! setup.S Copyright (C) 1991, 1992 Linus Torvalds
!
! setup.s is responsible for getting the system data from the BIOS,
! and putting them into the appropriate places in system memory.
! both setup.s and system has been loaded by the bootblock.
!
! This code asks the bios for memory/disk/other parameters, and
! puts them in a "safe" place: 0x90000-0x901FF, ie where the
! boot-block used to be. It is then up to the protected mode
! system to read them from there before the area is overwritten
! for buffer-blocks.
!
! Move PS/2 aux init code to psaux.c
! (troyer@saifr00.cfsat.Honeywell.COM) 03Oct92
!
! some changes and additional features by Christoph Niemann,
! March 1993/June 1994 (Christoph.Niemann@linux.org)
!
! add APM BIOS checking by Stephen Rothwell, May 1994
! (Stephen.Rothwell@pd.necisa.oz.au)
!
! High load stuff, initrd support and position independency
! by Hans Lermen & Werner Almesberger, February 1996
! <lermen@elserv.ffm.fgan.de>, <almesber@lrc.epfl.ch>
!
! Video handling moved to video.S by Martin Mares, March 1996
! <mj@k332.feld.cvut.cz>
! NOTE! These had better be the same as in bootsect.s!
#define __ASSEMBLY__
#include <linux/config.h>
#include <asm/segment.h>
#include <linux/version.h>
#include <linux/compile.h>
! Signature words to ensure LILO loaded us right
#define SIG1 0xAA55
#define SIG2 0x5A5A
INITSEG = DEF_INITSEG ! 0x9000, we move boot here - out of the way
SYSSEG = DEF_SYSSEG ! 0x1000, system loaded at 0x10000 (65536).
SETUPSEG = DEF_SETUPSEG ! 0x9020, this is the current segment
! ... and the former contents of CS
DELTA_INITSEG = SETUPSEG - INITSEG ! 0x0020
.globl begtext, begdata, begbss, endtext, enddata, endbss
.text
begtext:
.data
begdata:
.bss
begbss:
.text
entry start
start:
jmp start_of_setup
! ------------------------ start of header --------------------------------
!
! SETUP-header, must start at CS:2 (old 0x9020:2)
!
.ascii "HdrS" ! Signature for SETUP-header
.word 0x0201 ! Version number of header format
! (must be >= 0x0105
! else old loadlin-1.5 will fail)
realmode_swtch: .word 0,0 ! default_switch,SETUPSEG
start_sys_seg: .word SYSSEG
.word kernel_version ! pointing to kernel version string
! note: above part of header is compatible with loadlin-1.5 (header v1.5),
! must not change it
type_of_loader: .byte 0 ! = 0, old one (LILO, Loadlin,
! Bootlin, SYSLX, bootsect...)
! else it is set by the loader:
! 0xTV: T=0 for LILO
! T=1 for Loadlin
! T=2 for bootsect-loader
! T=3 for SYSLX
! T=4 for ETHERBOOT
! V = version
loadflags: .byte 0 ! unused bits =0 (reserved for future development)
LOADED_HIGH = 1 ! bit within loadflags,
! if set, then the kernel is loaded high
CAN_USE_HEAP = 0x80 ! if set, the loader also has set heap_end_ptr
! to tell how much space behind setup.S
| can be used for heap purposes.
! Only the loader knows what is free!
setup_move_size: .word 0x8000 ! size to move, when we (setup) are not
! loaded at 0x90000. We will move ourselves
! to 0x90000 then just before jumping into
! the kernel. However, only the loader
! know how much of data behind us also needs
! to be loaded.
code32_start: .long 0x1000 ! here loaders can put a different
! start address for 32-bit code.
! 0x1000 = default for zImage
! 0x100000 = default for big kernel
ramdisk_image: .long 0 ! address of loaded ramdisk image
! Here the loader (or kernel generator) puts
! the 32-bit address were it loaded the image.
! This only will be interpreted by the kernel.
ramdisk_size: .long 0 ! its size in bytes
bootsect_kludge:
.word bootsect_helper,SETUPSEG
heap_end_ptr: .word modelist+1024 ! space from here (exclusive) down to
! end of setup code can be used by setup
! for local heap purposes.
! ------------------------ end of header ----------------------------------
start_of_setup:
! Bootlin depends on this being done early
mov ax,#0x01500
mov dl,#0x81
int 0x13
#ifdef SAFE_RESET_DISK_CONTROLLER
! Reset the disk controller.
mov ax,#0x0000
mov dl,#0x80
int 0x13
#endif
! set DS=CS, we know that SETUPSEG == CS at this point
mov ax,cs ! aka #SETUPSEG
mov ds,ax
! Check signature at end of setup
cmp setup_sig1,#SIG1
jne bad_sig
cmp setup_sig2,#SIG2
jne bad_sig
jmp good_sig1
! Routine to print asciiz-string at DS:SI
prtstr: lodsb
and al,al
jz fin
call prtchr
jmp prtstr
fin: ret
! Space printing
prtsp2: call prtspc ! Print double space
prtspc: mov al,#0x20 ! Print single space (fall-thru!)
! Part of above routine, this one just prints ascii al
prtchr: push ax
push cx
xor bh,bh
mov cx,#0x01
mov ah,#0x0e
int 0x10
pop cx
pop ax
ret
beep: mov al,#0x07
jmp prtchr
no_sig_mess: .ascii "No setup signature found ..."
db 0x00
good_sig1:
jmp good_sig
! We now have to find the rest of the setup code/data
bad_sig:
mov ax,cs ! aka #SETUPSEG
sub ax,#DELTA_INITSEG ! aka #INITSEG
mov ds,ax
xor bh,bh
mov bl,[497] ! get setup sects from boot sector
sub bx,#4 ! LILO loads 4 sectors of setup
shl bx,#8 ! convert to words
mov cx,bx
shr bx,#3 ! convert to segment
add bx,#SYSSEG
seg cs
mov start_sys_seg,bx
! Move rest of setup code/data to here
mov di,#2048 ! four sectors loaded by LILO
sub si,si
mov ax,cs ! aka #SETUPSEG
mov es,ax
mov ax,#SYSSEG
mov ds,ax
rep
movsw
mov ax,cs ! aka #SETUPSEG
mov ds,ax
cmp setup_sig1,#SIG1
jne no_sig
cmp setup_sig2,#SIG2
jne no_sig
jmp good_sig
no_sig:
lea si,no_sig_mess
call prtstr
no_sig_loop:
jmp no_sig_loop
good_sig:
mov ax,cs ! aka #SETUPSEG
sub ax,#DELTA_INITSEG ! aka #INITSEG
mov ds,ax
! check if an old loader tries to load a big-kernel
seg cs
test byte ptr loadflags,#LOADED_HIGH ! have we a big kernel ?
jz loader_ok ! NO, no danger even for old loaders
! YES, we have a big-kernel
seg cs
cmp byte ptr type_of_loader,#0 ! have we one of the new loaders ?
jnz loader_ok ! YES, ok
! NO, we have an old loader, must give up
push cs
pop ds
lea si,loader_panic_mess
call prtstr
jmp no_sig_loop
loader_panic_mess:
.ascii "Wrong loader, giving up..."
db 0
loader_ok:
! Get memory size (extended mem, kB)
mov ah,#0x88
int 0x15
mov [2],ax
! Set the keyboard repeat rate to the max
mov ax,#0x0305
xor bx,bx ! clear bx
int 0x16
! Check for video adapter and its parameters and allow the
! user to browse video modes.
call video ! NOTE: we need DS pointing to bootsector
! Get hd0 data
xor ax,ax ! clear ax
mov ds,ax
lds si,[4*0x41]
mov ax,cs ! aka #SETUPSEG
sub ax,#DELTA_INITSEG ! aka #INITSEG
push ax
mov es,ax
mov di,#0x0080
mov cx,#0x10
push cx
cld
rep
movsb
! Get hd1 data
xor ax,ax ! clear ax
mov ds,ax
lds si,[4*0x46]
pop cx
pop es
mov di,#0x0090
rep
movsb
! Check that there IS a hd1 :-)
mov ax,#0x01500
mov dl,#0x81
int 0x13
jc no_disk1
cmp ah,#3
je is_disk1
no_disk1:
mov ax,cs ! aka #SETUPSEG
sub ax,#DELTA_INITSEG ! aka #INITSEG
mov es,ax
mov di,#0x0090
mov cx,#0x10
xor ax,ax ! clear ax
cld
rep
stosb
is_disk1:
! Check for PS/2 pointing device
mov ax,cs ! aka #SETUPSEG
sub ax,#DELTA_INITSEG ! aka #INITSEG
mov ds,ax
mov [0x1ff],#0 ! default is no pointing device
int 0x11 ! int 0x11: equipment determination
test al,#0x04 ! check if pointing device installed
jz no_psmouse
mov [0x1ff],#0xaa ! device present
no_psmouse:
#ifdef CONFIG_APM
! check for APM BIOS
! NOTE: DS is pointing to the bootsector
!
mov [64],#0 ! version == 0 means no APM BIOS
mov ax,#0x05300 ! APM BIOS installation check
xor bx,bx
int 0x15
jc done_apm_bios ! error -> no APM BIOS
cmp bx,#0x0504d ! check for "PM" signature
jne done_apm_bios ! no signature -> no APM BIOS
mov [64],ax ! record the APM BIOS version
mov [76],cx ! and flags
and cx,#0x02 ! Is 32 bit supported?
je done_apm_bios ! no ...
mov ax,#0x05304 ! Disconnect first just in case
xor bx,bx
int 0x15 ! ignore return code
mov ax,#0x05303 ! 32 bit connect
xor bx,bx
int 0x15
jc no_32_apm_bios ! error
mov [66],ax ! BIOS code segment
mov [68],ebx ! BIOS entry point offset
mov [72],cx ! BIOS 16 bit code segment
mov [74],dx ! BIOS data segment
mov [78],si ! BIOS code segment length
mov [80],di ! BIOS data segment length
jmp done_apm_bios
no_32_apm_bios:
and [76], #0xfffd ! remove 32 bit support bit
done_apm_bios:
#endif
! Now we want to move to protected mode ...
seg cs
cmp realmode_swtch,#0
jz rmodeswtch_normal
seg cs
callf far * realmode_swtch
jmp rmodeswtch_end
rmodeswtch_normal:
push cs
call default_switch
rmodeswtch_end:
! we get the code32 start address and modify the below 'jmpi'
! (loader may have changed it)
seg cs
mov eax,code32_start
seg cs
mov code32,eax
! Now we move the system to its rightful place
! ...but we check, if we have a big-kernel.
! in this case we *must* not move it ...
seg cs
test byte ptr loadflags,#LOADED_HIGH
jz do_move0 ! we have a normal low loaded zImage
! we have a high loaded big kernel
jmp end_move ! ... and we skip moving
do_move0:
mov ax,#0x100 ! start of destination segment
mov bp,cs ! aka #SETUPSEG
sub bp,#DELTA_INITSEG ! aka #INITSEG
seg cs
mov bx,start_sys_seg ! start of source segment
cld ! 'direction'=0, movs moves forward
do_move:
mov es,ax ! destination segment
inc ah ! instead of add ax,#0x100
mov ds,bx ! source segment
add bx,#0x100
sub di,di
sub si,si
mov cx,#0x800
rep
movsw
cmp bx,bp ! we assume start_sys_seg > 0x200,
! so we will perhaps read one page more then
! needed, but never overwrite INITSEG because
! destination is minimum one page below source
jb do_move
! then we load the segment descriptors
end_move:
mov ax,cs ! aka #SETUPSEG ! right, forgot this at first. didn't work :-)
mov ds,ax
! If we have our code not at 0x90000, we need to move it there now.
! We also then need to move the params behind it (commandline)
! Because we would overwrite the code on the current IP, we move
! it in two steps, jumping high after the first one.
mov ax,cs
cmp ax,#SETUPSEG
je end_move_self
cli ! make sure we really have interrupts disabled !
! because after this the stack should not be used
sub ax,#DELTA_INITSEG ! aka #INITSEG
mov dx,ss
cmp dx,ax
jb move_self_1
add dx,#INITSEG
sub dx,ax ! this will be SS after the move
move_self_1:
mov ds,ax
mov ax,#INITSEG ! real INITSEG
mov es,ax
seg cs
mov cx,setup_move_size
std ! we have to move up, so we use direction down
! because the areas may overlap
mov di,cx
dec di
mov si,di
sub cx,#move_self_here+0x200
rep
movsb
jmpi move_self_here,SETUPSEG ! jump to our final place
move_self_here:
mov cx,#move_self_here+0x200
rep
movsb
mov ax,#SETUPSEG
mov ds,ax
mov ss,dx
! now we are at the right place
end_move_self:
lidt idt_48 ! load idt with 0,0
lgdt gdt_48 ! load gdt with whatever appropriate
! that was painless, now we enable A20
call empty_8042
mov al,#0xD1 ! command write
out #0x64,al
call empty_8042
mov al,#0xDF ! A20 on
out #0x60,al
call empty_8042
! make sure any possible coprocessor is properly reset..
xor ax,ax
out #0xf0,al
call delay
out #0xf1,al
call delay
! well, that went ok, I hope. Now we have to reprogram the interrupts :-(
! we put them right after the intel-reserved hardware interrupts, at
! int 0x20-0x2F. There they won't mess up anything. Sadly IBM really
! messed this up with the original PC, and they haven't been able to
! rectify it afterwards. Thus the bios puts interrupts at 0x08-0x0f,
! which is used for the internal hardware interrupts as well. We just
! have to reprogram the 8259's, and it isn't fun.
mov al,#0x11 ! initialization sequence
out #0x20,al ! send it to 8259A-1
call delay
out #0xA0,al ! and to 8259A-2
call delay
mov al,#0x20 ! start of hardware int's (0x20)
out #0x21,al
call delay
mov al,#0x28 ! start of hardware int's 2 (0x28)
out #0xA1,al
call delay
mov al,#0x04 ! 8259-1 is master
out #0x21,al
call delay
mov al,#0x02 ! 8259-2 is slave
out #0xA1,al
call delay
mov al,#0x01 ! 8086 mode for both
out #0x21,al
call delay
out #0xA1,al
call delay
mov al,#0xFF ! mask off all interrupts for now
out #0xA1,al
call delay
mov al,#0xFB ! mask all irq's but irq2 which
out #0x21,al ! is cascaded
! Well, that certainly wasn't fun :-(. Hopefully it works, and we don't
! need no steenking BIOS anyway (except for the initial loading :-).
! The BIOS-routine wants lots of unnecessary data, and it's less
! "interesting" anyway. This is how REAL programmers do it.
!
! Well, now's the time to actually move into protected mode. To make
! things as simple as possible, we do no register set-up or anything,
! we let the gnu-compiled 32-bit programs do that. We just jump to
! absolute address 0x1000 (or the loader supplied one),
! in 32-bit protected mode.
!
! Note that the short jump isn't strictly needed, although there are
! reasons why it might be a good idea. It won't hurt in any case.
!
mov ax,#1 ! protected mode (PE) bit
lmsw ax ! This is it!
jmp flush_instr
flush_instr:
xor bx,bx ! Flag to indicate a boot
! NOTE: For high loaded big kernels we need a
! jmpi 0x100000,KERNEL_CS
!
! but we yet haven't reloaded the CS register, so the default size
! of the target offset still is 16 bit.
! However, using an operant prefix (0x66), the CPU will properly
! take our 48 bit far pointer. (INTeL 80386 Programmer's Reference
! Manual, Mixing 16-bit and 32-bit code, page 16-6)
db 0x66,0xea ! prefix + jmpi-opcode
code32: dd 0x1000 ! will be set to 0x100000 for big kernels
dw KERNEL_CS
kernel_version: .ascii UTS_RELEASE
.ascii " ("
.ascii LINUX_COMPILE_BY
.ascii "@"
.ascii LINUX_COMPILE_HOST
.ascii ") "
.ascii UTS_VERSION
db 0
! This is the default real mode switch routine.
! to be called just before protected mode transition
default_switch:
cli ! no interrupts allowed !
mov al,#0x80 ! disable NMI for the bootup sequence
out #0x70,al
retf
! This routine only gets called, if we get loaded by the simple
! bootsect loader _and_ have a bzImage to load.
! Because there is no place left in the 512 bytes of the boot sector,
! we must emigrate to code space here.
!
bootsect_helper:
seg cs
cmp word ptr bootsect_es,#0
jnz bootsect_second
seg cs
mov byte ptr type_of_loader,#0x20
mov ax,es
shr ax,#4
seg cs
mov byte ptr bootsect_src_base+2,ah
mov ax,es
seg cs
mov bootsect_es,ax
sub ax,#SYSSEG
retf ! nothing else to do for now
bootsect_second:
push cx
push si
push bx
test bx,bx ! 64K full ?
jne bootsect_ex
mov cx,#0x8000 ! full 64K move, INT15 moves words
push cs
pop es
mov si,#bootsect_gdt
mov ax,#0x8700
int 0x15
jc bootsect_panic ! this, if INT15 fails
seg cs
mov es,bootsect_es ! we reset es to always point to 0x10000
seg cs
inc byte ptr bootsect_dst_base+2
bootsect_ex:
seg cs
mov ah, byte ptr bootsect_dst_base+2
shl ah,4 ! we now have the number of moved frames in ax
xor al,al
pop bx
pop si
pop cx
retf
bootsect_gdt:
.word 0,0,0,0
.word 0,0,0,0
bootsect_src:
.word 0xffff
bootsect_src_base:
.byte 0,0,1 ! base = 0x010000
.byte 0x93 ! typbyte
.word 0 ! limit16,base24 =0
bootsect_dst:
.word 0xffff
bootsect_dst_base:
.byte 0,0,0x10 ! base = 0x100000
.byte 0x93 ! typbyte
.word 0 ! limit16,base24 =0
.word 0,0,0,0 ! BIOS CS
.word 0,0,0,0 ! BIOS DS
bootsect_es:
.word 0
bootsect_panic:
push cs
pop ds
cld
lea si,bootsect_panic_mess
call prtstr
bootsect_panic_loop:
jmp bootsect_panic_loop
bootsect_panic_mess:
.ascii "INT15 refuses to access high mem, giving up..."
db 0
! This routine checks that the keyboard command queue is empty
! (after emptying the output buffers)
!
! No timeout is used - if this hangs there is something wrong with
! the machine, and we probably couldn't proceed anyway.
empty_8042:
call delay
in al,#0x64 ! 8042 status port
test al,#1 ! output buffer?
jz no_output
call delay
in al,#0x60 ! read it
jmp empty_8042
no_output:
test al,#2 ! is input buffer full?
jnz empty_8042 ! yes - loop
ret
!
! Read the cmos clock. Return the seconds in al
!
gettime:
push cx
mov ah,#0x02
int 0x1a
mov al,dh ! dh contains the seconds
and al,#0x0f
mov ah,dh
mov cl,#0x04
shr ah,cl
aad
pop cx
ret
!
! Delay is needed after doing I/O
!
delay:
.word 0x00eb ! jmp $+2
ret
!
! Descriptor tables
!
gdt:
.word 0,0,0,0 ! dummy
.word 0,0,0,0 ! unused
.word 0xFFFF ! 4Gb - (0x100000*0x1000 = 4Gb)
.word 0x0000 ! base address=0
.word 0x9A00 ! code read/exec
.word 0x00CF ! granularity=4096, 386 (+5th nibble of limit)
.word 0xFFFF ! 4Gb - (0x100000*0x1000 = 4Gb)
.word 0x0000 ! base address=0
.word 0x9200 ! data read/write
.word 0x00CF ! granularity=4096, 386 (+5th nibble of limit)
idt_48:
.word 0 ! idt limit=0
.word 0,0 ! idt base=0L
gdt_48:
.word 0x800 ! gdt limit=2048, 256 GDT entries
.word 512+gdt,0x9 ! gdt base = 0X9xxxx
!
! Include video setup & detection code
!
#include "video.S"
!
! Setup signature -- must be last
!
setup_sig1: .word SIG1
setup_sig2: .word SIG2
!
! After this point, there is some free space which is used by the video mode
! handling code to store the temporary mode table (not used by the kernel).
!
modelist:
.text
endtext:
.data
enddata:
.bss
endbss: