This option tells whether the volume should be partitioned or not. Its default varies: true for hard disks and false for floppy. Its prime effect is to prevent a master boot record (MBR) to be initialized.
This is useful as some operating system (QNX, Rtems) don't recognized FAT mounted disks (especially SD cards) if a MBR is present. Signed-off-by: Clément Chigot <[email protected]> --- block/vvfat.c | 19 ++++++++++++++++--- qapi/block-core.json | 10 +++++++--- 2 files changed, 23 insertions(+), 6 deletions(-) diff --git a/block/vvfat.c b/block/vvfat.c index 814796d918..dd0b3689c1 100644 --- a/block/vvfat.c +++ b/block/vvfat.c @@ -306,7 +306,8 @@ typedef struct BDRVVVFATState { array_t fat,directory,mapping; char volume_label[11]; - uint32_t offset_to_bootsector; /* 0 for floppy, 0x3f for disk */ + /* 0x3f for partitioned disk, 0x0 otherwise */ + uint32_t offset_to_bootsector; unsigned int cluster_size; unsigned int sectors_per_cluster; @@ -1082,6 +1083,11 @@ static QemuOptsList runtime_opts = { .type = QEMU_OPT_BOOL, .help = "Make the image writable", }, + { + .name = "partitioned", + .type = QEMU_OPT_BOOL, + .help = "Do not add a Master Boot Record on this disk", + }, { /* end of list */ } }, }; @@ -1138,7 +1144,7 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags, { BDRVVVFATState *s = bs->opaque; int cyls, heads, secs; - bool floppy; + bool floppy, partitioned; const char *dirname, *label; QemuOpts *opts; int ret; @@ -1165,6 +1171,9 @@ 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); + /* Hard disk are partitioned by default; floppy aren't. */ + partitioned = qemu_opt_get_bool(opts, "partitioned", floppy ? false : true); + memset(s->volume_label, ' ', sizeof(s->volume_label)); label = qemu_opt_get(opts, "label"); if (label) { @@ -1196,7 +1205,6 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags, if (!s->fat_type) { s->fat_type = 16; } - s->offset_to_bootsector = 0x3f; cyls = s->fat_type == 12 ? 64 : 1024; heads = 16; secs = 63; @@ -1215,6 +1223,10 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags, goto fail; } + /* Reserver space for MBR */ + if (partitioned) { + s->offset_to_bootsector = 0x3f; + } s->bs = bs; @@ -3246,6 +3258,7 @@ static const char *const vvfat_strong_runtime_opts[] = { "floppy", "label", "rw", + "partitioned", NULL }; diff --git a/qapi/block-core.json b/qapi/block-core.json index b82af74256..ca438fba51 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -3464,8 +3464,8 @@ # # @fat-type: FAT type: 12, 16 or 32 # -# @floppy: whether to export a floppy image (true) or partitioned hard -# disk (false; default) +# @floppy: whether to export a floppy image (true) or hard disk +# (false; default) # # @label: set the volume label, limited to 11 bytes. FAT16 and FAT32 # traditionally have some restrictions on labels, which are @@ -3474,11 +3474,15 @@ # # @rw: whether to allow write operations (default: false) # +# @partitioned: whether the volume will be partitioned; +# (default: true for hard disk, false for floppy) +# (since 10.2) +# # Since: 2.9 ## { 'struct': 'BlockdevOptionsVVFAT', 'data': { 'dir': 'str', '*fat-type': 'int', '*floppy': 'bool', - '*label': 'str', '*rw': 'bool' } } + '*label': 'str', '*rw': 'bool', '*partitioned': 'bool' } } ## # @BlockdevOptionsGenericFormat: -- 2.43.0
