Last call for testing the new EDD-first boot code.

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>]

    Last call for testing.  This is going to go in probably ~monday or so.
    It changes the boot code to always try EDD (linear sector number based IO)
    first and only fall back to track/sector/cylinder mode if EDD fails.

					-Matt
					Matthew Dillon 
					<dillon@xxxxxxxxxxxxx>

Index: boot/i386/boot2/boot1.S
===================================================================
RCS file: /cvs/src/sys/boot/i386/boot2/boot1.S,v
retrieving revision 1.8
diff -u -r1.8 boot1.S
--- boot/i386/boot2/boot1.S	27 Jul 2004 19:37:17 -0000	1.8
+++ boot/i386/boot2/boot1.S	17 Sep 2004 20:40:59 -0000
@@ -314,8 +314,43 @@
 //
 // %dl	- byte     - drive number
 // stack - 10 bytes - EDD Packet
-//
-read:	 	push %dx			// Save
+
+read:
+		/*
+		 * Try EDD mode first.  If not enabled or no BIOS support
+		 * exists, fall back to CHS mode.
+		 */
+		testb	$FL_PACKET,%cs:BOOT1_ORIGIN+flags-start
+		jz	read.1
+
+		/*
+		 * BIOS: check extensions present
+		 */
+		mov	$0x55aa,%bx
+		push	%dx
+		movb	$0x41,%ah
+		int	$0x13
+		pop	%dx
+		jc	read.1			/* BIOS error return */
+		cmp	$0xaa55,%bx		/* check for proper magic */
+		jne	read.1
+		testb $0x1,%cl			/* packet interface support? */
+		jz	read.1
+
+		/*
+		 * Issue packet command.
+		 * BIOS: Extended read command
+		 */
+		mov	%bp,%si
+		movb	$0x42,%ah
+		int	$0x13
+		retw
+
+		/*
+		 * Fallback to CHS mode
+		 */
+read.1:
+		push %dx			// Save
 		movb $0x8,%ah			// BIOS: Get drive
 		int $0x13			//  parameters
 		movb %dh,%ch			// Max head number
@@ -338,7 +373,7 @@
 		pop %dx				// Restore
 		cmpl $0x3ff,%eax		// Cylinder number supportable?
 		sti				// Enable interrupts
-		ja read.7			// No, try EDD
+		ja ereturn			// No, failed
 		xchgb %al,%ah			// Set up cylinder
 		rorb $0x2,%al			//  number
 		orb %ch,%al			// Merge
@@ -374,24 +409,8 @@
 read.5: 	shlb %bl			//  buffer
 		add %bl,0x5(%bp)		//  pointer,
 		sub %al,0x2(%bp)		//  block count
-		ja read				// If not done
+		ja read.1			// If not done
 read.6: 	retw				// To caller
-read.7:		testb $FL_PACKET,%cs:BOOT1_ORIGIN+flags-start // LBA support enabled?
-		jz ereturn			// No, so return an error
-		mov $0x55aa,%bx			// Magic
-		push %dx			// Save
-		movb $0x41,%ah			// BIOS: Check
-		int $0x13			//  extensions present
-		pop %dx				// Restore
-		jc return			// If error, return an error
-		cmp $0xaa55,%bx			// Magic?
-		jne ereturn			// No, so return an error
-		testb $0x1,%cl			// Packet interface?
-		jz ereturn			// No, so return an error
-		mov %bp,%si			// Disk packet
-		movb $0x42,%ah			// BIOS: Extended
-		int $0x13			//  read
-		retw				// To caller
 
 // Messages
 
Index: boot/i386/libi386/biosdisk.c
===================================================================
RCS file: /cvs/src/sys/boot/i386/libi386/biosdisk.c,v
retrieving revision 1.6
diff -u -r1.6 biosdisk.c
--- boot/i386/libi386/biosdisk.c	21 Jun 2004 03:38:52 -0000	1.6
+++ boot/i386/libi386/biosdisk.c	17 Sep 2004 20:40:59 -0000
@@ -891,9 +891,14 @@
 	/* correct sector number for 1-based BIOS numbering */
 	sec++;
 
-	/* Loop retrying the operation a couple of times.  The BIOS may also retry. */
+	/*
+	 * Loop retrying the operation a couple of times.  The BIOS may also
+	 * retry.
+	 */
 	for (retry = 0; retry < 3; retry++) {
-	    /* if retrying, reset the drive */
+	    /*
+	     * If retrying, reset the drive.
+	     */
 	    if (retry > 0) {
 		v86.ctl = V86_FLAGS;
 		v86.addr = 0x13;
@@ -902,34 +907,33 @@
 		v86int();
 	    }
 	    
-	    if(cyl > 1023) {
-	        /* use EDD if the disk supports it, otherwise, return error */
-	        if(od->od_flags & BD_MODEEDD1) {
-		    static unsigned short packet[8];
-
-		    packet[0] = 0x10;
-		    packet[1] = x;
-		    packet[2] = VTOPOFF(xp);
-		    packet[3] = VTOPSEG(xp);
-		    packet[4] = dblk & 0xffff;
-		    packet[5] = dblk >> 16;
-		    packet[6] = 0;
-		    packet[7] = 0;
-		    v86.ctl = V86_FLAGS;
-		    v86.addr = 0x13;
-		    v86.eax = 0x4200;
-		    v86.edx = od->od_unit;
-		    v86.ds = VTOPSEG(packet);
-		    v86.esi = VTOPOFF(packet);
-		    v86int();
-		    result = (v86.efl & 0x1);
-		    if(result == 0)
-		      break;
-		} else {
-		    result = 1;
+	    /*
+	     * Always use EDD if the disk supports it, otherwise fall back
+	     * to CHS mode (returning an error if the cylinder number is
+	     * too large).
+	     */
+	    if (od->od_flags & BD_MODEEDD1) {
+		static unsigned short packet[8];
+
+		packet[0] = 0x10;
+		packet[1] = x;
+		packet[2] = VTOPOFF(xp);
+		packet[3] = VTOPSEG(xp);
+		packet[4] = dblk & 0xffff;
+		packet[5] = dblk >> 16;
+		packet[6] = 0;
+		packet[7] = 0;
+		v86.ctl = V86_FLAGS;
+		v86.addr = 0x13;
+		v86.eax = 0x4200;
+		v86.edx = od->od_unit;
+		v86.ds = VTOPSEG(packet);
+		v86.esi = VTOPOFF(packet);
+		v86int();
+		result = (v86.efl & 0x1);
+		if (result == 0)
 		    break;
-		}
-	    } else {
+	    } else if (cyl < 1024) {
 	        /* Use normal CHS addressing */
 	        v86.ctl = V86_FLAGS;
 		v86.addr = 0x13;
@@ -941,7 +945,10 @@
 		v86int();
 		result = (v86.efl & 0x1);
 		if (result == 0)
-		  break;
+		    break;
+	    } else {
+		result = 1;
+		break;
 	    }
 	}
 	
@@ -1034,9 +1041,14 @@
 	dblk += x;
 	resid -= x;
 
-	/* Loop retrying the operation a couple of times.  The BIOS may also retry. */
+	/*
+	 * Loop retrying the operation a couple of times.  The BIOS may also
+	 * retry.
+	 */
 	for (retry = 0; retry < 3; retry++) {
-	    /* if retrying, reset the drive */
+	    /*
+	     * If retrying, reset the drive.
+	     */
 	    if (retry > 0) {
 		v86.ctl = V86_FLAGS;
 		v86.addr = 0x13;
@@ -1044,36 +1056,35 @@
 		v86.edx = od->od_unit;
 		v86int();
 	    }
-	    
-	    if(cyl > 1023) {
-	        /* use EDD if the disk supports it, otherwise, return error */
-	        if(od->od_flags & BD_MODEEDD1) {
-		    static unsigned short packet[8];
-
-		    packet[0] = 0x10;
-		    packet[1] = x;
-		    packet[2] = VTOPOFF(xp);
-		    packet[3] = VTOPSEG(xp);
-		    packet[4] = dblk & 0xffff;
-		    packet[5] = dblk >> 16;
-		    packet[6] = 0;
-		    packet[7] = 0;
-		    v86.ctl = V86_FLAGS;
-		    v86.addr = 0x13;
-			/* Should we Write with verify ?? 0x4302 ? */
-		    v86.eax = 0x4300;
-		    v86.edx = od->od_unit;
-		    v86.ds = VTOPSEG(packet);
-		    v86.esi = VTOPOFF(packet);
-		    v86int();
-		    result = (v86.efl & 0x1);
-		    if(result == 0)
-		      break;
-		} else {
-		    result = 1;
+
+	    /*
+	     * Always use EDD if the disk supports it, otherwise fall back
+	     * to CHS mode (returning an error if the cylinder number is
+	     * too large).
+	     */
+	    if (od->od_flags & BD_MODEEDD1) {
+		static unsigned short packet[8];
+
+		packet[0] = 0x10;
+		packet[1] = x;
+		packet[2] = VTOPOFF(xp);
+		packet[3] = VTOPSEG(xp);
+		packet[4] = dblk & 0xffff;
+		packet[5] = dblk >> 16;
+		packet[6] = 0;
+		packet[7] = 0;
+		v86.ctl = V86_FLAGS;
+		v86.addr = 0x13;
+		    /* Should we Write with verify ?? 0x4302 ? */
+		v86.eax = 0x4300;
+		v86.edx = od->od_unit;
+		v86.ds = VTOPSEG(packet);
+		v86.esi = VTOPOFF(packet);
+		v86int();
+		result = (v86.efl & 0x1);
+		if (result == 0)
 		    break;
-		}
-	    } else {
+	    } else if (cyl < 1024) {
 	        /* Use normal CHS addressing */
 	        v86.ctl = V86_FLAGS;
 		v86.addr = 0x13;
@@ -1085,7 +1096,10 @@
 		v86int();
 		result = (v86.efl & 0x1);
 		if (result == 0)
-		  break;
+		    break;
+	    } else {
+		result = 1;
+		break;
 	    }
 	}