From 69318c29dba0cd4c58424190e0336a58548b63aa Mon Sep 17 00:00:00 2001
From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Wed, 19 Aug 2015 12:23:26 -0700
Subject: [PATCH] boot - Fix CD booting

* Recent changes to move the loader's heap to high-memory broke the
  CD I/O code due to being beyond the BIOS'es segmentation range.  The
  HDD code was already using bounce buffers, but the CD code was not.

* Adjust the CD I/O code to use bounce buffers too.

Reported-by: numerous.
Testing-by: swildner
---
 sys/boot/pc32/libi386/bioscd.c   | 22 +++++++++++++++++-----
 sys/boot/pc32/libi386/biosdisk.c | 13 ++-----------
 sys/boot/pc32/libi386/libi386.h  | 11 +++++++++++
 3 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/sys/boot/pc32/libi386/bioscd.c b/sys/boot/pc32/libi386/bioscd.c
index 8b992ceb39..afe47ef671 100644
--- a/sys/boot/pc32/libi386/bioscd.c
+++ b/sys/boot/pc32/libi386/bioscd.c
@@ -217,6 +217,7 @@ bc_strategy(void *devdata, int rw, daddr_t dblk, size_t size, char *buf,
 	int unit;
 	int blks;
 #ifdef BD_SUPPORT_FRAGS
+#error "xxx broken code xxx"
 	char fragbuf[BIOSCD_SECSIZE];
 	size_t fragsize;
 
@@ -262,6 +263,7 @@ bc_read(int unit, daddr_t dblk, int blks, caddr_t dest)
 	u_int result, retry;
 	static unsigned short packet[8];
 	int biosdev;
+	int n;
 #ifdef DISK_DEBUG
 	int error;
 #endif
@@ -288,11 +290,15 @@ bc_read(int unit, daddr_t dblk, int blks, caddr_t dest)
 			v86.edx = biosdev;
 			v86int();
 		}
+
+		n = BOUNCEBUF_SIZE / BIOSCD_SECSIZE;
+		if (n > blks)
+			n = blks;
 	    
 		packet[0] = 0x10;
-		packet[1] = blks;
-		packet[2] = VTOPOFF(dest);
-		packet[3] = VTOPSEG(dest);
+		packet[1] = n;
+		packet[2] = VTOPOFF(bounce_base);
+		packet[3] = VTOPSEG(bounce_base);
 		packet[4] = dblk & 0xffff;
 		packet[5] = dblk >> 16;
 		packet[6] = 0;
@@ -305,8 +311,14 @@ bc_read(int unit, daddr_t dblk, int blks, caddr_t dest)
 		v86.esi = VTOPOFF(packet);
 		v86int();
 		result = (v86.efl & PSL_C);
-		if (result == 0)
-			break;
+		if (result == 0) {
+			bcopy(bounce_base, dest, n * BIOSCD_SECSIZE);
+			blks -= n;
+			dest += n * BIOSCD_SECSIZE;
+			if (blks == 0)
+				break;
+			retry = 0;
+		}
 	}
 	
 #ifdef DISK_DEBUG
diff --git a/sys/boot/pc32/libi386/biosdisk.c b/sys/boot/pc32/libi386/biosdisk.c
index 48bd510df0..2cf9407bab 100644
--- a/sys/boot/pc32/libi386/biosdisk.c
+++ b/sys/boot/pc32/libi386/biosdisk.c
@@ -124,12 +124,6 @@ static int	bd_open(struct open_file *f, ...);
 static int	bd_close(struct open_file *f);
 static void	bd_print(int verbose);
 
-/*
- * Max number of sectors to bounce-buffer if the request crosses a 64k boundary
- */
-#define BOUNCEBUF_SIZE	8192
-#define BOUNCEBUF_SECTS	(BOUNCEBUF_SIZE / BIOSDISK_SECSIZE)
-
 struct devsw biosdisk = {
     "disk", 
     DEVT_DISK, 
@@ -148,11 +142,8 @@ static int	bd_bestslice(struct open_disk *od);
 static void	bd_chainextended(struct open_disk *od, u_int32_t base,
 					u_int32_t offset);
 
-/*
- * Bounce buffers can no longer be malloc()'d because the malloc pool
- * now uses high memory.  Declare statically.
- */
-static char	bounce_base[BOUNCEBUF_SIZE];
+char	bounce_base[BOUNCEBUF_SIZE];	/* also used by CD code */
+
 
 /*
  * Translate between BIOS device numbers and our private unit numbers.
diff --git a/sys/boot/pc32/libi386/libi386.h b/sys/boot/pc32/libi386/libi386.h
index 228cd50ef2..78f77edead 100644
--- a/sys/boot/pc32/libi386/libi386.h
+++ b/sys/boot/pc32/libi386/libi386.h
@@ -72,6 +72,17 @@ write_eflags(u_int ef)
 	__asm __volatile("pushl %0; popfl" : : "r" (ef));
 }
 
+/*
+ * Max number of sectors to bounce-buffer if the request crosses a 64k boundary
+ *
+ * Bounce buffers can no longer be malloc()'d because the malloc pool
+ * now uses high memory.  Declare statically.
+ */
+#define BOUNCEBUF_SIZE  8192
+#define BOUNCEBUF_SECTS (BOUNCEBUF_SIZE / BIOSDISK_SECSIZE)
+
+extern char	bounce_base[BOUNCEBUF_SIZE];
+
 int	i386_getdev(void **vdev, const char *devspec, const char **path);
 char	*i386_fmtdev(void *vdev);
 int	i386_setcurrdev(struct env_var *ev, int flags, const void *value);
-- 
2.41.0