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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL )
#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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