1 ; -*- fundamental -*- (asm-mode sucks)
2 ; ****************************************************************************
6 ; A program to emulate an INT 13h disk BIOS from a "disk" in extended
9 ; Copyright 2001-2009 H. Peter Anvin - All Rights Reserved
10 ; Copyright 2009 Intel Corporation; author: H. Peter Anvin
12 ; This program is free software; you can redistribute it and/or modify
13 ; it under the terms of the GNU General Public License as published by
14 ; the Free Software Foundation, Inc., 53 Temple Place Ste 330,
15 ; Boston MA 02111-1307, USA; either version 2 of the License, or
16 ; (at your option) any later version; incorporated herein by reference.
18 ; ****************************************************************************
21 %include "../version.gen"
24 ; %define DEBUG_TRACERS ; Uncomment to get debugging tracers
38 %endif ; DEBUG_TRACERS
40 ; Flags we test our configuration against
41 %define CONFIG_READONLY 0x01
42 %define CONFIG_RAW 0x02
43 %define CONFIG_SAFEINT 0x04
44 %define CONFIG_BIGRAW 0x08 ; MUST be 8!
48 %define SECTORSIZE_LG2 9 ; log2(sector size)
49 %define SECTORSIZE (1 << SECTORSIZE_LG2)
51 ; Parameter registers definition; this is the definition
53 %define P_DS word [bp+34]
54 %define P_ES word [bp+32]
55 %define P_EAX dword [bp+28]
56 %define P_HAX word [bp+30]
57 %define P_AX word [bp+28]
58 %define P_AL byte [bp+28]
59 %define P_AH byte [bp+29]
60 %define P_ECX dword [bp+24]
61 %define P_HCX word [bp+26]
62 %define P_CX word [bp+24]
63 %define P_CL byte [bp+24]
64 %define P_CH byte [bp+25]
65 %define P_EDX dword [bp+20]
66 %define P_HDX word [bp+22]
67 %define P_DX word [bp+20]
68 %define P_DL byte [bp+20]
69 %define P_DH byte [bp+21]
70 %define P_EBX dword [bp+16]
71 %define P_HBX word [bp+18]
72 %define P_HBXL byte [bp+18]
73 %define P_BX word [bp+16]
74 %define P_BL byte [bp+16]
75 %define P_BH byte [bp+17]
76 %define P_EBP dword [bp+8]
77 %define P_BP word [bp+8]
78 %define P_ESI dword [bp+4]
79 %define P_SI word [bp+4]
80 %define P_EDI dword [bp]
81 %define P_DI word [bp]
84 ; These pointers are used by the installer and
85 ; must be first in the binary
86 Pointers: dw Int13Start
92 IretPtr equ Int13Start.iret
103 ; See if DL points to our class of device (FD, HD)
108 js .nomatch ; If SF=0, we have a class match here
109 ; 0x00 the sign bit for FD
110 ; 0x80 the sign bit for HD
111 jz .our_drive ; If ZF=1, we have an exact match
113 jb .nomatch ; Drive < Our drive
114 dec dl ; Drive > Our drive, adjust drive #
118 call far [cs:OldInt13]
122 cmp byte [cs:SavedAX+1],08h ; Get drive params function?
124 cmp byte [cs:SavedAX+1],15h ; Get disk type function?
126 test byte [bp+4],80h ; Hard disk?
128 .restoredl: ; DL should have number of drives
134 mov ax,[bp+2] ; Flags
136 mov [bx+4],al ; Arithmetic flags
145 ; Set up standard entry frame
152 mov bp,sp ; Point BP to the entry stack frame
154 ; Note: AH == P_AH here
155 cmp ah,Int13FuncsCnt-1
157 xor al,al ; AL = 0 is standard entry condition
159 shr di,7 ; Convert AH to an offset in DI
162 Done: ; Standard routine for return
169 mov [es:bx],ah ; Save status
173 ; This sets the low byte (the arithmetic flags) of the
174 ; FLAGS on stack to either 00h (no flags) or 01h (CF)
175 ; depending on if AH was zero or not.
176 setnz [bx+4] ; Set CF iff error
184 ; Reset affects multiple drives, so we need to pass it on
186 xor ax,ax ; Bottom of memory
188 test dl,dl ; Always pass it on if we are
190 js .hard_disk ; Bit 7 set
191 ; Some BIOSes get very unhappy if we pass a reset floppy
192 ; command to them and don't actually have any floppies.
193 ; This is a bug, but we have to deal with it nontheless.
194 ; Therefore, if we are the *ONLY* floppy drive, and the
195 ; user didn't request HD reset, then just drop the command.
196 ; BIOS equipment byte, top two bits + 1 == total # of floppies
197 test byte [es:0x410],0C0h
199 jmp .pass_on ; ... otherwise pass it to the BIOS
201 ; ... same thing for hard disks, sigh ...
202 cmp byte [es:0x475],1 ; BIOS variable for number of hard
207 pop ax ; Drop return address
208 popad ; Restore all registers
211 lss esp,[cs:Stack] ; Restore the stack
212 and dl,80h ; Clear all but the type bit
213 jmp far [cs:OldInt13]
217 pop dx ; Drop return address
220 mov ah,01h ; Unsupported function
224 test byte [DriveNo],80h
225 mov bl,02h ; Type 02h = floppy with changeline
229 mov dx,[DiskSize] ; Return the disk size in sectors
234 mov P_AH,bl ; 02h floppy, 03h hard disk
235 pop ax ; Drop return address
236 xor ax,ax ; Success...
237 jmp DoneWeird ; But don't stick it into P_AX
243 mov ah,[bx] ; Copy last status
255 movzx ax,P_AL ; AH = 0, AL = transfer count
262 test byte [ConfigFlags],CONFIG_READONLY
265 xchg esi,edi ; Opposite direction of a Read!
267 .readonly: mov ah,03h ; Write protected medium
270 ; Verify integrity; just bounds-check
273 call setup_regs ; Returns error if appropriate
274 ; And fall through to success
276 CheckIfReady: ; These are always-successful noop functions
284 xor ax,ax ; Always successful
289 mov dl,[DriveCnt] ; Cached data
291 test byte [DriveNo],80h
299 dec ax ; We report the highest #, not the count
309 ; Is this MEMDISK installation check?
320 ; MEMDISK installation check...
326 mov P_DI,MemDisk_Info
332 ; EDD functions -- only if enabled
341 mov P_BX,0AA55h ; EDD signature
342 mov P_AX,03000h ; EDD 3.0
343 mov P_CX,0003h ; Bit 0 - Fixed disk access subset
344 ; Bit 1 - Locking and ejecting subset
345 pop ax ; Drop return address
347 jmp DoneWeird ; Success, but AH != 0, sigh...
363 xchg esi,edi ; Opposite direction of a Read!
370 call edd_setup_regs ; Just bounds checking
382 lodsw ; Length of our DPT
384 cmp cx,26 ; Minimum size
406 ; Set up registers as for a "Read", and compares against disk
408 ; WARNING: This fails immediately, even if we can transfer some
409 ; sectors. This isn't really the correct behaviour.
412 ; Convert a CHS address in P_CX/P_DH into an LBA in eax
414 ; CL[0:5] = sector (1-based) CL[7:6] = cyl[9:8]
417 movzx ebx,cl ; Sector number
419 dec ebx ; Sector number is 1-based
422 movzx edi,P_DH ; Head number
423 movzx eax,word [Heads]
427 xchg cl,ch ; Now (E)CX <- cylinder number
428 mul ecx ; eax <- Heads*cyl# (edx <- 0)
432 ; Now eax = LBA, edx = 0
435 ; setup_regs continues...
437 ; Note: edi[31:16] and ecx[31:16] = 0 already
438 mov di,P_BX ; Get linear address of target buffer
441 add edi,ecx ; EDI = address to fetch to
442 movzx ecx,P_AL ; Sector count
444 add eax,ecx ; LBA of final sector + 1
445 shl esi,SECTORSIZE_LG2 ; LBA -> byte offset
446 add esi,[DiskBuf] ; Get address in high memory
447 cmp eax,[DiskSize] ; Check the high mark against limit
449 shl ecx,SECTORSIZE_LG2-2 ; Convert count to dwords
452 .overrun: pop ax ; Drop setup_regs return address
453 mov ax,0200h ; Missing address mark
456 ; Set up registers as for an EDD Read, and compares against disk size.
460 mov si,P_SI ; DS:SI -> DAPA
467 cmp dword [es:si+4],-1
470 movzx ebx,word [es:si+4] ; Offset
471 movzx edi,word [es:si+6] ; Segment
477 cmp dx,24 ; Must be large enough to hold
481 cmp dword [es:si+20],0 ; > 4 GB addresses not supported
482 mov ax,0900h ; "Data boundary error" - bogus, but
483 ; no really better code available
489 cmp dword [es:si+12],0 ; LBA too large?
492 movzx ecx, word [es:si+2] ; Sectors to transfer
493 mov esi,[es:si+8] ; Starting sector
500 shl ecx,SECTORSIZE_LG2-2 ; Convert to dwords
501 shl esi,SECTORSIZE_LG2 ; Convert to an offset
508 mov ax,0100h ; Invalid command
510 pop ax ; Drop setup_regs return address
514 mov ax,0200h ; "Address mark not found" =
515 ; LBA beyond end of disk
517 and word [es:si+2],0 ; No sectors transferred
523 mov ax,0B200h ; Volume Not Removable
530 ; INT 15h intercept routines
533 cmp edx,534D4150h ; "SMAP"
535 cmp ecx,20 ; Need 20 bytes
545 add bx,16 ; Advance to next
546 mov eax,[bx-8] ; Type
547 and eax,eax ; Null type?
548 jz .renew ; If so advance to next
553 mov eax,[bx-4] ; Extended attributes
555 mov ecx,24 ; Bytes loaded
557 mov eax,[bx-16] ; Start addr (low)
558 mov edx,[bx-12] ; Start addr (high)
561 mov eax,[bx] ; End addr (low)
562 mov edx,[bx+4] ; End addr (high)
563 sub eax,[bx-16] ; Derive the length
565 mov [es:di+8],eax ; Length (low)
566 mov [es:di+12],edx ; Length (high)
567 cmp dword [bx+8],-1 ; Type of next = end?
569 xor ebx,ebx ; Done with table
572 mov edx,eax ; Some systems expect eax = edx = SMAP
575 mov byte [bp+6], 02h ; Clear CF
580 mov byte [bp+6], 03h ; Set CF
597 jmp far [cs:OldInt15]
599 int15_e801: ; Get mem size for > 64 MB config
604 jmp short int15_success
606 int15_e881: ; Get mem size for > 64 MB config
612 jmp short int15_success
614 int15_88: ; Get extended mem size
615 mov ax,[cs:MemInt1588]
616 jmp short int15_success
619 ; Routine to copy in/out of high memory
620 ; esi = linear source address
621 ; edi = linear target address
622 ; ecx = 32-bit word count
624 ; Assumes cs = ds = es
632 mov bx, real_int15_stub
634 test byte [ConfigFlags], CONFIG_RAW|CONFIG_SAFEINT
635 jz .anymode ; Always do the real INT 15h
637 smsw ax ; Unprivileged!
639 jnz .protmode ; Protmode -> do real INT 15h
642 ; Raw or Safeint mode, and we're in real mode...
644 test byte [ConfigFlags], CONFIG_SAFEINT
649 ; We're in real mode, do it outselves
664 ; Test to see if A20 is enabled or not
681 push dx ; <D> Save A20 status
684 mov ax,2401h ; Enable A20
690 ; DX = 16 for BIGRAW, 8 for RAW
691 ; 8 is selector for a 64K flat segment,
692 ; 16 is selector for a 4GB flat segment.
699 mov bx,16 ; Large flat segment
705 ; DX has the appropriate value to put in
706 ; the registers on return
713 pop dx ; <D> A20 status
719 mov ax,2400h ; Disable A20
726 ; We're in real mode with CONFIG_SAFEINT, invoke the
727 ; original INT 15h vector. We used to test for the
728 ; INT 15h vector being unchanged here, but that is
729 ; *us*; however, the test was wrong for years (always
730 ; negative) so instead of fixing the test do what we
731 ; tested and don't bother probing.
732 mov bx, fake_int15_stub
746 push ecx ; Transfer size this cycle
750 mov [Mover_src1+2], al
755 mov [Mover_dst1+2], al
759 shl cx,1 ; Convert to 16-bit words
760 call bx ; INT 15h stub
761 pop eax ; Transfer size this cycle
781 cli ; Some BIOSes enable interrupts on INT 15h
807 Int13Funcs dw Reset ; 00h - RESET
808 dw GetStatus ; 01h - GET STATUS
810 dw Write ; 03h - WRITE
811 dw Verify ; 04h - VERIFY
812 dw Invalid ; 05h - FORMAT TRACK
813 dw Invalid ; 06h - FORMAT TRACK AND SET BAD FLAGS
814 dw Invalid ; 07h - FORMAT DRIVE AT TRACK
815 dw GetParms ; 08h - GET PARAMETERS
816 dw InitWithParms ; 09h - INITIALIZE CONTROLLER WITH
820 dw Seek ; 0Ch - SEEK TO CYLINDER
821 dw Reset ; 0Dh - RESET HARD DISKS
824 dw CheckIfReady ; 10h - CHECK IF READY
825 dw Recalibrate ; 11h - RECALIBRATE
829 dw GetDriveType ; 15h - GET DRIVE TYPE
830 dw DetectChange ; 16h - DETECT DRIVE CHANGE
842 dw ReadMult ; 21h - READ MULTIPLE
843 dw WriteMult ; 22h - WRITE MULTIPLE
844 dw SetMode ; 23h - SET CONTROLLER FEATURES
845 dw SetMode ; 24h - SET MULTIPLE MODE
846 dw Invalid ; 25h - IDENTIFY DRIVE
874 dw EDDPresence ; 41h - EDD PRESENCE DETECT
875 dw EDDRead ; 42h - EDD READ
876 dw EDDWrite ; 43h - EDD WRITE
877 dw EDDVerify ; 44h - EDD VERIFY
878 dw EDDLock ; 45h - EDD LOCK/UNLOCK MEDIA
879 dw EDDEject ; 46h - EDD EJECT
880 dw EDDSeek ; 47h - EDD SEEK
881 dw EDDGetParms ; 48h - EDD GET PARAMETERS
882 dw EDDDetectChange ; 49h - EDD MEDIA CHANGE STATUS
886 Int13FuncsCnt equ (Int13FuncsEnd-Int13Funcs) >> 1
890 Shaker dw ShakerEnd-$-1 ; Descriptor table limit
891 dd 0 ; Pointer to self
894 Shaker_RMDS: dd 0x0000ffff ; 64K data segment
897 Shaker_DS: dd 0x0000ffff ; 4GB data segment
904 Mover dd 0, 0, 0, 0 ; Must be zero
905 dw 0ffffh ; 64 K segment size
906 Mover_src1: db 0, 0, 0 ; Low 24 bits of source addy
907 db 93h ; Access rights
908 db 00h ; Extended access rights
909 Mover_src2: db 0 ; High 8 bits of source addy
910 dw 0ffffh ; 64 K segment size
911 Mover_dst1: db 0, 0, 0 ; Low 24 bits of target addy
912 db 93h ; Access rights
913 db 00h ; Extended access rights
914 Mover_dst2: db 0 ; High 8 bits of source addy
915 Mover_dummy2: dd 0, 0, 0, 0 ; More space for the BIOS
918 MemDisk_Info equ $ ; Pointed to by installation check
919 MDI_Bytes dw MDI_Len ; Total bytes in MDI structure
920 MDI_Version db VERSION_MINOR, VERSION_MAJOR ; MEMDISK version
922 PatchArea equ $ ; This gets filled in by the installer
924 DiskBuf dd 0 ; Linear address of high memory disk
925 DiskSize dd 0 ; Size of disk in blocks
926 CommandLine dw 0, 0 ; Far pointer to saved command line
928 OldInt13 dd 0 ; INT 13h in chain
929 OldInt15 dd 0 ; INT 15h in chain
931 OldDosMem dw 0 ; Old position of DOS mem end
932 BootLoaderID db 0 ; Boot loader ID from header
935 DPT_ptr dw 0 ; If nonzero, pointer to DPT
936 ; Original DPT pointer follows
938 MDI_Len equ $-MemDisk_Info
940 ; ---- MDI structure ends here ---
941 MemInt1588 dw 0 ; 1MB-65MB memory amount (1K)
943 Cylinders dw 0 ; Cylinder count
944 Heads dw 0 ; Head count
945 Sectors dd 0 ; Sector count (zero-extended)
947 Mem1MB dd 0 ; 1MB-16MB memory amount (1K)
948 Mem16MB dd 0 ; 16MB-4G memory amount (64K)
950 DriveNo db 0 ; Our drive number
951 DriveType db 0 ; Our drive type (floppies)
952 DriveCnt db 0 ; Drive count (from the BIOS)
954 ConfigFlags db 0 ; Bit 0 - readonly
956 MyStack dw 0 ; Offset of stack
957 StatusPtr dw 0 ; Where to save status (zeroseg ptr)
959 DPT times 16 db 0 ; BIOS parameter table pointer (floppies)
960 OldInt1E dd 0 ; Previous INT 1E pointer (DPT)
966 ; Bit 0 - DMA boundaries handled transparently
967 ; Bit 3 - Device supports write verify
968 ; Bit 5 - Media is lockable
969 .cylinders dd 0 ; Filled in by installer
970 .heads dd 0 ; Filled in by installer
971 .sectors dd 0 ; Filled in by installer
972 .totalsize dd 0, 0 ; Filled in by installer
973 .bytespersec dw SECTORSIZE
974 .eddtable dw -1, -1 ; Invalid DPTE pointer
979 Stack dd 0 ; Saved SS:ESP on invocation
981 SavedAX dw 0 ; AX saved on invocation
983 alignb 4, db 0 ; We *MUST* end on a dword boundary
985 E820Table equ $ ; The installer loads the E820 table here
986 TotalSize equ $ ; End pointer