#define PXENV_UNDI_SHUTDOWN 0x0005
#define PXENV_UNDI_GET_NIC_TYPE 0x0012
#define PXENV_STOP_UNDI 0x0015
#define PXENV_UNLOAD_STACK 0x0070
.text
.arch i386
.org 0
.code16
#include <undi.h>
#define STACK_MAGIC ( 'L' + ( 'R' << 8 ) + ( 'E' << 16 ) + ( 'T' << 24 ) )
/*****************************************************************************
* Entry point: set operating context, print welcome message
*****************************************************************************
*/
.section ".prefix", "ax", @progbits
jmp $0x7c0, $1f
1:
/* Preserve registers for possible return to PXE */
pushfl
pushal
pushw %gs
pushw %fs
pushw %es
pushw %ds
/* Store magic word on PXE stack and remember PXE %ss:esp */
pushl $STACK_MAGIC
movw %ss, %cs:pxe_ss
movl %esp, %cs:pxe_esp
movw %sp, %bp
movl (10*4+4*2+4)(%bp),%ebp /* !PXE address */
/* Set up %ds */
movw %cs, %ax
movw %ax, %ds
/* Record PXENV+ and !PXE nominal addresses */
movw %es, pxenv_segment /* PXENV+ address */
movw %bx, pxenv_offset
movl %ebp, ppxe_segoff /* !PXE address */
/* Set up %es and %fs */
movw %ax, %es
movw $0x40, %ax /* BIOS data segment access */
movw %ax, %fs
/* Set up stack just below 0x7c00 */
xorw %ax, %ax
movw %ax, %ss
movl $0x7c00, %esp
/* Clear direction flag, for the sake of sanity */
cld
/* Print welcome message */
movw $10f, %si
xorw %di, %di
call print_message
.section ".prefix.data", "aw", @progbits
10: .asciz "PXE->EB:"
.previous
/*****************************************************************************
* Verify PXENV+ structure and record parameters of interest
*****************************************************************************
*/
detect_pxenv:
/* Signature check */
les pxenv_segoff, %bx
cmpl $0x4e455850, %es:(%bx) /* 'PXEN' signature */
jne no_pxenv
cmpw $0x2b56, %es:4(%bx) /* 'V+' signature */
jne no_pxenv
/* Record entry point and UNDI segments */
pushl %es:0x0a(%bx) /* Entry point */
popl entry_segoff
pushw %es:0x24(%bx) /* UNDI code segment */
pushw %es:0x26(%bx) /* UNDI code size */
popl undi_code_segoff
pushw %es:0x20(%bx) /* UNDI data segment */
pushw %es:0x22(%bx) /* UNDI data size */
popl undi_data_segoff
/* Print "PXENV+ at <address>" */
movw $10f, %si
call print_message
call print_segoff
movb $( ',' ), %al
call print_character
jmp 99f
.section ".prefix.data", "aw", @progbits
10: .asciz " PXENV+ at "
.previous
no_pxenv:
xorl %eax, %eax
movl %eax, pxenv_segoff
99:
/*****************************************************************************
* Verify !PXE structure and record parameters of interest
*****************************************************************************
*/
detect_ppxe:
/* Signature check */
les ppxe_segoff, %bx
cmpl $0x45585021, %es:(%bx) /* '!PXE' signature */
jne no_ppxe
/* Record structure address, entry point, and UNDI segments */
pushw %es
popw ppxe_segment
movw %bx, ppxe_offset
pushl %es:0x10(%bx) /* Entry point */
popl entry_segoff
pushw %es:0x30(%bx) /* UNDI code segment */
pushw %es:0x36(%bx) /* UNDI code size */
popl undi_code_segoff
pushw %es:0x28(%bx) /* UNDI data segment */
pushw %es:0x2e(%bx) /* UNDI data size */
popl undi_data_segoff
/* Print "!PXE at <address>" */
movw $10f, %si
call print_message
call print_segoff
movb $( ',' ), %al
call print_character
jmp 99f
.section ".prefix.data", "aw", @progbits
10: .asciz " !PXE at "
.previous
no_ppxe:
xorl %eax, %eax
movl %eax, ppxe_segoff
99:
/*****************************************************************************
* Sanity check: we must have an entry point
*****************************************************************************
*/
check_have_stack:
/* Check for entry point */
movl entry_segoff, %eax
testl %eax, %eax
jnz 99f
/* No entry point: print message and skip everything else */
movw $10f, %si
call print_message
jmp finished
.section ".prefix.data", "aw", @progbits
10: .asciz " No PXE stack found!\n"
.previous
99:
/*****************************************************************************
* Calculate base memory usage by UNDI
*****************************************************************************
*/
find_undi_basemem_usage:
movw undi_code_segment, %ax
movw undi_code_size, %bx
movw undi_data_segment, %cx
movw undi_data_size, %dx
cmpw %ax, %cx
ja 1f
xchgw %ax, %cx
xchgw %bx, %dx
1: /* %ax:%bx now describes the lower region, %cx:%dx the higher */
shrw $6, %ax /* Round down to nearest kB */
movw %ax, undi_fbms_start
addw $0x0f, %dx /* Round up to next segment */
shrw $4, %dx
addw %dx, %cx
addw $((1024 / 16) - 1), %cx /* Round up to next kB */
shrw $6, %cx
movw %cx, undi_fbms_end
/*****************************************************************************
* Print information about detected PXE stack
*****************************************************************************
*/
print_structure_information:
/* Print entry point */
movw $10f, %si
call print_message
les entry_segoff, %bx
call print_segoff
.section ".prefix.data", "aw", @progbits
10: .asciz " entry point at "
.previous
/* Print UNDI code segment */
movw $10f, %si
call print_message
les undi_code_segoff, %bx
call print_segoff
.section ".prefix.data", "aw", @progbits
10: .asciz "\n UNDI code segment "
.previous
/* Print UNDI data segment */
movw $10f, %si
call print_message
les undi_data_segoff, %bx
call print_segoff
.section ".prefix.data", "aw", @progbits
10: .asciz ", data segment "
.previous
/* Print UNDI memory usage */
movw $10f, %si
call print_message
movw undi_fbms_start, %ax
call print_word
movb $( '-' ), %al
call print_character
movw undi_fbms_end, %ax
call print_word
movw $20f, %si
call print_message
.section ".prefix.data", "aw", @progbits
10: .asciz " ("
20: .asciz "kB)\n"
.previous
/*****************************************************************************
* Determine physical device
*****************************************************************************
*/
get_physical_device:
/* Issue PXENV_UNDI_GET_NIC_TYPE */
movw $PXENV_UNDI_GET_NIC_TYPE, %bx
call pxe_call
jnc 1f
call print_pxe_error
jmp no_physical_device
1: /* Determine physical device type */
movb ( pxe_parameter_structure + 0x02 ), %al
cmpb $2, %al
je pci_physical_device
jmp no_physical_device
pci_physical_device:
/* Record PCI bus:dev.fn and vendor/device IDs */
movl ( pxe_parameter_structure + 0x03 ), %eax
movl %eax, pci_vendor
movw ( pxe_parameter_structure + 0x0b ), %ax
movw %ax, pci_busdevfn
movw $10f, %si
call print_message
call print_pci_busdevfn
movb $0x0a, %al
call print_character
jmp 99f
.section ".prefix.data", "aw", @progbits
10: .asciz " UNDI device is PCI "
.previous
no_physical_device:
/* No device found, or device type not understood */
movw $10f, %si
call print_message
.section ".prefix.data", "aw", @progbits
10: .asciz " Unable to determine UNDI physical device\n"
.previous
99:
/*****************************************************************************
* Leave NIC in a safe state
*****************************************************************************
*/
#ifndef PXELOADER_KEEP_PXE
shutdown_nic:
/* Issue PXENV_UNDI_SHUTDOWN */
movw $PXENV_UNDI_SHUTDOWN, %bx
call pxe_call
jnc 1f
call print_pxe_error
1:
unload_base_code:
/* Issue PXENV_UNLOAD_STACK */
movw $PXENV_UNLOAD_STACK, %bx
call pxe_call
jnc 1f
call print_pxe_error
jmp 99f
1: /* Free base memory used by PXE base code */
movw undi_fbms_start, %ax
movw %fs:(0x13), %bx
call free_basemem
99:
andw $~( UNDI_FL_INITIALIZED | UNDI_FL_KEEP_ALL ), flags
#endif /* PXELOADER_KEEP_PXE */
/*****************************************************************************
* Unload UNDI driver
*****************************************************************************
*/
#ifndef PXELOADER_KEEP_UNDI
unload_undi:
/* Issue PXENV_STOP_UNDI */
movw $PXENV_STOP_UNDI, %bx
call pxe_call
jnc 1f
call print_pxe_error
jmp 99f
1: /* Free base memory used by UNDI */
movw undi_fbms_end, %ax
movw undi_fbms_start, %bx
call free_basemem
/* Clear UNDI_FL_STARTED */
andw $~UNDI_FL_STARTED, flags
99:
#endif /* PXELOADER_KEEP_UNDI */
/*****************************************************************************
* Print remaining free base memory
*****************************************************************************
*/
print_free_basemem:
movw $10f, %si
call print_message
movw %fs:(0x13), %ax
call print_word
movw $20f, %si
call print_message
.section ".prefix.data", "aw", @progbits
10: .asciz " "
20: .asciz "kB free base memory after PXE unload\n"
.previous
/*****************************************************************************
* Exit point
*****************************************************************************
*/
finished:
jmp run_gpxe
/*****************************************************************************
* Subroutine: print segment:offset address
*
* Parameters:
* %es:%bx : segment:offset address to print
* %ds:di : output buffer (or %di=0 to print to console)
* Returns:
* %ds:di : next character in output buffer (if applicable)
*****************************************************************************
*/
print_segoff:
/* Preserve registers */
pushw %ax
/* Print "<segment>:offset" */
movw %es, %ax
call print_hex_word
movb $( ':' ), %al
call print_character
movw %bx, %ax
call print_hex_word
/* Restore registers and return */
popw %ax
ret
/*****************************************************************************
* Subroutine: print decimal word
*
* Parameters:
* %ax : word to print
* %ds:di : output buffer (or %di=0 to print to console)
* Returns:
* %ds:di : next character in output buffer (if applicable)
*****************************************************************************
*/
print_word:
/* Preserve registers */
pushw %ax
pushw %bx
pushw %cx
pushw %dx
/* Build up digit sequence on stack */
movw $10, %bx
xorw %cx, %cx
1: xorw %dx, %dx
divw %bx, %ax
pushw %dx
incw %cx
testw %ax, %ax
jnz 1b
/* Print digit sequence */
1: popw %ax
call print_hex_nibble
loop 1b
/* Restore registers and return */
popw %dx
popw %cx
popw %bx
popw %ax
ret
/*****************************************************************************
* Subroutine: zero 1kB block of base memory
*
* Parameters:
* %bx : block to zero (in kB)
* Returns:
* Nothing
*****************************************************************************
*/
zero_kb:
/* Preserve registers */
pushw %ax
pushw %cx
pushw %di
pushw %es
/* Zero block */
movw %bx, %ax
shlw $6, %ax
movw %ax, %es
movw $0x400, %cx
xorw %di, %di
xorw %ax, %ax
rep stosb
/* Restore registers and return */
popw %es
popw %di
popw %cx
popw %ax
ret
/*****************************************************************************
* Subroutine: free and zero base memory
*
* Parameters:
* %ax : Desired new free base memory counter (in kB)
* %bx : Expected current free base memory counter (in kB)
* %fs : BIOS data segment (0x40)
* Returns:
* None
*
* The base memory from %bx kB to %ax kB is unconditionally zeroed.
* It will be freed if and only if the expected current free base
* memory counter (%bx) matches the actual current free base memory
* counter in 0x40:0x13; if this does not match then the memory will
* be leaked.
*****************************************************************************
*/
free_basemem:
/* Zero base memory */
pushw %bx
1: cmpw %bx, %ax
je 2f
call zero_kb
incw %bx
jmp 1b
2: popw %bx
/* Free base memory */
cmpw %fs:(0x13), %bx /* Update FBMS only if "old" value */
jne 1f /* is correct */
1: movw %ax, %fs:(0x13)
ret
/*****************************************************************************
* Subroutine: make a PXE API call. Works with either !PXE or PXENV+ API.
*
* Parameters:
* %bx : PXE API call number
* %ds:pxe_parameter_structure : Parameters for PXE API call
* Returns:
* %ax : PXE status code (not exit code)
* CF set if %ax is non-zero
*****************************************************************************
*/
pxe_call:
/* Preserve registers */
pushw %di
pushw %es
/* Set up registers for PXENV+ API. %bx already set up */
pushw %ds
popw %es
movw $pxe_parameter_structure, %di
/* Set up stack for !PXE API */
pushw %es
pushw %di
pushw %bx
/* Make the API call */
lcall *entry_segoff
/* Reset the stack */
addw $6, %sp
movw pxe_parameter_structure, %ax
clc
testw %ax, %ax
jz 1f
stc
1: /* Restore registers and return */
popw %es
popw %di
ret
/*****************************************************************************
* Subroutine: print PXE API call error message
*
* Parameters:
* %ax : PXE status code
* %bx : PXE API call number
* Returns:
* Nothing
*****************************************************************************
*/
print_pxe_error:
pushw %si
movw $10f, %si
call print_message
xchgw %ax, %bx
call print_hex_word
movw $20f, %si
call print_message
xchgw %ax, %bx
call print_hex_word
movw $30f, %si
call print_message
popw %si
ret
.section ".prefix.data", "aw", @progbits
10: .asciz " UNDI API call "
20: .asciz " failed: status code "
30: .asciz "\n"
.previous
/*****************************************************************************
* PXE data structures
*****************************************************************************
*/
.section ".prefix.data"
pxe_ss: .word 0
pxe_esp: .long 0
pxe_parameter_structure: .fill 20
undi_code_segoff:
undi_code_size: .word 0
undi_code_segment: .word 0
undi_data_segoff:
undi_data_size: .word 0
undi_data_segment: .word 0
/* The following fields are part of a struct undi_device */
undi_device:
pxenv_segoff:
pxenv_offset: .word 0
pxenv_segment: .word 0
ppxe_segoff:
ppxe_offset: .word 0
ppxe_segment: .word 0
entry_segoff:
entry_offset: .word 0
entry_segment: .word 0
undi_fbms_start: .word 0
undi_fbms_end: .word 0
pci_busdevfn: .word UNDI_NO_PCI_BUSDEVFN
isapnp_csn: .word UNDI_NO_ISAPNP_CSN
isapnp_read_port: .word UNDI_NO_ISAPNP_READ_PORT
pci_vendor: .word 0
pci_device: .word 0
flags:
.word ( UNDI_FL_INITIALIZED | UNDI_FL_STARTED | UNDI_FL_KEEP_ALL )
.equ undi_device_size, ( . - undi_device )
/*****************************************************************************
* Run gPXE main code
*****************************************************************************
*/
.section ".prefix"
run_gpxe:
/* Install gPXE */
call install
/* Set up real-mode stack */
movw %bx, %ss
movw $_estack16, %sp
#ifdef PXELOADER_KEEP_UNDI
/* Copy our undi_device structure to the preloaded_undi variable */
movw %bx, %es
movw $preloaded_undi, %di
movw $undi_device, %si
movw $undi_device_size, %cx
rep movsb
#endif
/* Retrieve PXE %ss:esp */
movw pxe_ss, %di
movl pxe_esp, %ebp
/* Jump to .text16 segment with %ds pointing to .data16 */
movw %bx, %ds
pushw %ax
pushw $1f
lret
.section ".text16", "ax", @progbits
1:
/* Run main program */
pushl $main
pushw %cs
call prot_call
popl %ecx /* discard */
/* Uninstall gPXE */
call uninstall
/* Restore PXE stack */
movw %di, %ss
movl %ebp, %esp
/* Check PXE stack magic */
popl %eax
cmpl $STACK_MAGIC, %eax
jne 1f
/* PXE stack OK: return to caller */
popw %ds
popw %es
popw %fs
popw %gs
popal
popfl
xorw %ax, %ax /* Return success */
lret
1: /* PXE stack corrupt or removed: use INT 18 */
int $0x18
.previous