xref: /src/sys/arch/vax/boot/xxboot/start.S

/*	$NetBSD: start.S,v 1.7 2020/04/06 01:43:26 snj Exp $ */
/*
 * Copyright (c) 1995 Ludd, University of Lule}, Sweden.
 * All rights reserved.
 *
 * This code is derived from software contributed to Ludd by
 * Bertram Barth.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

 /* All bugs are subject to removal without further notice */


#define _LOCORE

#define	__HAVE_OLD_DISKLABEL	/* not automatically added due to _LOCORE */
#define OMIT_DKTYPENUMS
#define OMIT_FSTYPENUMS
#include "sys/disklabel.h"

#include "../include/mtpr.h"
#include "../include/asm.h"

_C_LABEL(_start):
_C_LABEL(start):
	.globl _C_LABEL(start)	# this is the symbolic name for the start
	.globl _C_LABEL(_start) # of code to be relocated. We can use this
				# to get the actual/real address (pc-rel)
				# or to get the relocated address (abs).

.org	0x00			# uVAX booted from TK50 starts here
	brb	from_0x00	# continue behind dispatch-block

# At offset 0x02 we have a dual used area: VMB.EXE starts execution here,
# and uVAX-ROM looks for a pointer to a parameter block. We arrange for
# the parameter block offset to disassemble as a CASEL instructions which
# falls through to 0x08.
.org	0x02			# information used by uVAX-ROM
	.byte	0xcf		# offset in words to identification area
	.byte	1		# this byte must be 1
	.word	0		# logical block number (word swapped)
	.word	0		# of the secondary image

.org	0x08			#
	brb	from_0x08	# skip ...

.org	0x0C			# 11/750  & 8200 starts here
	movzbl	$1,_C_LABEL(from)# We booted from "old" rom.
	brw	cont_750


from_0x00:			# uVAX from TK50
	brw	start_uvax	# all uVAXen continue there

from_0x08:			# Any machine from VMB
	movzbl	$4,_C_LABEL(from)		# Booted from full VMB
	/*
	 * Read in block 1-15.
	 */
	movl	52(%r11), %r7	# load iovec/bqo into %r7
	addl3	(%r7), %r7, %r6	# load qio into %r6
	pushl	%r11		# base of rpb
	pushl	$0		# virtual-flag
	pushl	$33		# read-logical-block
	pushl	$1		# lbn to start reading
	pushl	$7680		# number of bytes to read
	pushab	start_uvax	# buffer-address
	calls	$6, (%r6)	# call the qio-routine
	brw	start_uvax

# the complete area reserved for label
# must be empty (i.e. filled with zeroes).
# disklabel(8) checks that before installing
# the bootblocks over existing label.

.org	LABELOFFSET
	.globl	_C_LABEL(romlabel)
_C_LABEL(romlabel):
	.long	0

.org	LABELOFFSET + d_end_
# Make sure the parameter block is past the disklabel.
# If not, the next .org would try to move backwards.

/*
 * Parameter block for uVAX boot.
 */
#define VOLINFO		0	/* 1=single-sided  81=double-sided volumes */
#define SISIZE		16	/* size in blocks of secondary image */
#define SILOAD		0	/* load offset (usually 0) from the default */
#define SIOFF		0x200	/* byte offset into secondary image */

.org	0x19e	# do not move, see comment earlier about CASEL
	.byte	0x18		# must be 0x18
	.byte	0x00		# must be 0x00 (MBZ)
	.byte	0x00		# any value
	.byte	0xFF - (0x18 + 0x00 + 0x00)
		/* 4th byte holds 1s' complement of sum of previous 3 bytes */

	.byte	0x00		# must be 0x00 (MBZ)
	.byte	VOLINFO
	.byte	0x00		# any value
	.byte	0x00		# any value

	.long	SISIZE		# size in blocks of secondary image
	.long	SILOAD		# load offset (usually 0)
	.long	SIOFF		# byte offset into secondary image
	.long	(SISIZE + SILOAD + SIOFF)	# sum of previous 3


	.align	2
	.globl	_C_LABEL(from)
_C_LABEL(from):
	.long	0

/*
 * After bootblock (LBN0) has been loaded into the first page
 * of good memory by 11/750's ROM-code (transfer address
 * of bootblock-code is: base of good memory + 0x0C) registers
 * are initialized as:
 *	R0:	type of boot-device
 *			0:	Massbus device
 *			1:	RK06/RK07
 *			2:	RL02
 *			17:	UDA50
 *			35:	TK50
 *			64:	TU58
 *	R1:	(UBA) address of UNIBUS I/O-page
 *		(MBA) address of boot device's adapter
 *	R2:	(UBA) address of the boot device's CSR
 *		(MBA) controller number of boot device
 *	R6:	address of driver subroutine in ROM
 *
 * cont_750 reads in LBN1-15 for further execution.
 */
cont_750:
	movl	$_C_LABEL(start), %sp	# move stack to avoid clobbering the code
	pushr	$0x131		# save clobbered registers
	clrl	%r4		# %r4 == # of blocks transferred
	movab	_C_LABEL(start),%r5	# %r5 have base address for next transfer
	pushl	%r5		# ...on stack also (Why?)
1:	incl	%r4		# increment block count
	movl	%r4,%r8		# LBN is in %r8 for rom routine
	addl2	$0x200,%r5	# Increase address for next read
	cmpl	$16,%r4		# read 15 blocks?
	beql	2f		# Yep
	movl	%r5,(%sp)		# move address to stack also
	jsb	(%r6)		# read 512 bytes
	blbs	%r0,1b		# jump if read succeeded
	halt			# otherwise die...
2:	tstl	(%sp)+		# remove boring arg from stack
	popr	$0x131		# restore clobbered registers
	brw	start_all	# Ok, continue...

/* uVAX main entry is at the start of the second disk block.  This is
 * needed for multi-arch CD booting where multiple architecture need
 * to shove stuff in boot block 0.
 */
	.org	0x200		# uVAX booted from disk starts here

start_uvax:
	movzbl	$2,_C_LABEL(from)	# Booted from subset-VMB
	brb	start_all

/*
 * start_all: stack already at RELOC, we save registers, move ourself
 * to RELOC and loads boot.
 */
start_all:
	movl	$_C_LABEL(start), %sp	# move stack to a better
	pushr	$0x1fff			# save all regs, used later.

	subl3	$_C_LABEL(start), $_C_LABEL(edata), %r0
					# get size of text+data (w/o bss)
	moval	_C_LABEL(start), %r1	# get actual base-address of code
	subl3	$_C_LABEL(start), $_C_LABEL(end), %r2
					# get complete size (incl. bss)
	movl	$_C_LABEL(start), %r3	# get relocated base-address of code
	movc5	%r0, (%r1), $0, %r2, (%r3)	# copy code to new location

	movpsl	-(%sp)
	movl	$relocated, -(%sp)	# return-address on top of stack
	rei				# can be replaced with new address
relocated:				# now relocation is done !!!
	movl	%sp, _C_LABEL(bootregs)
	calls	$0, _C_LABEL(Xmain)	# call Xmain (gcc workaround)which is
	halt				# not intended to return ...

/*
 * hoppabort() is called when jumping to the newly loaded program.
 */
ENTRY(hoppabort, 0)
	movl    4(%ap),%r6
	movl	_C_LABEL(rpb),%r11
	mnegl	$1,%ap		# Hack to figure out boot device.
	movpsl	-(%sp)
	pushab	2(%r6)
	mnegl	$1,_C_LABEL(vax_load_failure)
	rei
#	calls	$0,(%r6)
	halt

ENTRY(unit_init, R6|R7|R8|R9|R10|R11)
	mfpr	$17,%r7			# Wanted bu KDB
	movl	4(%ap),%r0		# init routine address
	movl	8(%ap),%r9		# RPB in %r9
	movl	12(%ap),%r1		# VMB argument list
	callg	(%r1),(%r0)
	ret

# A bunch of functions unwanted in boot blocks.
ENTRY(getchar, 0)
	halt

#ifndef USE_PRINTF
ENTRY(putchar, 0)
	ret

ENTRY(printf, 0)
	ret
#endif

ENTRY(panic, 0)
	halt