From 02b692d367343df7eed8c1b1a0f435424e8b3a56 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Tue, 14 Oct 2008 14:38:04 -0700
Subject: [PATCH] MEMDISK: default to "safeint" mode

There is enough evidence that "safeint" is a decent compromise between
The Right Thing[TM] and dealing with the reality of ultra-broken
DOSen.  Make it the default.

Clean up some of the command-line parsing code and status printing.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 NEWS            |  1 +
 doc/memdisk.txt |  4 ++++
 memdisk/setup.c | 58 +++++++++++++++++++++++++++++++++++++++------------------
 3 files changed, 45 insertions(+), 18 deletions(-)

diff --git a/NEWS b/NEWS
index adb77c8..76ad4be 100644
--- a/NEWS
+++ b/NEWS
@@ -8,6 +8,7 @@ Changes in 3.73:
 	* Handle systems with E820 "extended attributes" per ACPI 3.
 	  Someone "cleverly" decided to change the E820 spec in a
 	  backwards-incompatible manner!
+	* MEMDISK: default to "safeint".
 
 Changes in 3.72:
 	* Include the pxechain.com module from Jeffery Hutzelman at
diff --git a/doc/memdisk.txt b/doc/memdisk.txt
index 531706e..6c994f9 100644
--- a/doc/memdisk.txt
+++ b/doc/memdisk.txt
@@ -105,8 +105,12 @@ d) MEMDISK normally uses the BIOS "INT 15h mover" API to access high
    bigraw	Use raw access to protected mode memory, and leave the
 		CPU in "big real" mode afterwards.
 
+   int		Use plain INT 15h access to protected memory.  This assumes
+   		that anything which hooks INT 15h knows what it is doing.
+
    safeint	Use INT 15h access to protected memory, but invoke
 		INT 15h the way it was *before* MEMDISK was loaded.
+		This is the default since version 3.73.
 
 e) MEMDISK by default supports EDD/EBIOS on hard disks, but not on
    floppy disks.  This can be controlled with the options:
diff --git a/memdisk/setup.c b/memdisk/setup.c
index 5fc2aa0..8e8ded1 100644
--- a/memdisk/setup.c
+++ b/memdisk/setup.c
@@ -115,6 +115,7 @@ struct patch_area {
 #define CONFIG_RAW	0x02
 #define CONFIG_SAFEINT	0x04
 #define CONFIG_BIGRAW	0x08		/* MUST be 8! */
+#define CONFIG_MODEMASK	0x0e
 
   uint16_t mystack;
   uint16_t statusptr;
@@ -648,14 +649,6 @@ __cdecl void setup(__cdecl syscall_t cs_syscall, void *cs_bounce)
   else
     do_edd = (geometry->driveno & 0x80) ? 1 : 0;
 
-  printf("Disk is %s %d, %u%s K, C/H/S = %u/%u/%u, EDD %s\n",
-	 (geometry->driveno & 0x80) ? "hard disk" : "floppy",
-	 geometry->driveno & 0x7f,
-	 geometry->sectors >> 1,
-	 (geometry->sectors & 1) ? ".5" : "",
-	 geometry->c, geometry->h, geometry->s,
-	 do_edd ? "on" : "off");
-
   /* Reserve the ramdisk memory */
   insertrange(ramdisk_image, ramdisk_size, 2, 1);
   parse_mem();			/* Recompute variables */
@@ -682,27 +675,56 @@ __cdecl void setup(__cdecl syscall_t cs_syscall, void *cs_bounce)
 
   pptr->bootloaderid = shdr->type_of_loader;
 
-  pptr->configflags = 0;
+  pptr->configflags = CONFIG_SAFEINT; /* Default */
   /* Set config flags */
   if ( getcmditem("ro") != CMD_NOTFOUND ) {
-    puts("Marking disk readonly\n");
     pptr->configflags |= CONFIG_READONLY;
   }
   if ( getcmditem("raw") != CMD_NOTFOUND ) {
-    puts("Using raw access to high memory\n");
-    pptr->configflags &= ~CONFIG_SAFEINT|CONFIG_BIGRAW;
+    pptr->configflags &= ~CONFIG_MODEMASK;
     pptr->configflags |= CONFIG_RAW;
   }
+  if ( getcmditem("bigraw") != CMD_NOTFOUND ) {
+    pptr->configflags &= ~CONFIG_MODEMASK;
+    pptr->configflags |= CONFIG_BIGRAW|CONFIG_RAW;
+  }
+  if ( getcmditem("int") != CMD_NOTFOUND ) {
+    pptr->configflags &= ~CONFIG_MODEMASK;
+    /* pptr->configflags |= 0; */
+  }
   if ( getcmditem("safeint") != CMD_NOTFOUND ) {
-    puts("Using safe INT 15h access to high memory\n");
-    pptr->configflags &= ~CONFIG_RAW|CONFIG_BIGRAW;
+    pptr->configflags &= ~CONFIG_MODEMASK;
     pptr->configflags |= CONFIG_SAFEINT;
   }
-  if ( getcmditem("bigraw") != CMD_NOTFOUND ) {
-    puts("Using raw access to high memory - assuming big real mode\n");
-    pptr->configflags &= ~CONFIG_SAFEINT;
-    pptr->configflags |= CONFIG_BIGRAW|CONFIG_RAW;
+
+  printf("Disk is %s %d, %u%s K, C/H/S = %u/%u/%u, EDD %s, %s\n",
+	 (geometry->driveno & 0x80) ? "hard disk" : "floppy",
+	 geometry->driveno & 0x7f,
+	 geometry->sectors >> 1,
+	 (geometry->sectors & 1) ? ".5" : "",
+	 geometry->c, geometry->h, geometry->s,
+	 do_edd ? "on" : "off",
+	 pptr->configflags & CONFIG_READONLY ? "readonly" : "read-write");
+
+  puts("\nUsing ");
+  switch (pptr->configflags & CONFIG_MODEMASK) {
+  case 0:
+    puts("standard INT 15h");
+    break;
+  case CONFIG_SAFEINT:
+    puts("safe INT 15h");
+    break;
+  case CONFIG_RAW:
+    puts("raw");
+    break;
+  case CONFIG_RAW|CONFIG_BIGRAW:
+    puts("big real mode raw");
+    break;
+  default:
+    printf("unknown %#x", pptr->configflags & CONFIG_MODEMASK);
+    break;
   }
+  puts(" access to high memory\n");
 
   /* pptr->maxint13func defaults to EDD enabled, if compiled in */
   if (!do_edd)
-- 
2.7.4