do bounce-buffering to avoid DMA overrun

somebody, test it!

diff --git a/sys/arch/i386/stand/libsa/biosdev.c b/sys/arch/i386/stand/libsa/biosdev.c
index 3c40b8e..a73ffd9 100644 (file)
--- a/sys/arch/i386/stand/libsa/biosdev.c
+++ b/sys/arch/i386/stand/libsa/biosdev.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: biosdev.c,v 1.5 1997/04/09 08:39:15 mickey Exp $      */
+/*     $OpenBSD: biosdev.c,v 1.6 1997/04/15 06:25:18 mickey Exp $      */
 
 /*
  * Copyright (c) 1996 Michael Shalayeff
@@ -279,7 +279,8 @@ biosstrategy(void *devdata, int rw,
 
        for (i = 0; error == 0 && i < nsect;
             i += n, blk += n, buf += n * DEV_BSIZE) {
-               register int    cyl, hd, sect;
+               register int    cyl, hd, sect, j;
+               void *bb;
 
                btochs(blk, cyl, hd, sect, 
                        BIOSNHEADS(bd->dinfo), BIOSNSECTS(bd->dinfo));
@@ -287,28 +288,50 @@ biosstrategy(void *devdata, int rw,
                        n = BIOSNSECTS(bd->dinfo) - sect;
                else
                        n = nsect - i;
+               
+               /* use a bounce buffer to not to cross 64k DMA boundary */
+               if ((((u_int32_t)buf) & ~0xffff) !=
+                   (((u_int32_t)buf + n * DEV_BSIZE) & ~0xffff)) {
+                       bb = alloc(n * DEV_BSIZE);
+                       if (rw != F_READ)
+                               bcopy (buf, bb, n * DEV_BSIZE);
+               } else
+                       bb = buf;
 #ifdef BIOS_DEBUG
                if (debug)
-                       printf(" (%d,%d,%d,%d)@%p", cyl, hd, sect, n, buf);
+                       printf(" (%d,%d,%d,%d)@%p", cyl, hd, sect, n, bb);
 #endif
-               if (rw == F_READ)
-                       error = biosread (bd->biosdev, cyl, hd, sect, n, buf);
-               else
-                       error = bioswrite(bd->biosdev, cyl, hd, sect, n, buf);
-
-               if (error != 0) {
-                       for (p = bd_errors; p < &bd_errors[bd_nents] &&
-                            p->bd_id != error; p++);
-
-                       if (error == 0x11) /* ECC corrected */
+               for (error = 1, j = 5; error && j--;) {
+                       error = (rw == F_READ)?
+                                 biosread (bd->biosdev, cyl, hd, sect, n, bb)
+                               : bioswrite(bd->biosdev, cyl, hd, sect, n, bb);
+
+                       switch (error) {
+                       case 0x06:      /* disk changed */
+                               printf ("disk changed\n");
+                       default:
+                               continue;
+
+                       case 0x11:      /* ECC corrected */
                                error = 0;
+                               break;
+                       }
+               }
+
+               if (bb != buf) {
+                       if (rw == F_READ)
+                               bcopy (bb, buf, n * DEV_BSIZE);
+                       free (bb, n * DEV_BSIZE);
                }
        }
 
 #ifdef BIOS_DEBUG
        if (debug) {
-               if (error != 0)
+               if (error != 0) {
+                       for (p = bd_errors; p < &bd_errors[bd_nents] &&
+                            p->bd_id != error; p++);
                        printf("=%x(%s)", p->bd_id, p->msg);
+               }
                putchar('\n');
        }
 #endif