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authorH. Peter Anvin <hpa@zytor.com>2007-09-21 16:24:35 -0700
committerH. Peter Anvin <hpa@zytor.com>2007-09-21 16:24:35 -0700
commit8dabb2ab591ccaf0721ddf4e81ff8d0b5fa2ff4d (patch)
treed93e3855613bc7aa69224efd216aeb43022429ae /memdisk
parent426d986dbc77abf2247b08c44c18bf9a478c2e8e (diff)
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memdisk: add "nopass" option to completely take over INT 13h
Add the "nopass" option to completely remove the system drives. This is a pretty big hammer and is largely for debugging at this stage; it probably needs more polishing before it can be made official.
Diffstat (limited to 'memdisk')
-rw-r--r--memdisk/memdisk.asm4
-rw-r--r--memdisk/setup.c70
2 files changed, 43 insertions, 31 deletions
diff --git a/memdisk/memdisk.asm b/memdisk/memdisk.asm
index a1713802..1e27e1e9 100644
--- a/memdisk/memdisk.asm
+++ b/memdisk/memdisk.asm
@@ -91,7 +91,9 @@ Pointers: dw Int13Start
dw Int15Start
dw PatchArea
dw TotalSize
+ dw IretPtr
+IretPtr equ Int13Start.iret
Int13Start:
; Swap stack
mov [cs:Stack],esp
@@ -139,7 +141,7 @@ Int13Start:
pop ax
pop bp
lss esp,[cs:Stack]
- iret
+.iret: iret
.our_drive:
; Set up standard entry frame
diff --git a/memdisk/setup.c b/memdisk/setup.c
index bacaba4d..bffaf7a8 100644
--- a/memdisk/setup.c
+++ b/memdisk/setup.c
@@ -1,6 +1,6 @@
/* ----------------------------------------------------------------------- *
*
- * Copyright 2001-2006 H. Peter Anvin - All Rights Reserved
+ * Copyright 2001-2007 H. Peter Anvin - All Rights Reserved
*
* 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
@@ -29,6 +29,7 @@ struct memdisk_header {
uint16_t int15_offs;
uint16_t patch_offs;
uint16_t total_size;
+ uint16_t iret_offs;
};
/* The Disk Parameter Table may be required */
@@ -762,37 +763,46 @@ void setup(syscall_t cs_syscall, void *cs_bounce)
ranges[--nranges].type = -1;
}
- /* Query drive parameters of this type */
- memset(&regs, 0, sizeof regs);
- regs.es = 0;
- regs.eax.b[1] = 0x08;
- regs.edx.b[0] = geometry->driveno & 0x80;
- syscall(0x13, &regs, &regs);
-
- if ( regs.eflags.l & 1 ) {
- printf("INT 13 08: Failure, assuming this is the only drive\n");
+ if (getcmditem("nopass") != CMD_NOTFOUND) {
+ /* nopass specified - we're the only drive by definition */
+ printf("nopass specified - we're the only drive\n");
+ bios_drives = 0;
pptr->drivecnt = 0;
+ pptr->oldint13 = driverptr+hptr->iret_offs;
} else {
- printf("INT 13 08: Success, count = %u, BPT = %04x:%04x\n",
- regs.edx.b[0], regs.es, regs.edi.w[0]);
- pptr->drivecnt = regs.edx.b[0];
- }
-
- /* Compare what INT 13h returned with the appropriate equipment byte */
- if ( geometry->driveno & 0x80 ) {
- bios_drives = rdz_8(BIOS_HD_COUNT);
- } else {
- uint8_t equip = rdz_8(BIOS_EQUIP);
-
- if (equip & 1)
- bios_drives = (equip >> 6)+1;
- else
- bios_drives = 0;
- }
-
- if (pptr->drivecnt > bios_drives) {
- printf("BIOS equipment byte says count = %d, go with that\n", bios_drives);
- pptr->drivecnt = bios_drives;
+ /* Query drive parameters of this type */
+ memset(&regs, 0, sizeof regs);
+ regs.es = 0;
+ regs.eax.b[1] = 0x08;
+ regs.edx.b[0] = geometry->driveno & 0x80;
+ syscall(0x13, &regs, &regs);
+
+ if ( regs.eflags.l & 1 ) {
+ printf("INT 13 08: Failure, assuming this is the only drive\n");
+ pptr->drivecnt = 0;
+ } else {
+ printf("INT 13 08: Success, count = %u, BPT = %04x:%04x\n",
+ regs.edx.b[0], regs.es, regs.edi.w[0]);
+ pptr->drivecnt = regs.edx.b[0];
+ }
+
+ /* Compare what INT 13h returned with the appropriate equipment byte */
+ if ( geometry->driveno & 0x80 ) {
+ bios_drives = rdz_8(BIOS_HD_COUNT);
+ } else {
+ uint8_t equip = rdz_8(BIOS_EQUIP);
+
+ if (equip & 1)
+ bios_drives = (equip >> 6)+1;
+ else
+ bios_drives = 0;
+ }
+
+ if (pptr->drivecnt > bios_drives) {
+ printf("BIOS equipment byte says count = %d, go with that\n",
+ bios_drives);
+ pptr->drivecnt = bios_drives;
+ }
}
/* Add ourselves to the drive count */