create iso images with a non floppy emulation bootblock.
all this patch does is to add the -B option, wich is like
-b but sets the type of the bootblock to non emulation
so that bootblock has full lba access to the iso filesystem.

Reference: /n/sources/patch/applied/dump9660-noemu-bootblock
Date: Sun Mar 28 23:30:54 CES 2010
Signed-off-by: cinap_lenrek@gmx.de

--- /sys/src/cmd/disk/9660/boot.c	Sun Mar 28 23:27:37 2010
+++ /sys/src/cmd/disk/9660/boot.c	Sun Mar 28 23:27:34 2010
@@ -149,6 +149,7 @@
 Cupdatebootcat(Cdimg *cd)
 {
 	uvlong o;
+	int n;
 
 	if(cd->bootdirec == nil)
 		return;
@@ -156,20 +157,33 @@
 	o = Cwoffset(cd);
 	Cwseek(cd, cd->bootimageptr);
 	Cputc(cd, 0x88);
-	switch(cd->bootdirec->length){
-	default:
-		fprint(2, "warning: boot image is not 1.44MB or 2.88MB; pretending 1.44MB\n");
-	case 1440*1024:
-		Cputc(cd, 0x02);	/* 1.44MB disk */
-		break;
-	case 2880*1024:
-		Cputc(cd, 0x03);	/* 2.88MB disk */
-		break;
+
+	if(cd->flags & CDbootnoemu){
+		Cputc(cd, 0x00);	/* no disk emulation */
+	} else {
+		switch(cd->bootdirec->length){
+		default:
+			fprint(2, "warning: boot image is not 1.44MB or 2.88MB; pretending 1.44MB\n");
+		case 1440*1024:
+			Cputc(cd, 0x02);	/* 1.44MB disk */
+			break;
+		case 2880*1024:
+			Cputc(cd, 0x03);	/* 2.88MB disk */
+			break;
+		}
 	}
 	Cputnl(cd, 0, 2);	/* load segment */
 	Cputc(cd, 0);	/* system type */
 	Cputc(cd, 0);	/* unused */
-	Cputnl(cd, 1, 2);	/* 512-byte sector count for load */
+	n = 1;	
+	if(cd->flags & CDbootnoemu){
+		n = (cd->bootdirec->length+511)/512;
+		if(n > 4){
+			fprint(2, "warning: boot image too big; will only load the first 2K\n");
+			n = 4;
+		}
+	}
+	Cputnl(cd, n, 2);	/* 512-byte sector count for load */
 	Cputnl(cd, cd->bootdirec->block, 4);	/* ptr to disk image */
 	Cwseek(cd, o);	
 }
--- /sys/src/cmd/disk/9660/cdrdwr.c	Sun Mar 28 23:27:42 2010
+++ /sys/src/cmd/disk/9660/cdrdwr.c	Thu Jul 15 00:44:22 2010
@@ -44,7 +44,7 @@
 	Cputisopvd(cd, info);
 	if(info.flags & CDbootable){
 		cd->bootimage = info.bootimage;
-		cd->flags |= CDbootable;
+		cd->flags |= info.flags & (CDbootable|CDbootnoemu);
 		Cputbootvol(cd);
 	}
 
--- /sys/src/cmd/disk/9660/dump9660.c	Sun Mar 28 23:27:47 2010
+++ /sys/src/cmd/disk/9660/dump9660.c	Sun Mar 28 23:27:44 2010
@@ -77,6 +77,9 @@
 	case 'a':
 		doabort = 1;
 		break;
+	case 'B':
+		info.flags |= CDbootnoemu;
+		/* no break */
 	case 'b':
 		if(!mk9660)
 			usage();
--- /sys/src/cmd/disk/9660/iso9660.h	Sun Mar 28 23:27:53 2010
+++ /sys/src/cmd/disk/9660/iso9660.h	Sun Mar 28 23:27:50 2010
@@ -133,6 +133,7 @@
 	CDnew = 1<<4,
 	CDdump = 1<<5,
 	CDbootable = 1<<6,
+	CDbootnoemu = 1<<7,
 };
 
 typedef struct Tx Tx;