-/*
- Copyright (C) 2000, Entity Cyber, Inc.
-
- Authors: Gary Byers (gb@thinguin.org)
- Marty Connor (mdc@thinguin.org)
-
- This software may be used and distributed according to the terms
- of the GNU Public License (GPL), incorporated herein by reference.
-
- Description:
-
- This is just a little bit of code and data that can get prepended
- to a ROM image in order to allow bootloaders to load the result
- as if it were a Linux kernel image.
-
- A real Linux kernel image consists of a one-sector boot loader
- (to load the image from a floppy disk), followed a few sectors
- of setup code, followed by the kernel code itself. There's
- a table in the first sector (starting at offset 497) that indicates
- how many sectors of setup code follow the first sector and which
- contains some other parameters that aren't interesting in this
- case.
-
- When a bootloader loads the sectors that comprise a kernel image,
- it doesn't execute the code in the first sector (since that code
- would try to load the image from a floppy disk.) The code in the
- first sector below doesn't expect to get executed (and prints an
- error message if it ever -is- executed.)
-
- We don't require much in the way of setup code. Historically, the
- Linux kernel required at least 4 sectors of setup code.
- Therefore, at least 4 sectors must be present even though we don't
- use them.
-
-*/
-
FILE_LICENCE ( GPL_ANY )
-#define SETUPSECS 4 /* Minimal nr of setup-sectors */
-#define PREFIXSIZE ((SETUPSECS+1)*512)
-#define PREFIXPGH (PREFIXSIZE / 16 )
-#define BOOTSEG 0x07C0 /* original address of boot-sector */
-#define INITSEG 0x9000 /* we move boot here - out of the way */
-#define SETUPSEG 0x9020 /* setup starts here */
-#define SYSSEG 0x1000 /* system loaded at 0x10000 (65536). */
+#define BZI_RM_SEGMENT 0x1000
+#define BZI_LOAD_HIGH_ADDR 0x100000
.text
- .code16
.arch i386
- .org 0
+ .code16
.section ".prefix", "ax", @progbits
.globl _lkrn_start
_lkrn_start:
-/*
- This is a minimal boot sector. If anyone tries to execute it (e.g., if
- a .lilo file is dd'ed to a floppy), print an error message.
-*/
-
-bootsector:
- jmp $BOOTSEG, $1f /* reload cs:ip to match relocation addr */
-1:
- movw $0x2000, %di /* 0x2000 is arbitrary value >= length
- of bootsect + room for stack */
-
- movw $BOOTSEG, %ax
- movw %ax,%ds
- movw %ax,%es
-
- cli
- movw %ax, %ss /* put stack at BOOTSEG:0x2000. */
- movw %di,%sp
- sti
-
- movw $why_end-why, %cx
- movw $why, %si
-
- movw $0x0007, %bx /* page 0, attribute 7 (normal) */
- movb $0x0e, %ah /* write char, tty mode */
-prloop:
- lodsb
- int $0x10
- loop prloop
-freeze: jmp freeze
-
-why: .ascii "This image cannot be loaded from a floppy disk.\r\n"
-why_end:
+/*****************************************************************************
+ *
+ * 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.
+ *
+ */
-/*
- The following header is documented in the Linux source code at
- Documentation/x86/boot.txt
-*/
- .org 497
-setup_sects:
- .byte SETUPSECS
-root_flags:
+ .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 -PREFIXPGH
-
+syssize:
+ .long 0
.section ".zinfo.fixup", "a", @progbits /* Compressor fixups */
- .ascii "ADDL"
+ .ascii "ADPL"
.long syssize
.long 16
.long 0
.previous
-
-ram_size:
+ram_size:
.word 0
-vid_mode:
+vid_mode:
.word 0
-root_dev:
+root_dev:
.word 0
-boot_flag:
- .word 0xAA55
+boot_flag:
+ .word 0xaa55
jump:
/* Manually specify a two-byte jmp instruction here rather
- * than leaving it up to the assembler. */
- .byte 0xeb
- .byte setup_code - header
+ * than leaving it up to the assembler.
+ */
+ .byte 0xeb, ( setup - header )
header:
.byte 'H', 'd', 'r', 'S'
version:
realmode_swtch:
.long 0
start_sys:
- .word 0
+ .word BZI_RM_SEGMENT
kernel_version:
.word version_string - 0x200
type_of_loader:
.byte 0
loadflags:
- .byte 0
+ .byte 0x01 /* LOADED_HIGH */
setup_move_size:
.word 0
code32_start:
.long 0
heap_end_ptr:
.word 0
-pad1:
- .word 0
+ext_loader_ver:
+ .byte 0
+ext_loader_type:
+ .byte 0
cmd_line_ptr:
.long 0
initrd_addr_max:
- /* We don't use an initrd but some bootloaders (e.g. SYSLINUX) have
- * been known to require this field. Set the value to 2 GB. This
- * value is also used by the Linux kernel. */
- .long 0x7fffffff
+ .long 0xffffffff
kernel_alignment:
.long 0
relocatable_kernel:
.byte 0
-pad2:
- .byte 0, 0, 0
+min_alignment:
+ .byte 0
+xloadflags:
+ .word 0
cmdline_size:
.long 0x7ff
hardware_subarch:
version_string:
.asciz VERSION
-/*
- We don't need to do too much setup.
-
- This code gets loaded at SETUPSEG:0. It wants to start
- executing the image that's loaded at SYSSEG:0 and
- whose entry point is SYSSEG:0.
-*/
-setup_code:
- /* We expect to be contiguous in memory once loaded. The Linux image
- * boot process requires that setup code is loaded separately from
- * "non-real code". Since we don't need any information that's left
- * in the prefix, it doesn't matter: we just have to ensure that
- * %cs:0000 is where the start of the image *would* be.
- */
- ljmp $(SYSSEG-(PREFIXSIZE/16)), $run_ipxe
-
-
- .org PREFIXSIZE
-/*
- We're now at the beginning of the kernel proper.
+/*****************************************************************************
+ *
+ * Setup code
+ *
*/
-run_ipxe:
+
+setup:
+ /* Fix up code segment */
+ ljmp $BZI_RM_SEGMENT, $1f
+1:
/* Set up stack just below 0x7c00 and clear direction flag */
xorw %ax, %ax
movw %ax, %ss
cld
/* Retrieve command-line pointer */
- movl %ds:cmd_line_ptr, %edx
+ movl cmd_line_ptr, %edx
testl %edx, %edx
jz no_cmd_line
jnz 1f
orl $0xffffffff, %ebp /* Allow arbitrary relocation if no initrd */
1:
-
/* Install iPXE */
call alloc_basemem
xorl %esi, %esi
/* 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
projects / thirdparty / ipxe.git / commitdiff
