--- /dev/null
+FILE_LICENCE ( GPL_ANY )
+
+#define BZI_LOAD_HIGH_ADDR 0x100000
+
+ .text
+ .arch i386
+ .code16
+ .section ".prefix", "ax", @progbits
+ .globl _lkrn_start
+_lkrn_start:
+
+/*****************************************************************************
+ *
+ * Kernel header
+ *
+ * We place our prefix (i.e. our .prefix and .text16.early sections)
+ * within the bzImage real-mode portion which gets loaded at
+ * 1000:0000, and our payload (i.e. everything else) within the
+ * bzImage protected-mode portion which gets loaded at 0x100000
+ * upwards.
+ *
+ */
+
+ .org 0x1f1
+setup_sects:
+ .byte -1 /* Allow for initial "boot sector" */
+ .section ".zinfo.fixup", "a", @progbits /* Compressor fixups */
+ .ascii "ADHL"
+ .long setup_sects
+ .long 512
+ .long 0
+ .previous
+root_flags:
+ .word 0
+syssize:
+ .long 0
+ .section ".zinfo.fixup", "a", @progbits /* Compressor fixups */
+ .ascii "ADPL"
+ .long syssize
+ .long 16
+ .long 0
+ .previous
+ram_size:
+ .word 0
+vid_mode:
+ .word 0
+root_dev:
+ .word 0
+boot_flag:
+ .word 0xaa55
+jump:
+ /* Manually specify a two-byte jmp instruction here rather
+ * than leaving it up to the assembler.
+ */
+ .byte 0xeb, ( setup - header )
+header:
+ .byte 'H', 'd', 'r', 'S'
+version:
+ .word 0x0207 /* 2.07 */
+realmode_swtch:
+ .long 0
+start_sys:
+ .word 0
+kernel_version:
+ .word version_string - 0x200
+type_of_loader:
+ .byte 0
+loadflags:
+ .byte 0x01 /* LOADED_HIGH */
+setup_move_size:
+ .word 0
+code32_start:
+ .long 0
+ramdisk_image:
+ .long 0
+ramdisk_size:
+ .long 0
+bootsect_kludge:
+ .long 0
+heap_end_ptr:
+ .word 0
+ext_loader_ver:
+ .byte 0
+ext_loader_type:
+ .byte 0
+cmd_line_ptr:
+ .long 0
+initrd_addr_max:
+ .long 0xffffffff
+kernel_alignment:
+ .long 0
+relocatable_kernel:
+ .byte 0
+min_alignment:
+ .byte 0
+xloadflags:
+ .word 0
+cmdline_size:
+ .long 0x7ff
+hardware_subarch:
+ .long 0
+hardware_subarch_data:
+ .byte 0, 0, 0, 0, 0, 0, 0, 0
+
+version_string:
+ .asciz VERSION
+
+/*****************************************************************************
+ *
+ * Setup code
+ *
+ */
+
+setup:
+ /* Fix up code segment */
+ pushw %ds
+ pushw $1f
+ lret
+1:
+ /* Set up stack just below 0x7c00 and clear direction flag */
+ xorw %ax, %ax
+ movw %ax, %ss
+ movw $0x7c00, %sp
+ cld
+
+ /* Retrieve command-line pointer */
+ movl cmd_line_ptr, %edx
+ testl %edx, %edx
+ jz no_cmd_line
+
+ /* Set up %es:%di to point to command line */
+ movl %edx, %edi
+ andl $0xf, %edi
+ rorl $4, %edx
+ movw %dx, %es
+
+ /* Find length of command line */
+ pushw %di
+ movw $0xffff, %cx
+ repnz scasb
+ notw %cx
+ popw %si
+
+ /* Make space for command line on stack */
+ movw %sp, %di
+ subw %cx, %di
+ andw $~0xf, %di
+ movw %di, %sp
+
+ /* Copy command line to stack */
+ pushw %ds
+ pushw %es
+ popw %ds
+ pushw %ss
+ popw %es
+ rep movsb
+ popw %ds
+
+ /* Store new command-line pointer */
+ movzwl %sp, %edx
+no_cmd_line:
+
+ /* Calculate maximum relocation address */
+ movl ramdisk_image, %ebp
+ testl %ebp, %ebp
+ jnz 1f
+ orl $0xffffffff, %ebp /* Allow arbitrary relocation if no initrd */
+1:
+ /* Install iPXE */
+ call alloc_basemem
+ xorl %esi, %esi
+ xorl %edi, %edi
+ call install_prealloc
+
+ /* Set up real-mode stack */
+ movw %bx, %ss
+ movw $_estack16, %sp
+
+ /* Jump to .text16 segment */
+ pushw %ax
+ pushw $1f
+ lret
+ .section ".text16", "awx", @progbits
+1:
+ /* Retrieve initrd pointer and size */
+ movl ramdisk_image, %ebp
+ movl ramdisk_size, %ecx
+
+ /* Set up %ds for access to .data16 */
+ movw %bx, %ds
+
+ /* Store command-line pointer */
+ movl %edx, cmdline_phys
+
+ /* Store initrd pointer and size */
+ movl %ebp, initrd_phys
+ movl %ecx, initrd_len
+
+ /* Run iPXE */
+ pushl $main
+ pushw %cs
+ call prot_call
+ popl %ecx /* discard */
+
+ /* Uninstall iPXE */
+ call uninstall
+
+ /* Boot next device */
+ int $0x18
+
+/*****************************************************************************
+ *
+ * Open payload (called by libprefix)
+ *
+ * Parameters:
+ * %ds:0000 : Prefix
+ * %esi : Buffer for copy of image source (or zero if no buffer available)
+ * %ecx : Expected offset within buffer of first payload block
+ * Returns:
+ * %esi : Valid image source address (buffered or unbuffered)
+ * %ecx : Actual offset within buffer of first payload block
+ * CF set on error
+ */
+
+ .section ".text16.early", "awx", @progbits
+ .globl open_payload
+open_payload:
+
+ /* Our payload will always end up at BZI_LOAD_HIGH_ADDR */
+ movl $BZI_LOAD_HIGH_ADDR, %esi
+ xorl %ecx, %ecx
+ lret
+
+ /* Payload must be aligned to a whole number of setup sectors */
+ .globl _payload_align
+ .equ _payload_align, 512
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