MEMDISK: Default to floppy = EDD off, hard disk = EDD on, give option

Default to having EDD off on floppies and EDD on on hard disks.
Additionally, add options "edd" and "noedd" to force this choice.

3 files changed, 31 insertions, 9 deletions

diff --git a/memdisk/memdisk.asm b/memdisk/memdisk.asm
index 09055d8f..1d3d39de 100644
--- a/memdisk/memdisk.asm
+++ b/memdisk/memdisk.asm
@@ -6,7 +6,7 @@
 ;  A program to emulate an INT 13h disk BIOS from a "disk" in extended
 ;  memory.
 ;
-;   Copyright (C) 2001-2006  H. Peter Anvin
+;   Copyright (C) 2001-2007  H. Peter Anvin
 ;
 ;  This program is free software; you can redistribute it and/or modify
 ;  it under the terms of the GNU General Public License as published by
@@ -152,8 +152,8 @@ Int13Start:
 		mov bp,sp		; Point BP to the entry stack frame
 		TRACER 'F'
 		; Note: AH == P_AH here
-		cmp ah,Int13FuncsMax
-		jae Invalid_jump
+		cmp ah,[Int13MaxFunc]
+		ja Invalid_jump
 		xor al,al		; AL = 0 is standard entry condition
 		mov di,ax
 		shr di,7		; Convert AH to an offset in DI
@@ -870,7 +870,7 @@ Int13Funcs	dw Reset		; 00h - RESET
 %endif
 
 Int13FuncsEnd	equ $
-Int13FuncsMax	equ (Int13FuncsEnd-Int13Funcs) >> 1
+Int13FuncsCnt	equ (Int13FuncsEnd-Int13Funcs) >> 1
 
 %if EDD
 EDD_DPT:
@@ -933,8 +933,9 @@ OldInt15	dd 0			; INT 15h in chain
 OldDosMem	dw 0			; Old position of DOS mem end
 BootLoaderID	db 0			; Boot loader ID from header
 ; ---- MDI structure ends here ---
-		db 0, 0, 0		; pad
+Int13MaxFunc	db Int13FuncsCnt-1	; Max INT 13h function (to disable EDD)
 
+		db 0, 0			; pad
 MemInt1588	dw 0			; 1MB-65MB memory amount (1K)
 
 Cylinders	dw 0			; Cylinder count
diff --git a/memdisk/memdisk.doc b/memdisk/memdisk.doc
index fdcc259e..759a7b27 100644
--- a/memdisk/memdisk.doc
+++ b/memdisk/memdisk.doc
@@ -89,6 +89,12 @@ d) MEMDISK normally uses the BIOS "INT 15h mover" API to access high
    safeint	Use INT 15h access to protected memory, but invoke
 		INT 15h the way it was *before* MEMDISK was loaded.
 
+e) MEMDISK by default supports EDD/EBIOS on hard disks, but not on
+   floppy disks.  This can be controlled with the options:
+
+   edd		Enable EDD/EBIOS
+   noedd	Disable EDD/EBIOS
+
 
 Some interesting things to note:
 
@@ -136,7 +142,7 @@ http://www.ctyme.com/rbrown.htm, for a detailed description.
 
 The MEMDISK info structure currently contains:
 
-	[ES:DI]		word	Total size of structure (currently 27 bytes)
+	[ES:DI]		word	Total size of structure (currently 28 bytes)
 	[ES:DI+2]	byte	MEMDISK minor version
 	[ES:DI+3]	byte	MEMDISK major version
 	[ES:DI+4]	dword	Pointer to MEMDISK data in high memory
diff --git a/memdisk/setup.c b/memdisk/setup.c
index 8c83f039..70dc1d65 100644
--- a/memdisk/setup.c
+++ b/memdisk/setup.c
@@ -70,8 +70,10 @@ struct patch_area {
 
   uint16_t olddosmem;
   uint8_t  bootloaderid;
+  uint8_t  maxint13func;
+#define MAXINT13_NOEDD	0x16
 
-  uint8_t  _pad[3];
+  uint8_t  _pad[2];
   uint16_t memint1588;
 
   uint16_t cylinders;
@@ -552,6 +554,7 @@ void setup(syscall_t cs_syscall, void *cs_bounce)
   com32sys_t regs;
   uint32_t ramdisk_image, ramdisk_size;
   int bios_drives;
+  int do_edd = -1;		/* -1 = default, 0 = no, 1 = yes */
 
   /* Set up global variables */
   syscall = cs_syscall;
@@ -579,11 +582,19 @@ void setup(syscall_t cs_syscall, void *cs_bounce)
 
   geometry = get_disk_image_geometry(ramdisk_image, ramdisk_size);
 
-  printf("Disk is %s %d, %u K, C/H/S = %u/%u/%u\n",
+  if (getcmditem("edd") != CMD_NOTFOUND)
+    do_edd = 1;
+  else if (getcmditem("noedd") != CMD_NOTFOUND)
+    do_edd = 0;
+  else
+    do_edd = (geometry->driveno & 0x80) ? 1 : 0;
+
+  printf("Disk is %s %d, %u K, C/H/S = %u/%u/%u, EDD %s\n",
 	 (geometry->driveno & 0x80) ? "hard disk" : "floppy",
 	 geometry->driveno & 0x7f,
 	 geometry->sectors >> 1,
-	 geometry->c, geometry->h, geometry->s);
+	 geometry->c, geometry->h, geometry->s,
+	 do_edd ? "on" : "off");
 
   /* Reserve the ramdisk memory */
   insertrange(ramdisk_image, ramdisk_size, 2);
@@ -633,6 +644,10 @@ void setup(syscall_t cs_syscall, void *cs_bounce)
     pptr->configflags |= CONFIG_BIGRAW|CONFIG_RAW;
   }
 
+  /* pptr->maxint13func defaults to EDD enabled, if compiled in */
+  if (!do_edd)
+    pptr->maxint13func = MAXINT13_NOEDD;
+
   /* Set up a drive parameter table */
   if ( geometry->driveno & 0x80 ) {
     /* Hard disk */