mirror of
https://github.com/torvalds/linux.git
synced 2024-11-16 17:12:06 +00:00
575400d1b4
The EDD code would scan the command line as a fixed array, without taking account of either whitespace, null-termination, the old command-line protocol, late overrides early, or the fact that the command line may not be reachable from INITSEG. This should fix those problems, and enable us to use a longer command line. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Andi Kleen <ak@suse.de>
232 lines
7.2 KiB
ArmAsm
232 lines
7.2 KiB
ArmAsm
/*
|
|
* BIOS Enhanced Disk Drive support
|
|
* Copyright (C) 2002, 2003, 2004 Dell, Inc.
|
|
* by Matt Domsch <Matt_Domsch@dell.com> October 2002
|
|
* conformant to T13 Committee www.t13.org
|
|
* projects 1572D, 1484D, 1386D, 1226DT
|
|
* disk signature read by Matt Domsch <Matt_Domsch@dell.com>
|
|
* and Andrew Wilks <Andrew_Wilks@dell.com> September 2003, June 2004
|
|
* legacy CHS retrieval by Patrick J. LoPresti <patl@users.sourceforge.net>
|
|
* March 2004
|
|
* Command line option parsing, Matt Domsch, November 2004
|
|
*/
|
|
|
|
#include <linux/edd.h>
|
|
#include <asm/setup.h>
|
|
|
|
#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
|
|
|
|
# It is assumed that %ds == INITSEG here
|
|
|
|
movb $0, (EDD_MBR_SIG_NR_BUF)
|
|
movb $0, (EDDNR)
|
|
|
|
# Check the command line for options:
|
|
# edd=of disables EDD completely (edd=off)
|
|
# edd=sk skips the MBR test (edd=skipmbr)
|
|
# edd=on re-enables EDD (edd=on)
|
|
|
|
pushl %esi
|
|
movw $edd_mbr_sig_start, %di # Default to edd=on
|
|
|
|
movl %cs:(cmd_line_ptr), %esi
|
|
andl %esi, %esi
|
|
jz old_cl # Old boot protocol?
|
|
|
|
# Convert to a real-mode pointer in fs:si
|
|
movl %esi, %eax
|
|
shrl $4, %eax
|
|
movw %ax, %fs
|
|
andw $0xf, %si
|
|
jmp have_cl_pointer
|
|
|
|
# Old-style boot protocol?
|
|
old_cl:
|
|
push %ds # aka INITSEG
|
|
pop %fs
|
|
|
|
cmpw $0xa33f, (0x20)
|
|
jne done_cl # No command line at all?
|
|
movw (0x22), %si # Pointer relative to INITSEG
|
|
|
|
# fs:si has the pointer to the command line now
|
|
have_cl_pointer:
|
|
|
|
# Loop through kernel command line one byte at a time. Just in
|
|
# case the loader is buggy and failed to null-terminate the command line
|
|
# terminate if we get close enough to the end of the segment that we
|
|
# cannot fit "edd=XX"...
|
|
cl_atspace:
|
|
cmpw $-5, %si # Watch for segment wraparound
|
|
jae done_cl
|
|
movl %fs:(%si), %eax
|
|
andb %al, %al # End of line?
|
|
jz done_cl
|
|
cmpl $EDD_CL_EQUALS, %eax
|
|
jz found_edd_equals
|
|
cmpb $0x20, %al # <= space consider whitespace
|
|
ja cl_skipword
|
|
incw %si
|
|
jmp cl_atspace
|
|
|
|
cl_skipword:
|
|
cmpw $-5, %si # Watch for segment wraparound
|
|
jae done_cl
|
|
movb %fs:(%si), %al # End of string?
|
|
andb %al, %al
|
|
jz done_cl
|
|
cmpb $0x20, %al
|
|
jbe cl_atspace
|
|
incw %si
|
|
jmp cl_skipword
|
|
|
|
found_edd_equals:
|
|
# only looking at first two characters after equals
|
|
# late overrides early on the command line, so keep going after finding something
|
|
movw %fs:4(%si), %ax
|
|
cmpw $EDD_CL_OFF, %ax # edd=of
|
|
je do_edd_off
|
|
cmpw $EDD_CL_SKIP, %ax # edd=sk
|
|
je do_edd_skipmbr
|
|
cmpw $EDD_CL_ON, %ax # edd=on
|
|
je do_edd_on
|
|
jmp cl_skipword
|
|
do_edd_skipmbr:
|
|
movw $edd_start, %di
|
|
jmp cl_skipword
|
|
do_edd_off:
|
|
movw $edd_done, %di
|
|
jmp cl_skipword
|
|
do_edd_on:
|
|
movw $edd_mbr_sig_start, %di
|
|
jmp cl_skipword
|
|
|
|
done_cl:
|
|
popl %esi
|
|
jmpw *%di
|
|
|
|
# Read the first sector of each BIOS disk device and store the 4-byte signature
|
|
edd_mbr_sig_start:
|
|
movb $0x80, %dl # from device 80
|
|
movw $EDD_MBR_SIG_BUF, %bx # store buffer ptr in bx
|
|
edd_mbr_sig_read:
|
|
movl $0xFFFFFFFF, %eax
|
|
movl %eax, (%bx) # assume failure
|
|
pushw %bx
|
|
movb $READ_SECTORS, %ah
|
|
movb $1, %al # read 1 sector
|
|
movb $0, %dh # at head 0
|
|
movw $1, %cx # cylinder 0, sector 0
|
|
pushw %es
|
|
pushw %ds
|
|
popw %es
|
|
movw $EDDBUF, %bx # disk's data goes into EDDBUF
|
|
pushw %dx # work around buggy BIOSes
|
|
stc # work around buggy BIOSes
|
|
int $0x13
|
|
sti # work around buggy BIOSes
|
|
popw %dx
|
|
popw %es
|
|
popw %bx
|
|
jc edd_mbr_sig_done # on failure, we're done.
|
|
cmpb $0, %ah # some BIOSes do not set CF
|
|
jne edd_mbr_sig_done # on failure, we're done.
|
|
movl (EDDBUF+EDD_MBR_SIG_OFFSET), %eax # read sig out of the MBR
|
|
movl %eax, (%bx) # store success
|
|
incb (EDD_MBR_SIG_NR_BUF) # note that we stored something
|
|
incb %dl # increment to next device
|
|
addw $4, %bx # increment sig buffer ptr
|
|
cmpb $EDD_MBR_SIG_MAX, (EDD_MBR_SIG_NR_BUF) # Out of space?
|
|
jb edd_mbr_sig_read # keep looping
|
|
edd_mbr_sig_done:
|
|
|
|
# Do the BIOS Enhanced Disk Drive calls
|
|
# This consists of two calls:
|
|
# int 13h ah=41h "Check Extensions Present"
|
|
# int 13h ah=48h "Get Device Parameters"
|
|
# int 13h ah=08h "Legacy Get Device Parameters"
|
|
#
|
|
# A buffer of size EDDMAXNR*(EDDEXTSIZE+EDDPARMSIZE) is reserved for our use
|
|
# in the boot_params at EDDBUF. The first four bytes of which are
|
|
# used to store the device number, interface support map and version
|
|
# results from fn41. The next four bytes are used to store the legacy
|
|
# cylinders, heads, and sectors from fn08. The following 74 bytes are used to
|
|
# store the results from fn48. Starting from device 80h, fn41, then fn48
|
|
# are called and their results stored in EDDBUF+n*(EDDEXTSIZE+EDDPARMIZE).
|
|
# Then the pointer is incremented to store the data for the next call.
|
|
# This repeats until either a device doesn't exist, or until EDDMAXNR
|
|
# devices have been stored.
|
|
# The one tricky part is that ds:si always points EDDEXTSIZE bytes into
|
|
# the structure, and the fn41 and fn08 results are stored at offsets
|
|
# from there. This removes the need to increment the pointer for
|
|
# every store, and leaves it ready for the fn48 call.
|
|
# A second one-byte buffer, EDDNR, in the boot_params stores
|
|
# the number of BIOS devices which exist, up to EDDMAXNR.
|
|
# In setup.c, copy_edd() stores both boot_params buffers away
|
|
# for later use, as they would get overwritten otherwise.
|
|
# This code is sensitive to the size of the structs in edd.h
|
|
edd_start:
|
|
# %ds points to the bootsector
|
|
# result buffer for fn48
|
|
movw $EDDBUF+EDDEXTSIZE, %si # in ds:si, fn41 results
|
|
# kept just before that
|
|
movb $0x80, %dl # BIOS device 0x80
|
|
|
|
edd_check_ext:
|
|
movb $CHECKEXTENSIONSPRESENT, %ah # Function 41
|
|
movw $EDDMAGIC1, %bx # magic
|
|
int $0x13 # make the call
|
|
jc edd_done # no more BIOS devices
|
|
|
|
cmpw $EDDMAGIC2, %bx # is magic right?
|
|
jne edd_next # nope, next...
|
|
|
|
movb %dl, %ds:-8(%si) # store device number
|
|
movb %ah, %ds:-7(%si) # store version
|
|
movw %cx, %ds:-6(%si) # store extensions
|
|
incb (EDDNR) # note that we stored something
|
|
|
|
edd_get_device_params:
|
|
movw $EDDPARMSIZE, %ds:(%si) # put size
|
|
movw $0x0, %ds:2(%si) # work around buggy BIOSes
|
|
movb $GETDEVICEPARAMETERS, %ah # Function 48
|
|
int $0x13 # make the call
|
|
# Don't check for fail return
|
|
# it doesn't matter.
|
|
edd_get_legacy_chs:
|
|
xorw %ax, %ax
|
|
movw %ax, %ds:-4(%si)
|
|
movw %ax, %ds:-2(%si)
|
|
# Ralf Brown's Interrupt List says to set ES:DI to
|
|
# 0000h:0000h "to guard against BIOS bugs"
|
|
pushw %es
|
|
movw %ax, %es
|
|
movw %ax, %di
|
|
pushw %dx # legacy call clobbers %dl
|
|
movb $LEGACYGETDEVICEPARAMETERS, %ah # Function 08
|
|
int $0x13 # make the call
|
|
jc edd_legacy_done # failed
|
|
movb %cl, %al # Low 6 bits are max
|
|
andb $0x3F, %al # sector number
|
|
movb %al, %ds:-1(%si) # Record max sect
|
|
movb %dh, %ds:-2(%si) # Record max head number
|
|
movb %ch, %al # Low 8 bits of max cyl
|
|
shr $6, %cl
|
|
movb %cl, %ah # High 2 bits of max cyl
|
|
movw %ax, %ds:-4(%si)
|
|
|
|
edd_legacy_done:
|
|
popw %dx
|
|
popw %es
|
|
movw %si, %ax # increment si
|
|
addw $EDDPARMSIZE+EDDEXTSIZE, %ax
|
|
movw %ax, %si
|
|
|
|
edd_next:
|
|
incb %dl # increment to next device
|
|
cmpb $EDDMAXNR, (EDDNR) # Out of space?
|
|
jb edd_check_ext # keep looping
|
|
|
|
edd_done:
|
|
#endif
|