[Qemu-devel] [PATCH 11/11] vvfat: reorganize computation of disk geometry

[Kevin Wolf <kwolf@redhat.com>]

From: Paolo Bonzini <pbonzini@redhat.com>

First determine FAT12/16/32, then compute geometry from that for both
FDD and HDD.  For 1.44MB floppies, and 2.88MB floppies using FAT16,
change to 1 sector/cluster.  The default remains 2.88MB with FAT12
and 2 sectors/cluster.  Both DOS and mkdosfs by default format a 2.88MB
floppy as FAT12.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vvfat.c |   40 ++++++++++++++++++++++++----------------
 1 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/block/vvfat.c b/block/vvfat.c
index faf2947..8511fe5 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -982,7 +982,6 @@ static int is_consistent(BDRVVVFATState *s);
 static int vvfat_open(BlockDriverState *bs, const char* dirname, int flags)
 {
     BDRVVVFATState *s = bs->opaque;
-    int floppy = 0;
     int i;
 
 #ifdef DEBUG
@@ -996,11 +995,8 @@ DLOG(if (stderr == NULL) {
 
     s->bs = bs;
 
-    s->fat_type=16;
     /* LATER TODO: if FAT32, adjust */
     s->sectors_per_cluster=0x10;
-    /* 504MB disk*/
-    bs->cyls=1024; bs->heads=16; bs->secs=63;
 
     s->current_cluster=0xffffffff;
 
@@ -1015,14 +1011,6 @@ DLOG(if (stderr == NULL) {
     if (!strstart(dirname, "fat:", NULL))
 	return -1;
 
-    if (strstr(dirname, ":floppy:")) {
-	floppy = 1;
-	s->fat_type = 12;
-	s->first_sectors_number = 1;
-	s->sectors_per_cluster=2;
-	bs->cyls = 80; bs->heads = 2; bs->secs = 36;
-    }
-
     if (strstr(dirname, ":32:")) {
 	fprintf(stderr, "Big fat greek warning: FAT32 has not been tested. You are welcome to do so!\n");
 	s->fat_type = 32;
@@ -1030,7 +1018,27 @@ DLOG(if (stderr == NULL) {
 	s->fat_type = 16;
     } else if (strstr(dirname, ":12:")) {
 	s->fat_type = 12;
-	bs->secs = 18;
+    }
+
+    if (strstr(dirname, ":floppy:")) {
+	/* 1.44MB or 2.88MB floppy.  2.88MB can be FAT12 (default) or FAT16. */
+	if (!s->fat_type) {
+	    s->fat_type = 12;
+	    bs->secs = 36;
+	    s->sectors_per_cluster=2;
+	} else {
+	    bs->secs=(s->fat_type == 12 ? 18 : 36);
+	    s->sectors_per_cluster=1;
+	}
+	s->first_sectors_number = 1;
+	bs->cyls=80; bs->heads=2;
+    } else {
+	/* 32MB or 504MB disk*/
+	if (!s->fat_type) {
+	    s->fat_type = 16;
+	}
+	bs->cyls=(s->fat_type == 12 ? 64 : 1024);
+	bs->heads=16; bs->secs=63;
     }
 
     s->sector_count=bs->cyls*bs->heads*bs->secs-(s->first_sectors_number-1);
@@ -1058,10 +1066,10 @@ DLOG(if (stderr == NULL) {
 
     if(s->first_sectors_number==0x40)
 	init_mbr(s);
-
-    /* for some reason or other, MS-DOS does not like to know about CHS... */
-    if (floppy)
+    else {
+        /* MS-DOS does not like to know about CHS (?). */
 	bs->heads = bs->cyls = bs->secs = 0;
+    }
 
     //    assert(is_consistent(s));
     qemu_co_mutex_init(&s->lock);
-- 
1.7.6.4