32 lgdt -16(%bp)
+ mov %ebp, %esp
+
+ /* Get us to protected mode now */
+ mov $1, %eax
+ mov %eax, %cr0
+
+ /* So we can set ES to a 32-bit segment */
+ mov $0x10, %eax
+ mov %eax, %es
+
+ /* We're now running in 16-bit CS, but 32-bit ES! */
+
+ /* Load kernel and initrd */
+ read_fw_blob_addr32_edi(FW_CFG_INITRD)
+ read_fw_blob_addr32(FW_CFG_KERNEL)
+ read_fw_blob_addr32(FW_CFG_CMDLINE)
+
+ /* And now jump into Linux! */
+ mov $0, %eax
+ mov %eax, %cr0
+
+ /* ES = CS */
+ mov %cs, %ax
+ mov %ax, %es
+
+ jmp boot_kernel
+
+/* Variables */
+
+.align 4, 0
+gdt:
+ /* 0x00 */
+.byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+
+ /* 0x08: code segment (base=0, limit=0xfffff, type=32bit code exec/read, DPL=0, 4k) */
+.byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9a, 0xcf, 0x00
+
+ /* 0x10: data segment (base=0, limit=0xfffff, type=32bit data read/write, DPL=0, 4k) */
+.byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0xcf, 0x00
+
+BOOT_ROM_END
Code Review / kvmfornfv.git / blobdiff