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| author | H. Peter Anvin <hpa@zytor.com> | 2009-08-02 11:56:38 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2009-08-02 11:56:38 -0700 |
| commit | 32598725b8d1941899bc700b5d71efa57c3f419c (patch) | |
| tree | f33351743469b23683c69bbd416783c3f1cb7b36 | |
| parent | d655fa0bc3a9d817df253d4f67bb92da20ef741a (diff) | |
| download | syslinux-32598725b8d1941899bc700b5d71efa57c3f419c.tar.gz | |
memdisk: don't set CX:DX for INT 13h AH=15h for floppies
Win98SE DOS apparently hangs if INT 13h, AH=15h returns the capacity
in CX:DX for floppies... *unless* EDD is enabled. Confused yet?
This patch also adds some more tracing framework.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| -rw-r--r-- | memdisk/memdisk.inc | 55 | ||||
| -rw-r--r-- | memdisk/setup.c | 4 |
2 files changed, 54 insertions, 5 deletions
diff --git a/memdisk/memdisk.inc b/memdisk/memdisk.inc index c7eb9f1a..f4cb0fe6 100644 --- a/memdisk/memdisk.inc +++ b/memdisk/memdisk.inc @@ -27,11 +27,47 @@ call debug_tracer db %1 %endmacro +%macro WRITEHEX2 0-1 al +%ifnidni %1,al + push ax + mov al,%1 + call writehex2 + pop ax +%else + call writehex2 +%endif +%endmacro +%macro WRITEHEX4 0-1 ax +%ifnidni %1,ax + push ax + mov ax,%1 + call writehex4 + pop ax +%else + call writehex4 +%endif +%endmacro +%macro WRITEHEX8 0-1 eax +%ifnidni %1,eax + push eax + mov eax,%1 + call writehex8 + pop eax +%else + call writehex8 +%endif +%endmacro %else ; DEBUG_TRACERS %macro TRACER 1 %endmacro +%macro WRITEHEX2 0-1 +%endmacro +%macro WRITEHEX4 0-1 +%endmacro +%macro WRITEHEX8 0-1 +%endmacro %endif ; DEBUG_TRACERS @@ -90,7 +126,7 @@ Pointers: dw Int13Start IretPtr equ Int13Start.iret Int13Start: cmp word [cs:Recursive],0 - jne jmp_oldint13 + jne recursive ; Swap stack mov [cs:Stack],esp @@ -113,7 +149,15 @@ Int13Start: jb .nomatch ; Drive < Our drive dec dl ; Drive > Our drive, adjust drive # .nomatch: +%ifdef DEBUG_TRACERS + TRACER '!' + WRITEHEX2 dl + TRACER ',' + mov ax,[cs:SavedAX] + WRITEHEX4 +%else mov ax,[cs:SavedAX] +%endif inc word [cs:Recursive] pushf call far [cs:OldInt13] @@ -141,6 +185,8 @@ Int13Start: lss esp,[cs:Stack] .iret: iret +recursive: + TRACER '@' jmp_oldint13: jmp far [cs:OldInt13] @@ -154,6 +200,7 @@ our_drive: pushad mov bp,sp ; Point BP to the entry stack frame TRACER 'F' + WRITEHEX4 ; Note: AX == P_AX here cmp ah,Int13FuncsCnt-1 ja Invalid_jump @@ -227,13 +274,15 @@ GetDriveType: test byte [DriveNo],80h mov bl,02h ; Type 02h = floppy with changeline jz .floppy - ; Hard disks only... + ; Hard disks only! DO NOT set CX:DX for floppies... + ; it apparently causes Win98SE DOS to go into an loop + ; resetting the drive over and over. Sigh. inc bx ; Type = 03h -.floppy: mov dx,[DiskSize] ; Return the disk size in sectors mov P_DX,dx mov cx,[DiskSize+2] mov P_CX,cx +.floppy: mov P_AH,bl ; 02h floppy, 03h hard disk pop ax ; Drop return address xor ax,ax ; Success... diff --git a/memdisk/setup.c b/memdisk/setup.c index 013f3dfa..caee377a 100644 --- a/memdisk/setup.c +++ b/memdisk/setup.c @@ -90,7 +90,7 @@ struct edd_dpt { uint64_t devpath[2]; /* Device path (double QuadWord!) */ uint8_t res3; /* Reserved */ uint8_t chksum; /* DPI checksum */ -}; +} __attribute__((packed)); struct patch_area { uint32_t diskbuf; @@ -131,7 +131,7 @@ struct patch_area { dpt_t dpt; struct edd_dpt edd_dpt; -}; +} __attribute__((packed)); /* Access to high memory */ |