Updated to work with libprefix.
This commit is contained in:
Michael Brown
parent
29340d7728
commit
9f86754f90
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@ -1,16 +1,9 @@
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/* Offsets of words containing ROM's CS and size (in 512 byte blocks)
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* from start of floppy boot block at 0x7c00
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* Offsets must match those in etherboot.h
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*/
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#define FLOPPY_SEGMENT 0x7c0
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#define PXENV_UNDI_CLEANUP 0x02
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#define PXENV_UNDI_SHUTDOWN 0x05
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#define PXENV_STOP_UNDI 0x15
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#define PXENV_UNLOAD_STACK 0x70
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#define PXENV_STOP_BASE 0x76
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#define PUSHA_SIZE 16
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#define PXE_STACK_MAGIC 0x57ac /* 'STac' */
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.text
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@ -22,21 +15,35 @@
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* Entry point: set cs, ds, bp, print welcome message
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*****************************************************************************
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*/
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_prefix:
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jmp $FLOPPY_SEGMENT, $code_start-_prefix
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jmp $0x7c0, $code_start
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10: .asciz "PXE->EB "
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code_start:
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pusha /* Preserve all registers */
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push %ds
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movw %sp, %bp /* %bp must be preserved, hence do
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* this after the pusha */
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push $PXE_STACK_MAGIC /* PXE stack magic marker */
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push %cs /* Set up data segment */
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pop %ds
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mov $0x40, %cx /* Set up %fs for access to 40:13 */
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mov %cx, %fs
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movw $10b-_prefix, %si /* Print welcome message */
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/* Preserve registers for return to PXE stack */
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pushfl
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pushal
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pushw %gs
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pushw %fs
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pushw %es
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pushw %ds
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pushw %ss
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pushw %cs
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pushw $PXE_STACK_MAGIC /* PXE stack magic marker */
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/* Set up stack just below 0x7c00 */
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pushw %ss
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popw %es
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movw %sp, %di
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xorw %ax, %ax
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movw %ax, %ss
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movw $0x7c00, %sp
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pushw %es /* Save old PXE stack pointer */
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pushw %di
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/* Set up our other segment registers */
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pushw %cs
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popw %ds
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movw $0x40, %ax /* BIOS data segment access */
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movw %ax, %fs
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/* Print welcome message */
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movw $10b, %si
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call print_message
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/*****************************************************************************
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@ -44,12 +51,12 @@ code_start:
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*****************************************************************************
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*/
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detect_pxe:
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les 4+PUSHA_SIZE+2(%bp), %di /* !PXE structure */
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les %es:54(%di), %di /* !PXE structure */
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cmpl $0x45585021, %es:(%di) /* '!PXE' signature */
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je detected_pxe
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mov $0x5650, %ax
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movw $0x5650, %ax
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int $0x1a
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cmp $0x564e, %ax
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cmpw $0x564e, %ax
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jne detected_nothing
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cmpl $0x4e455850, %es:(%bx) /* 'PXEN' signature */
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jne detected_nothing
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@ -57,49 +64,45 @@ detect_pxe:
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je detected_pxenv
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detected_nothing:
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movw $10f-_prefix, %si
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movw $10f, %si
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call print_message
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jmp finished_with_error
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10: .asciz "No PXE "
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detected_pxenv: /* es:bx points to PXENV+ structure */
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push %es
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push %bx
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push %es:0x24(%bx) /* UNDI code segment */
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push %es:0x26(%bx) /* UNDI code size */
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push %es:0x20(%bx) /* UNDI data segment */
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push %es:0x22(%bx) /* UNDI data size */
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pushw %es
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pushw %bx
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pushw %es:0x24(%bx) /* UNDI code segment */
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pushw %es:0x26(%bx) /* UNDI code size */
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pushw %es:0x20(%bx) /* UNDI data segment */
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pushw %es:0x22(%bx) /* UNDI data size */
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les %es:0x0a(%bx), %di /* Entry point to %es:%di */
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movw $10f-_prefix, %si
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movw $10f, %si
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jmp pxe_setup_done
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10: .asciz "PXENV+ "
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detected_pxe: /* es:di points to !PXE structure */
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push %es
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push %di
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push %es:0x30(%di) /* UNDI code segment */
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push %es:0x36(%di) /* UNDI code size */
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push %es:0x28(%di) /* UNDI data segment */
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push %es:0x2e(%di) /* UNDI data size */
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pushw %es
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pushw %di
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pushw %es:0x30(%di) /* UNDI code segment */
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pushw %es:0x36(%di) /* UNDI code size */
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pushw %es:0x28(%di) /* UNDI data segment */
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pushw %es:0x2e(%di) /* UNDI data size */
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les %es:0x10(%di), %di /* Entry point to %es:%di */
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movw $10f-_prefix, %si
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movw $10f, %si
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jmp pxe_setup_done
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10: .asciz "!PXE "
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pxe_setup_done:
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mov %es, pxe_entry_segment - _prefix
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mov %di, pxe_entry_offset - _prefix
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pop %ax
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mov %ax, undi_data_size - _prefix
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pop %ax
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mov %ax, undi_data_segment - _prefix
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pop %ax
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mov %ax, undi_code_size - _prefix
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pop %ax
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mov %ax, undi_code_segment - _prefix
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movw %es, pxe_entry_segment
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movw %di, pxe_entry_offset
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popw undi_data_size
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popw undi_data_segment
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popw undi_code_size
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popw undi_code_segment
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call print_message
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pop %di
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pop %es /* Exit with %es:%di containing structure address */
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popw %di
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popw %es /* Exit with %es:%di containing structure address */
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/*****************************************************************************
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* Print information about located structure
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@ -107,11 +110,11 @@ pxe_setup_done:
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*/
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print_structure_information:
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call print_segoff /* %es:%di contains address of structure */
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les %ds:(pxe_entry_segoff - _prefix), %di
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les pxe_entry_segoff, %di
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call print_segoff
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les %ds:(undi_code_segoff - _prefix), %di
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les undi_code_segoff, %di
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call print_segoff
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les %ds:(undi_data_segoff - _prefix), %di
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les undi_data_segoff, %di
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call print_segoff
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/*****************************************************************************
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@ -119,17 +122,17 @@ print_structure_information:
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*****************************************************************************
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*/
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#ifdef PXELOADER_KEEP_ALL
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xor %ax, %ax /* Force zero flag to show success */
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xorw %ax, %ax /* Force zero flag to show success */
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jmp do_not_free_base_mem /* Skip the unloading */
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#endif /* PXELOADER_KEEP_ALL */
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unload_pxe:
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mov $PXENV_UNLOAD_STACK, %bx
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movw $PXENV_UNLOAD_STACK, %bx
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call pxe_call
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mov $PXENV_STOP_UNDI, %bx
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movw $PXENV_STOP_UNDI, %bx
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call pxe_call
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pushfw /* Ignore PXENV_UNDI_CLEANUP errors */
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mov $PXENV_UNDI_CLEANUP, %bx
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movw $PXENV_UNDI_CLEANUP, %bx
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call pxe_call
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popfw
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/* On exit, zero flag is set iff all calls were successful */
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@ -141,45 +144,45 @@ unload_pxe:
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free_base_mem:
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jnz do_not_free_base_mem /* Using zero flag from unload_pxe */
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mov undi_code_segment - _prefix, %bx
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mov undi_data_segment - _prefix, %cx
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mov undi_code_size - _prefix, %ax
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cmp %bx, %cx
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movw undi_code_segment, %bx
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movw undi_data_segment, %cx
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movw undi_code_size, %ax
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cmpw %bx, %cx
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jb 1f
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mov %cx, %bx
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mov undi_data_size - _prefix, %ax
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1: add $0x0f, %ax /* Round up to next segment */
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shr $4, %ax
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add %bx, %ax /* Highest segment address into %ax */
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add $(1024 / 16 - 1), %ax /* Round up to next kb */
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shr $6, %ax /* New free basemem size in %ax */
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mov %fs:(0x13), %bx /* Old free base memory in %bx */
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mov %ax, %fs:(0x13) /* Store new free base memory size */
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movw %cx, %bx
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movw undi_data_size, %ax
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1: addw $0x0f, %ax /* Round up to next segment */
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shrw $4, %ax
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addw %bx, %ax /* Highest segment address into %ax */
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addw $(1024 / 16 - 1), %ax /* Round up to next kb */
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shrw $6, %ax /* New free basemem size in %ax */
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movw %fs:(0x13), %bx /* Old free base memory in %bx */
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movw %ax, %fs:(0x13) /* Store new free base memory size */
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/* Note that zero_mem_loop will also zero out our stack, so make
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* sure the stack is empty at this point.
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*/
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mov %ax, %dx
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sub %bx, %dx /* numberof kb to zero in %dx */
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shl $6, %bx /* Segment address into %bx */
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movw %ax, %dx
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subw %bx, %dx /* numberof kb to zero in %dx */
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shlw $6, %bx /* Segment address into %bx */
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zero_mem_loop:
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mov %bx, %es /* kB boundary into %es:00 */
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xor %ax, %ax
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xor %di, %di
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mov $0x400, %cx
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movw %bx, %es /* kB boundary into %es:00 */
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xorw %ax, %ax
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xorw %di, %di
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movw $0x400, %cx
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rep stosb /* fill kB with zeroes */
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add $(1024 / 16), %bx
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dec %dx
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addw $(1024 / 16), %bx
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decw %dx
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jnz zero_mem_loop
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/* Will exit here with zero flag set, so no need to set it explicitly
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* in order to indicate success.
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*/
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do_not_free_base_mem:
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pushf /* Save success (zero) flag status */
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mov %fs:(0x13), %ax /* Free base memory in %ax */
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pushfw /* Save success (zero) flag status */
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movw %fs:(0x13), %ax /* Free base memory in %ax */
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call print_hex_word /* Print free base memory */
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popf /* Restore success (zero) flag */
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popfw /* Restore success (zero) flag */
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/*****************************************************************************
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* Exit point
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@ -188,92 +191,16 @@ do_not_free_base_mem:
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*****************************************************************************
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*/
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finished:
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movw $10f-_prefix, %si
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movw $10f, %si
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jz 1f
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finished_with_error:
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movw $20f-_prefix, %si
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movw $20f, %si
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1:
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call print_message
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jmp 99f
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jmp run_etherboot
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10: .asciz " ok\n"
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20: .asciz " err\n"
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/* We place a stack here. It doesn't get used until after all
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* the above code is finished, so we can happily write all
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* over it. Putting the stack here ensures that it doesn't
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* accidentally go over the 512 byte threshold, which would
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* cause problems when returning via start32's prefix
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* relocation mechanism.
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*/
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_estack:
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99:
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/*****************************************************************************
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* Run Etherboot main code
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*****************************************************************************
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*/
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run_etherboot:
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/* Very temporarily switch stacks to one internal to the
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* prefix. Do this because the stack provided by the PXE ROM
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* could be absolutely anywhere, including in an area of
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* memory that the call to prelocate will vapourise...
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*/
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pushw %ss /* PXE stack pointer to ES:DI */
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popw %es
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movw %sp, %di
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pushw %ds /* Set up stack in "safe" area */
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popw %ss
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movw $_estack-_prefix, %sp
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pushw %es /* Record PXE stack pointer */
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pushw %di
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/* Relocate payload and stack to claimed base memory */
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pushw $4 /* Preserve old PXE stack pointer */
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call prelocate
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popw %ax /* Remove parameter */
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pushl $4 /* Preserve old PXE stack pointer */
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pushw $0 /* Indicate prefix exit mechanism */
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jmp _start /* Run Etherboot */
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.section ".text16", "ax", @progbits
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prefix_exit:
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pushw %cs /* Set %ds, %bp for access to text */
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popw %ds
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call 1f
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1: popw %bp
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popw %di /* Old PXE stack to %es:di */
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popw %es
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cmpw $PXE_STACK_MAGIC, %es:0(%di) /* See if PXE stack intact */
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jne exit_via_int18
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exit_via_pxe: /* Stack OK, return to PXE */
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push %es /* Restore PXE stack pointer */
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pop %ss
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mov %di, %sp
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pop %ax /* Discard PXE_STACK_MAGIC marker */
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leaw (10f-1b)(%bp), %si
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call print_exit_message
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pop %ds /* Restore PXE's DS */
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popa /* Restore PXE's other registers */
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movw $0, %ax /* Return PXENV_STATUS_SUCCESS */
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lret /* Return control to PXE ROM */
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10: .asciz "EB->PXE\r\n"
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exit_via_int18: /* Stack damaged, do int 18 */
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leaw (10f-1b)(%bp), %si
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call print_exit_message
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int $0x18
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10: .asciz "EB->BIOS\r\n"
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print_exit_message:
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movw $0x0007, %bx /* page 0, attribute 7 (normal) */
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movb $0x0e, %ah /* write char, tty mode */
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1: lodsb
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testb %al, %al
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je 2f
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int $0x10
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jmp 1b
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2: ret
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prefix_exit_end:
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.previous
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/*****************************************************************************
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* Subroutine: print character in %al (with LF -> LF,CR translation)
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*****************************************************************************
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@ -305,17 +232,17 @@ print_message:
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*****************************************************************************
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*/
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print_hex_word:
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mov $4, %cx
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movw $4, %cx
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1:
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push %ax
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shr $12, %ax
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pushw %ax
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shrw $12, %ax
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/* Courtesy of Norbert Juffa <norbert.juffa@amd.com> */
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cmp $10, %al
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sbb $0x69, %al
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cmpb $10, %al
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sbbb $0x69, %al
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das
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call print_character
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pop %ax
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shl $4, %ax
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popw %ax
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shlw $4, %ax
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loop 1b
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ret
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@ -324,15 +251,15 @@ print_hex_word:
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*****************************************************************************
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*/
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print_segoff:
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push %di
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push %es
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pop %ax
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pushw %di
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pushw %es
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popw %ax
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call print_hex_word
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movb $0x3a,%al /* ':' */
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call print_character
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pop %ax
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popw %ax
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call print_hex_word
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mov $0x20, %al /* ' ' */
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movb $0x20, %al /* ' ' */
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call print_character
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ret
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@ -346,24 +273,24 @@ print_segoff:
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*/
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pxe_call:
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/* Set up registers for PXENV+ API. %bx already set up */
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push %ds
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pop %es
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mov $pxe_parameter_structure - _prefix, %di
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pushw %ds
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popw %es
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movw $pxe_parameter_structure, %di
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/* Set up stack for !PXE API */
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pushw %cs
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pushw %di
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pushw %bx
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/* Make the API call */
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lcall *(pxe_entry_segoff - _prefix)
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lcall *pxe_entry_segoff
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/* Reset the stack */
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add $6, %sp
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mov pxe_parameter_structure - _prefix, %ax
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push %ax
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addw $6, %sp
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movw pxe_parameter_structure, %ax
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pushw %ax
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call print_hex_word
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mov $0x20, %ax /* ' ' */
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movw $0x20, %ax /* ' ' */
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call print_character
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pop %bx
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or %bx, pxe_overall_status - _prefix
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popw %bx
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orw %bx, pxe_overall_status
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ret
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/*****************************************************************************
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@ -389,7 +316,73 @@ pxe_parameter_structure:
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.word 0
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.word 0,0,0,0,0
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end_of_pxeloader:
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/*****************************************************************************
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* Run Etherboot main code
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*****************************************************************************
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*/
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run_etherboot:
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/* Install Etherboot */
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call install
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.balign 16, 0
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payload:
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/* Jump to .text16 segment with %ds pointing to .data16*/
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movw %bx, %ds
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pushw %ax
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pushw $1f
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lret
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.section ".text16", "ax", @progbits
|
||||
1:
|
||||
/* Original PXE stack pointer to es:di. We must hold it in
|
||||
* registers, because our current stack may be vapourised by
|
||||
* the time main() returns. (main() will still be able to
|
||||
* return, because prot_call() transfers the return address to
|
||||
* the internal stack and back again).
|
||||
*/
|
||||
popw %di
|
||||
popw %es
|
||||
|
||||
/* Run main program */
|
||||
pushl $main
|
||||
pushw %cs
|
||||
call prot_call
|
||||
popl %eax /* discard */
|
||||
|
||||
/* If original PXE stack is intact, return via PXE, else via INT 18 */
|
||||
cmpw $PXE_STACK_MAGIC, %es:0(%di)
|
||||
jne exit_via_int18
|
||||
exit_via_pxe: /* Stack OK, return to PXE */
|
||||
movw $exit_via_pxe_message, %si
|
||||
call print_exit_message
|
||||
pushw %es /* Restore original PXE stack */
|
||||
popw %ss
|
||||
movw %di, %sp
|
||||
popw %ax /* discard PXE_STACK_MAGIC */
|
||||
popw %ax /* discard %cs */
|
||||
popw %ax /* discard %ss */
|
||||
popw %ds
|
||||
popw %es
|
||||
popw %fs
|
||||
popw %gs
|
||||
popal
|
||||
popfl
|
||||
xorw %ax, %ax /* Return PXENV_STATUS_SUCCESS */
|
||||
lret
|
||||
exit_via_int18: /* Stack damaged, do int 18 */
|
||||
movw $exit_via_int18_message, %si
|
||||
call print_exit_message
|
||||
int $0x18
|
||||
|
||||
print_exit_message:
|
||||
movw $0x0007, %bx /* page 0, attribute 7 (normal) */
|
||||
movb $0x0e, %ah /* write char, tty mode */
|
||||
1: lodsb
|
||||
testb %al, %al
|
||||
je 2f
|
||||
int $0x10
|
||||
jmp 1b
|
||||
2: ret
|
||||
|
||||
.section ".data16", "aw", @progbits
|
||||
exit_via_pxe_message:
|
||||
.asciz "EB->PXE\r\n"
|
||||
exit_via_int18_message:
|
||||
.asciz "EB->BIOS\r\n"
|
||||
|
|
|
|||
Reference in New Issue