This allows more flexibility to vvfat backend. The value for "Number of
Heads" and "Sectors per track" are based on SD specifications Part 2.
Some limitations remains, the size parameter is recognized only when
"format=vvfat" is passed. In particular, "format=raw,size=xxx" is
keeping the previously hardcoded value: 504MB for FAT16 and 32 MB for
FAT12. FAT32 has not been adjusted and thus still default to 504MB.
Moreover, for flopyy, size=1M is creating a disk 1.44 MB, and size=2M a
disk of 2.88 MB. This avoids having to worry about float operations.
Signed-off-by: Clément Chigot <chigot@adacore.com>
---
block/vvfat.c | 165 ++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 141 insertions(+), 24 deletions(-)
diff --git a/block/vvfat.c b/block/vvfat.c
index 6526c585a2..4537c39d5c 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1091,6 +1091,11 @@ static QemuOptsList runtime_opts = {
.type = QEMU_OPT_BOOL,
.help = "Do not add a Master Boot Record on this disk",
},
+ {
+ .name = BLOCK_OPT_SIZE,
+ .type = QEMU_OPT_SIZE,
+ .help = "Virtual disk size"
+ },
{ /* end of list */ }
},
};
@@ -1148,10 +1153,141 @@ static void vvfat_parse_filename(const char *filename, QDict *options,
qdict_put_bool(options, "no-mbr", no_mbr);
}
+static void vvfat_get_size_parameters(uint64_t size, BDRVVVFATState *s,
+ bool floppy, Error **errp)
+{
+ if (floppy) {
+ /*
+ * Floppy emulation only supports 1.44 MB or 2.88 MB (default).
+ * In order to avoid floating operations ambiguity, 1 MB is
+ * recognized for 1.44 MB and 2 MB for 2.88 MB.
+ */
+ if (!size) {
+ size = 2 * 1024 * 1024;
+ } else {
+ if (size == 1024 * 1024 && s->fat_type == 16) {
+ error_setg(errp,
+ "floppy FAT16 unsupported size; only support 2M "
+ "(for an effective size of 2.88 MB)");
+ } else if (size != 2 * 1024 * 1024 && size != 1024 * 1024) {
+ error_setg(errp,
+ "floppy unsupported size; should be 1MB (for "
+ "an effective size of 1.44 MB) or 2.88M (for "
+ "2.88MB)");
+ }
+ }
+
+ if (s->fat_type == 12) {
+ if (size == 2 * 1024 * 1024) {
+ s->sectors_per_cluster = 2;
+ } else {
+ s->sectors_per_cluster = 1;
+ }
+ } else {
+ s->sectors_per_cluster = 1;
+ }
+
+ s->sectors_per_track = 36;
+ s->cylinders = 80;
+ s->number_of_heads = 2;
+ } else {
+ /* LATER TODO: if FAT32, adjust */
+ s->sectors_per_cluster = 0x10;
+
+ switch (s->fat_type) {
+ case 12:
+
+ /* Default is 32 MB */
+ if (!size) {
+ size = 32 * 1024 * 1024;
+ } else if (size > 32 * 1024 * 1024) {
+ error_setg(errp, "FAT12 unsupported size; higher than 32Mb");
+ }
+
+ s->cylinders = 64;
+
+ /*
+ * Based on CHS Recommandation table:
+ * Card Capacity | Number of Headers | Sectors per track
+ * ~ 2 MB | 4 | 16
+ * ~ 4 MB | 8 | 16
+ * ~ 8 MB | 16 | 16
+ * ~ 16 MB | 2 | 32
+ * ~ 32 MB | 4 | 32
+ *
+ * For 2 MB, SD is recommending heads = 2 and sectors = 16, but
+ * this requires a different number of cylinders. Thus, it was
+ * adjusted to keep this number constant.
+ */
+ if (size <= 8 * 1024 * 1024) {
+ s->sectors_per_track = 16;
+ } else {
+ s->sectors_per_track = 32;
+ }
+
+ /*
+ * The formula between the size (in bytes) and the parameters are:
+ * size = SECTOR_SIZE * sectors_per_track * number_of_headers *
+ * cylinders
+ */
+ s->number_of_heads = size / s->sectors_per_track /
+ SECTOR_SIZE / s->cylinders;
+ return;
+
+ case 16:
+ /* Default is 504 MB */
+ if (!size) {
+ size = 504 * 1024 * 1024;
+ } else if (size / 1024 > 4 * 1024 * 1024) {
+ error_setg(errp, "FAT16 unsupported size; higher than 4Gb");
+ }
+
+ s->cylinders = 1024;
+
+ /*
+ * Based on CHS Recommandation table:
+ * Card Capacity | Number of Headers | Sectors per track
+ * ~64 MB | 4 | 32
+ * ~128 MB | 8 | 32
+ * ~256 MB | 16 | 32
+ * ~504 MB | 16 | 63
+ * ~1008 MB | 32 | 63
+ * ~2016 MB | 64 | 63
+ */
+ if (size <= 256 * 1024 * 1024) {
+ s->sectors_per_track = 32;
+ } else {
+ s->sectors_per_track = 63;
+ }
+
+ /*
+ * The formula between the size (in bytes) and the parameters are:
+ * size = SECTOR_SIZE * sectors_per_track * number_of_headers *
+ * cylinders
+ */
+ s->number_of_heads = size / s->sectors_per_track /
+ SECTOR_SIZE / s->cylinders;
+ return;
+
+ case 32:
+ /* TODO FAT32 adjust */
+ if (size) {
+ warn_report("size parameters not supported with FAT32;"
+ "default to 504MB.");
+ }
+ s->cylinders = 1024;
+ s->number_of_heads = 16;
+ s->sectors_per_track = 63;
+ return;
+ }
+ }
+}
+
static int vvfat_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
BDRVVVFATState *s = bs->opaque;
+ uint64_t size;
bool floppy;
const char *dirname, *label;
QemuOpts *opts;
@@ -1178,6 +1314,7 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags,
s->fat_type = qemu_opt_get_number(opts, "fat-type", 0);
floppy = qemu_opt_get_bool(opts, "floppy", false);
+ size = qemu_opt_get_size_del(opts, "size", 0);
memset(s->volume_label, ' ', sizeof(s->volume_label));
label = qemu_opt_get(opts, "label");
@@ -1215,35 +1352,15 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags,
goto fail;
}
+ vvfat_get_size_parameters(size, s, floppy, errp);
- if (floppy) {
- /* 2.88MB floppy */
- if (s->fat_type == 12) {
- s->sectors_per_track = 36;
- s->sectors_per_cluster = 2;
- } else {
- s->sectors_per_track = 36;
- s->sectors_per_cluster = 1;
- }
- s->cylinder = 80;
- s->number_of_heads = 2;
- } else {
- /* Reserver space for MBR */
- if (!qemu_opt_get_bool(opts, "no-mbr", false)) {
- s->offset_to_bootsector = 0x3f;
- }
- /* 32MB or 504MB disk*/
- s->cylinders = s->fat_type == 12 ? 64 : 1024;
- s->number_of_heads = 16;
- s->sectors_per_track = 63;
+ /* Reserver space for MBR */
+ if (!floppy && !qemu_opt_get_bool(opts, "no-mbr", false)) {
+ s->offset_to_bootsector = 0x3f;
}
-
s->bs = bs;
- /* LATER TODO: if FAT32, adjust */
- s->sectors_per_cluster=0x10;
-
s->current_cluster=0xffffffff;
s->qcow = NULL;
--
2.34.1
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