/* At entry, the processor is in 16 bit real mode and the code is being
* executed from an address it was not linked to. Code must be pic and
* 32 bit sensitive until things are fixed up.
*
* Also be very careful as the stack is at the rear end of the interrupt
* table so using a noticeable amount of stack space is a no-no.
*/
#define PNP_SIGNATURE ( '$' + ( 'P' << 8 ) + ( 'n' << 16 ) + ( 'P' << 24 ) )
#define PMM_SIGNATURE ( '$' + ( 'P' << 8 ) + ( 'M' << 16 ) + ( 'M' << 24 ) )
#define STACK_MAGIC ( 'L' + ( 'R' << 8 ) + ( 'E' << 16 ) + ( 'T' << 24 ) )
#define PNP_GET_BBS_VERSION 0x60
.text
.code16
.arch i386
.section ".prefix", "ax", @progbits
.org 0x00
romheader:
.word 0xAA55 /* BIOS extension signature */
romheader_size: .byte _load_size_sect /* Size in 512-byte blocks */
jmp init /* Initialisation vector */
checksum:
.byte 0
.org 0x16
.word undiheader
.org 0x18
.word pciheader
.org 0x1a
.word pnpheader
.size romheader, . - romheader
.section ".zinfo.fixup", "a" /* Compressor fixup information */
.ascii "SUBB"
.long romheader_size
.long 512
.long 0
.previous
pciheader:
.ascii "PCIR" /* Signature */
.word pci_vendor_id /* Vendor ID */
.word pci_device_id /* Device ID */
.word 0x0000 /* pointer to vital product data */
.word pciheader_len /* PCI data structure length */
.byte 0x00 /* PCI data structure revision */
.byte 0x02 /* Device Base Type code */
.byte 0x00 /* Device Sub-Type code */
.byte 0x00 /* Device Interface Type code */
pciheader_size: .word _load_size_sect /* Image length same as offset 02h */
.word 0x0001 /* revision level of code/data */
.byte 0x00 /* code type */
.byte 0x80 /* Flags (last PCI data structure) */
.word 0x0000 /* reserved */
.equ pciheader_len, . - pciheader
.size pciheader, . - pciheader
.section ".zinfo.fixup", "a" /* Compressor fixup information */
.ascii "SUBW"
.long pciheader_size
.long 512
.long 0
.previous
pnpheader:
.ascii "$PnP" /* Signature */
.byte 0x01 /* Structure revision */
.byte ( pnpheader_len / 16 ) /* Length (in 16 byte increments) */
.word 0x0000 /* Offset of next header */
.byte 0x00 /* Reserved */
.byte 0x00 /* Checksum */
.long 0x00000000 /* Device identifier */
.word mfgstr /* Manufacturer string */
.word prodstr /* Product name */
.byte 0x02 /* Device base type code */
.byte 0x00 /* Device sub-type code */
.byte 0x00 /* Device interface type code */
.byte 0x54 /* Device indicator */
.word 0x0000 /* Boot connection vector */
.word 0x0000 /* Disconnect vector */
.word bev_entry /* Boot execution vector */
.word 0x0000 /* Reserved */
.word 0x0000 /* Static resource information vector*/
.equ pnpheader_len, . - pnpheader
.size pnpheader, . - pnpheader
mfgstr:
.asciz "http://etherboot.org"
.size mfgstr, . - mfgstr
prodstr:
.asciz "gPXE"
.size prodstr, . - prodstr
undiheader:
.ascii "UNDI" /* Signature */
.byte undiheader_len /* Length of structure */
.byte 0 /* Checksum */
.byte 0 /* Structure revision */
.byte 0,1,2 /* PXE version: 2.1.0 */
.word undiloader /* Offset to loader routine */
.word _data16_size /* Stack segment size */
.word _data16_size /* Data segment size */
.word _text16_size /* Code segment size */
.equ undiheader_len, . - undiheader
.size undiheader, . - undiheader
/* Initialisation (called once during POST)
*
* Determine whether or not this is a PnP system via a signature
* check. If it is PnP, return to the PnP BIOS indicating that we are
* a boot-capable device; the BIOS will call our boot execution vector
* if it wants to boot us. If it is not PnP, hook INT 19.
*/
init:
/* Preserve registers, clear direction flag, set %ds=%cs */
pushaw
pushw %ds
pushw %es
cld
pushw %cs
popw %ds
/* Print message as early as possible */
movw $init_message, %si
call print_message
/* Check for PnP BIOS */
testw $0x0f, %di /* PnP signature must be aligned - bochs */
jnz hook_int19 /* uses unalignment to indicate 'fake' PnP. */
cmpl $PNP_SIGNATURE, %es:0(%di)
jne hook_int19
/* Is PnP: print PnP message */
movw $init_message_pnp, %si
call print_message
xchgw %bx, %bx
/* Check for BBS */
pushw %es:0x1b(%di) /* Real-mode data segment */
pushw %ds /* &(bbs_version) */
pushw $bbs_version
pushw $PNP_GET_BBS_VERSION
lcall *%es:0xd(%di)
addw $8, %sp
testw %ax, %ax
jne hook_int19
movw $init_message_bbs, %si
call print_message
jmp hook_bbs
/* Not BBS-compliant - must hook INT 19 */
hook_int19:
movw $init_message_int19, %si
call print_message
xorw %ax, %ax
movw %ax, %es
pushw %cs
pushw $int19_entry
popl %es:( 0x19 * 4 )
hook_bbs:
/* Check for PMM */
movw $( 0xe000 - 1 ), %di
pmm_scan:
incw %di
jz no_pmm
movw %di, %es
cmpl $PMM_SIGNATURE, %es:0
jne pmm_scan
xorw %bx, %bx
xorw %si, %si
movzbw %es:5, %cx
1: es lodsb
addb %al, %bl
loop 1b
jnz pmm_scan
/* PMM found: print PMM message */
movw $init_message_pmm, %si
call print_message
/* Try to allocate 2MB block via PMM */
pushw $0x0006 /* Aligned, extended memory */
pushl $0xffffffff /* No handle */
pushl $( 0x00200000 / 16 ) /* 2MB in paragraphs */
pushw $0x0000 /* pmmAllocate */
lcall *%es:7
addw $12, %sp
testw %dx, %dx /* %ax==0 even on success, since align=2MB */
jnz gotpmm
movw $init_message_pmm_failed, %si
call print_message
jmp no_pmm
gotpmm: /* PMM allocation succeeded: copy ROM to PMM block */
pushal /* PMM presence implies 1kB stack */
movw %ax, %es /* %ax=0 already - see above */
pushw %dx
pushw %ax
popl %edi
movl %edi, image_source
xorl %esi, %esi
movzbl romheader_size, %ecx
shll $9, %ecx
addr32 rep movsb /* PMM presence implies flat real mode */
movl %edi, decompress_to
/* Shrink ROM and update checksum */
xorw %bx, %bx
xorw %si, %si
movw $_prefix_size_sect, %cx
movb %cl, romheader_size
shlw $9, %cx
1: lodsb
addb %al, %bl
loop 1b
subb %bl, checksum
popal
no_pmm:
/* Print CRLF to terminate messages */
movw $'\n', %ax
call print_character
/* Restore registers */
popw %es
popw %ds
popaw
/* Indicate boot capability to PnP BIOS, if present */
movw $0x20, %ax
lret
.size init, . - init
init_message:
.asciz "gPXE (http://etherboot.org) -"
.size init_message, . - init_message
init_message_pnp:
.asciz " PnP"
.size init_message_pnp, . - init_message_pnp
init_message_bbs:
.asciz " BBS"
.size init_message_bbs, . - init_message_bbs
init_message_pmm:
.asciz " PMM"
.size init_message_pmm, . - init_message_pmm
init_message_pmm_failed:
.asciz "(failed)"
.size init_message_pmm_failed, . - init_message_pmm_failed
init_message_int19:
.asciz " INT19"
.size init_message_int19, . - init_message_int19
/* ROM image location
*
* May be either within option ROM space, or within PMM-allocated block.
*/
image_source:
.long 0
.size image_source, . - image_source
/* Temporary decompression area
*
* May be either at HIGHMEM_LOADPOINT, or within PMM-allocated block.
*/
decompress_to:
.long HIGHMEM_LOADPOINT
.size decompress_to, . - decompress_to
/* BBS version
*
* Filled in by BBS BIOS. We ignore the value.
*/
bbs_version:
.word 0
/* Boot Execution Vector entry point
*
* Called by the PnP BIOS when it wants to boot us.
*/
bev_entry:
pushw %cs
call exec
lret
.size bev_entry, . - bev_entry
/* INT19 entry point
*
* Called via the hooked INT 19 if we detected a non-PnP BIOS.
*/
int19_entry:
pushw %cs
call exec
/* No real way to return from INT19 */
int $0x18
.size int19_entry, . - int19_entry
/* Execute as a boot device
*
*/
exec: /* Set %ds = %cs */
pushw %cs
popw %ds
/* Print message as soon as possible */
movw $exec_message, %si
call print_message
/* Store magic word on BIOS stack and remember BIOS %ss:sp */
pushl $STACK_MAGIC
movw %ss, %dx
movw %sp, %bp
/* Obtain a reasonably-sized temporary stack */
xorw %ax, %ax
movw %ax, %ss
movw $0x7c00, %sp
/* Install gPXE */
movl image_source, %esi
movl decompress_to, %edi
call alloc_basemem
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: /* Call main() */
pushl $main
pushw %cs
call prot_call
/* No need to clean up stack; we are about to reload %ss:sp */
/* Restore BIOS stack */
movw %dx, %ss
movw %bp, %sp
/* Check magic word on BIOS stack */
popl %eax
cmpl $STACK_MAGIC, %eax
jne 1f
/* BIOS stack OK: return to caller */
lret
1: /* BIOS stack corrupt: use INT 18 */
int $0x18
.previous
exec_message:
.asciz "gPXE starting boot\n"
.size exec_message, . - exec_message
/* UNDI loader
*
* Called by an external program to load our PXE stack.
*/
undiloader:
/* Save registers */
pushl %esi
pushl %edi
pushw %es
pushw %bx
/* UNDI loader parameter structure address into %es:%di */
movw %sp, %bx
movw %ss:12(%bx), %di
movw %ss:14(%bx), %es
/* Install to specified real-mode addresses */
pushw %di
movw %es:12(%di), %bx
movw %es:14(%di), %ax
movl %cs:image_source, %esi
movl %cs:decompress_to, %edi
call install_prealloc
popw %di
/* Call UNDI loader C code */
pushl $pxe_loader_call
pushw %cs
pushw $1f
pushw %ax
pushw $prot_call
lret
1: popw %bx /* discard */
popw %bx /* discard */
/* Restore registers and return */
popw %bx
popw %es
popl %edi
popl %esi
lret
.size undiloader, . - undiloader
