# x86 bootblock used in migration test
# repeatedly increments the first byte of each page in a 100MB
# range.
# Outputs an initial 'A' on serial followed by repeated 'B's
#
# Copyright (c) 2016 Red Hat, Inc. and/or its affiliates
# This work is licensed under the terms of the GNU GPL, version 2 or later.
# See the COPYING file in the top-level directory.
#
# Author: dgilbert@redhat.com
.code16
.org 0x7c00
.file "fill.s"
.text
.globl start
.type start, @function
start: # at 0x7c00 ?
cli
lgdt gdtdesc
mov $1,%eax
mov %eax,%cr0 # Protected mode enable
data32 ljmp $8,$0x7c20
.org 0x7c20
.code32
# A20 enable - not sure I actually need this
inb $0x92,%al
or $2,%al
outb %al, $0x92
# set up DS for the whole of RAM (needed on KVM)
mov $16,%eax
mov %eax,%ds
mov $65,%ax
mov $0x3f8,%dx
outb %al,%dx
# bl keeps a counter so we limit the output speed
mov $0, %bl
mainloop:
# Start from 1MB
mov $(1024*1024),%eax
innerloop:
incb (%eax)
add $4096,%eax
cmp $(100*1024*1024),%eax
jl innerloop
inc %bl
jnz mainloop
mov $66,%ax
mov $0x3f8,%dx
outb %al,%dx
jmp mainloop
# GDT magic from old (GPLv2) Grub startup.S
.p2align 2 /* force 4-byte alignment */
gdt:
.word 0, 0
.byte 0, 0, 0, 0
/* -- code segment --
* base = 0x00000000, limit = 0xFFFFF (4 KiB Granularity), present
* type = 32bit code execute/read, DPL = 0
*/
.word 0xFFFF, 0
.byte 0, 0x9A, 0xCF, 0
/* -- data segment --
* base = 0x00000000, limit 0xFFFFF (4 KiB Granularity), present
* type = 32 bit data read/write, DPL = 0
*/
.word 0xFFFF, 0
.byte 0, 0x92, 0xCF, 0
gdtdesc:
.word 0x27 /* limit */
.long gdt /* addr */
/* I'm a bootable disk */
.org 0x7dfe
.byte 0x55
.byte 0xAA
