1172940Sjhb/*- 2172940Sjhb * Copyright (c) 2007 Yahoo!, Inc. 3172940Sjhb * All rights reserved. 4172940Sjhb * Written by: John Baldwin <jhb@FreeBSD.org> 5172940Sjhb * 6172940Sjhb * Redistribution and use in source and binary forms, with or without 7172940Sjhb * modification, are permitted provided that the following conditions 8172940Sjhb * are met: 9172940Sjhb * 1. Redistributions of source code must retain the above copyright 10172940Sjhb * notice, this list of conditions and the following disclaimer. 11172940Sjhb * 2. Redistributions in binary form must reproduce the above copyright 12172940Sjhb * notice, this list of conditions and the following disclaimer in the 13172940Sjhb * documentation and/or other materials provided with the distribution. 14172940Sjhb * 3. Neither the name of the author nor the names of any co-contributors 15172940Sjhb * may be used to endorse or promote products derived from this software 16172940Sjhb * without specific prior written permission. 17172940Sjhb * 18172940Sjhb * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19172940Sjhb * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20172940Sjhb * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21172940Sjhb * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22172940Sjhb * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23172940Sjhb * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24172940Sjhb * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25172940Sjhb * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26172940Sjhb * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27172940Sjhb * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28172940Sjhb * SUCH DAMAGE. 29172940Sjhb * 30172940Sjhb * $FreeBSD: releng/10.3/sys/boot/i386/gptboot/gptldr.S 289358 2015-10-15 03:48:03Z cperciva $ 31173957Sjhb * 32173957Sjhb * Partly from: src/sys/boot/i386/boot2/boot1.S 1.31 33172940Sjhb */ 34172940Sjhb 35172940Sjhb/* Memory Locations */ 36172940Sjhb .set MEM_REL,0x700 # Relocation address 37172940Sjhb .set MEM_ARG,0x900 # Arguments 38172940Sjhb .set MEM_ORG,0x7c00 # Origin 39172940Sjhb .set MEM_BUF,0x8cec # Load area 40172940Sjhb .set MEM_BTX,0x9000 # BTX start 41172940Sjhb .set MEM_JMP,0x9010 # BTX entry point 42172940Sjhb .set MEM_USR,0xa000 # Client start 43172940Sjhb .set BDA_BOOT,0x472 # Boot howto flag 44172940Sjhb 45172940Sjhb/* Misc. Constants */ 46172940Sjhb .set SIZ_PAG,0x1000 # Page size 47172940Sjhb .set SIZ_SEC,0x200 # Sector size 48289358Scperciva .set COPY_BLKS,0x4 # Number of blocks 49289358Scperciva # to copy for boot2 50289358Scperciva .set COPY_BLK_SZ,0x8000 # Copy in 32k blocks; must be 51289358Scperciva # a multiple of 16 bytes 52172940Sjhb 53172940Sjhb .globl start 54172940Sjhb .code16 55172940Sjhb 56172940Sjhb/* 57172940Sjhb * Copy BTX and boot2 to the right locations and start it all up. 58172940Sjhb */ 59172940Sjhb 60172940Sjhb/* 61172940Sjhb * Setup the segment registers to flat addressing (segment 0) and setup the 62172940Sjhb * stack to end just below the start of our code. 63172940Sjhb */ 64172940Sjhbstart: xor %cx,%cx # Zero 65172940Sjhb mov %cx,%es # Address 66172940Sjhb mov %cx,%ds # data 67172940Sjhb mov %cx,%ss # Set up 68172940Sjhb mov $start,%sp # stack 69172940Sjhb 70172940Sjhb/* 71172940Sjhb * BTX is right after us at 'end'. We read the length of BTX out of 72172940Sjhb * its header to find boot2. We need to copy boot2 to MEM_USR and BTX 73172940Sjhb * to MEM_BTX. Since those might overlap, we have to copy boot2 74172940Sjhb * backwards first and then copy BTX. We aren't sure exactly how long 75289358Scperciva * boot2 is, but it's currently under 128kB so we'll copy 4 blocks of 32kB 76289358Scperciva * each; this can be adjusted via COPY_BLK and COPY_BLK_SZ above. 77172940Sjhb */ 78172940Sjhb mov $end,%bx # BTX 79172940Sjhb mov 0xa(%bx),%si # Get BTX length and set 80172940Sjhb add %bx,%si # %si to start of boot2 81289358Scperciva dec %si # Set %ds:%si to point at the 82289358Scperciva mov %si,%ax # last byte we want to copy 83289358Scperciva shr $4,%ax # from boot2, with %si made as 84289358Scperciva add $(COPY_BLKS*COPY_BLK_SZ/16),%ax # small as possible. 85289358Scperciva and $0xf,%si # 86289358Scperciva mov %ax,%ds # 87289358Scperciva mov $MEM_USR/16,%ax # Set %es:(-1) to point at 88289358Scperciva add $(COPY_BLKS*COPY_BLK_SZ/16),%ax # the last byte we 89289358Scperciva mov %ax,%es # want to copy boot2 into. 90289358Scperciva mov $COPY_BLKS,%bx # Copy COPY_BLKS 32k blocks 91289358Scpercivacopyloop: 92289358Scperciva add $COPY_BLK_SZ,%si # Adjust %ds:%si to point at 93289358Scperciva mov %ds,%ax # the end of the next 32k to 94289358Scperciva sub $COPY_BLK_SZ/16,%ax # copy from boot2 95289358Scperciva mov %ax,%ds 96289358Scperciva mov $COPY_BLK_SZ-1,%di # Adjust %es:%di to point at 97289358Scperciva mov %es,%ax # the end of the next 32k into 98289358Scperciva sub $COPY_BLK_SZ/16,%ax # which we want boot2 copied 99172940Sjhb mov %ax,%es 100289358Scperciva mov $COPY_BLK_SZ,%cx # Copy 32k 101172940Sjhb std 102172940Sjhb rep movsb 103289358Scperciva dec %bx 104289358Scperciva jnz copyloop 105172940Sjhb mov %cx,%ds # Reset %ds and %es 106172940Sjhb mov %cx,%es 107289358Scperciva mov $end,%bx # BTX 108172940Sjhb mov 0xa(%bx),%cx # Get BTX length and set 109172940Sjhb mov %bx,%si # %si to end of BTX 110172940Sjhb mov $MEM_BTX,%di # %di -> end of BTX at 111172940Sjhb add %cx,%si # MEM_BTX 112172940Sjhb add %cx,%di 113172940Sjhb dec %si 114172940Sjhb dec %di 115172940Sjhb rep movsb # Move BTX 116172940Sjhb cld # String ops inc 117172940Sjhb/* 118172940Sjhb * Enable A20 so we can access memory above 1 meg. 119172940Sjhb * Use the zero-valued %cx as a timeout for embedded hardware which do not 120172940Sjhb * have a keyboard controller. 121172940Sjhb */ 122172940Sjhbseta20: cli # Disable interrupts 123172940Sjhbseta20.1: dec %cx # Timeout? 124172940Sjhb jz seta20.3 # Yes 125172940Sjhb inb $0x64,%al # Get status 126172940Sjhb testb $0x2,%al # Busy? 127172940Sjhb jnz seta20.1 # Yes 128172940Sjhb movb $0xd1,%al # Command: Write 129172940Sjhb outb %al,$0x64 # output port 130172940Sjhbseta20.2: inb $0x64,%al # Get status 131172940Sjhb testb $0x2,%al # Busy? 132172940Sjhb jnz seta20.2 # Yes 133172940Sjhb movb $0xdf,%al # Enable 134172940Sjhb outb %al,$0x60 # A20 135172940Sjhbseta20.3: sti # Enable interrupts 136172940Sjhb 137172940Sjhb/* 138172940Sjhb * Save drive number from BIOS so boot2 can see it and start BTX. 139172940Sjhb */ 140172940Sjhb movb %dl,MEM_ARG 141172940Sjhb jmp MEM_JMP # Start BTX 142172940Sjhbend: 143