MBR supports 4K sectors

Fixed code that prevented 4K sectors in MBR partitions up to 16 TB

FATtools/Volume.py

@@ -51,7 +51,7 @@ def vopen(path, mode='rb', what='auto'):
     if what == 'disk':
         return d
     # Tries to access a partition
-    mbr = MBR(d.read(PHYS_SECTOR), disksize=d.size)
+    mbr = MBR(d.read(PHYS_SECTOR), disksize=d.size, sector=PHYS_SECTOR)
     if DEBUG&2: log("Opened MBR: %s", mbr)
     valid_mbr=1
     n = mbr.partitions[0].size()
@@ -114,7 +114,7 @@ def vopen(path, mode='rb', what='auto'):
             extpart = part
             while wanted <=partition:
                 bs = extpart.read(PHYS_SECTOR)
-                ebr = MBR(bs, disksize=d.size) # reads Extended Boot Record
+                ebr = MBR(bs, disksize=d.size, sector=PHYS_SECTOR) # reads Extended Boot Record
                 if DEBUG&2: log("Opened EBR: %s", ebr)
                 if ebr.wBootSignature != 0xAA55:
                     if DEBUG&2: log("Invalid Extended Boot Record")

FATtools/mkfat.py

@@ -41,7 +41,8 @@
 
 cluster size wanted by user, from 2^9 to 2^16 bytes. If sector size is 4096
 bytes, size is up to 2^18 (256K). If not specified, the best value is
-selected automatically.
+selected automatically. Windows 11 seems able to read/write a FAT32 volume
+formatted with a 512K cluster, the maximum size a boot sector can record.
 
 fat_no_64K_cluster
 
@@ -130,7 +131,7 @@ def fat_mkfs(stream, size, sector=512, params={}):
     # Calculate possible combinations for each FAT and cluster size
     for fat_slot_size in fat_slot_sizes:
         allowed = {} # {cluster_size : fsinfo}
-        for i in range(9, max_cluster): # cluster sizes 0.5K...32K (64K)
+        for i in range(9, max_cluster): # cluster sizes 0.5K...32K (64K) or 128K-256K with 4Kn sectors
             fsinfo = {}
             root_entries = params.get('root_entries', {12:224,16:512,32:0}[fat_slot_size])
             root_entries_size = (root_entries*32)+(sector-1)//sector # translate into sectors

FATtools/partutils.py

@@ -162,7 +162,7 @@ def __init__ (self, s=None, offset=0, stream=None, disksize=0, sector=512):
         for k, v in list(self._kv.items()):
             self._vk[v[0]] = k
         for i in range(4):
-            self.partitions += [MBR_Partition(self._buf, index=i)]
+            self.partitions += [MBR_Partition(self._buf, index=i, sector=sector)]
             # try to detect disk geometry
             ret = self.partitions[-1].geometry()
             if ret == -1: continue
@@ -232,7 +232,7 @@ def mkpart(self, offset, size):
             c = size // self._sector // (h*s)
             if DEBUG&1: log("mkpart: CHS geometry %d-%d-%d (disk based)",c,h,s)
         if c > 1024 or not self.heads_per_cyl:
-            c, h, s = get_geometry(size)
+            c, h, s = get_geometry(size, self._sector)
             self.heads_per_cyl = h
             self.sectors_per_cyl = s
             if DEBUG&1: log("mkpart: CHS geometry %d-%d-%d (calculated)",c,h,s)
@@ -275,7 +275,7 @@ def partition(disk, fmt='gpt', options={}):
         if options.get('lba_mode',0):
             mbr.setpart(0, 1<<20, part_size-(1<<20)-33*SECTOR)
         else:
-            mbr.setpart(0, mbr.sectors_per_cyl*512, part_size-mbr.sectors_per_cyl*SECTOR)
+            mbr.setpart(0, mbr.sectors_per_cyl*SECTOR, part_size-mbr.sectors_per_cyl*SECTOR)
         if options.get('mbr_type'):
             mbr.partitions[0].bType = options.get('mbr_type')
         else:

FATtools/scripts/mkfat.py

@@ -12,10 +12,10 @@ def create_parser(parser_create_fn=argparse.ArgumentParser,parser_create_args=No
     par.add_argument('fs',help="The image file or disk device to write to",metavar="FS")
     par.add_argument("-t", "--fstype", dest="fs_type", help="try to apply the specified File System between FAT12, FAT16, FAT32 or EXFAT. Default: based on medium size.", metavar="FSTYPE")
     par.add_argument("-c", "--cluster", dest="cluster_size", help="force a specified cluster size between 512, 1024, 2048, 4096, 8192, 16384, 32768 (since DOS) or 65536 bytes (Windows NT+; 128K and 256K clusters are allowed with 4K sectors) for FAT. exFAT permits clusters up to 32M. Default: based on medium size. Accepts 'k' and 'm' postfix for Kibibytes and Mebibytes.", metavar="CLUSTER")
-    par.add_argument("-p", "--partition", dest="part_type", help="create a single partition from all disk space before formatting. Accepts MBR, GPT or MBR_OLD (2 GB max, MS-DOS <7.1 compatible)", metavar="PARTTYPE")
+    par.add_argument("-p", "--partition", dest="part_type", help="create a single partition from all disk space before formatting. Accepts MBR (up to 2 TB; 16 TB with 4K sectors), GPT or MBR_OLD (2 GB max, MS-DOS <7.1 compatible)", metavar="PARTTYPE")
     par.add_argument("--fat32compat", action="store_true",  dest="fat32_compat", help="FAT32 is applied in Windows XP compatibility mode, i.e. only if 65525 < clusters < 4177918 (otherwise: 2^28-11 clusters allowed)")
     par.add_argument("--no-fat12", action="store_true",  dest="fat12_disable", help="FAT12 is never applied to small hard disks (~127/254M on DOS/NT systems)")
-    par.add_argument("--no-64k-cluster", action="store_true",  dest="disable_64k", help="do not use 64K clusters (DOS compatibility)")
+    par.add_argument("--no-64k-cluster", action="store_true",  dest="disable_64k", help="cluster size is limited to 32K (DOS compatibility)")
     return par
 
 def call(args):
@@ -26,6 +26,7 @@ def call(args):
 
     SECTOR = 512
     if dsk.type() == 'VHDX' and dsk.metadata.physical_sector_size == 4096: SECTOR = 4096
+    opts={'phys_sector':SECTOR}
 
     # Windows 10 Shell (or START command) happily auto-mounts a VHD ONLY IF partitioned and formatted
     # However, a valid VHD is always mounted and can be handled with Diskpart (GUI/CUI)
@@ -37,24 +38,23 @@ def call(args):
         print("Creating a %s partition with all disk space..."%t.upper())
         if t in ('mbr', 'mbr_old'):
             if dsk.size > (2<<40): 
-                print('You MUST use GPT partition scheme with disks >2TB!')
+                if SECTOR==512: 
+                    print('You MUST use GPT partition scheme with disks >2TB!')
+                    sys.exit(1)
+            opts['lba_mode'] = 1
+            if dsk.size > (16<<40) and SECTOR==4096: 
+                print('You MUST use GPT partition scheme with 4K sectored disks >16TB!')
                 sys.exit(1)
-            #~ if dsk.size > (2<<40) and SECTOR==512: 
-                #~ print('You MUST use GPT partition scheme with disks >2TB!')
-                #~ sys.exit(1)
-            #~ if dsk.size > (16<<40) and SECTOR==4096: 
-                #~ print('You MUST use GPT partition scheme with 4K sectored disks >16TB!')
-                #~ sys.exit(1)
             if t == 'mbr_old':
                 if dsk.size > (2<<30): print('Warning: old DOS does not like primary partitions >2GB, size reduced automatically!')
                 partutils.partition(dsk, 'mbr', {'compatibility':0})
                 if args.fs_type and args.fs_type.lower() == 'fat32':
                     args.fs_type = 'fat16'
                     print('Warning: old DOS does not know FAT32, switching to FAT16.')
             else:
-                partutils.partition(dsk, 'mbr', options={'phys_sector':SECTOR})
+                partutils.partition(dsk, 'mbr', options=opts)
         else:
-            partutils.partition(dsk, 'gpt', options={'phys_sector':SECTOR})
+            partutils.partition(dsk, 'gpt', options=opts)
         dsk.close()
         dsk = vopen(args.fs, 'r+b', 'partition0')
         if type(dsk) == type(''):
@@ -63,7 +63,6 @@ def call(args):
         else:
             print("Disk was correctly partitioned with %s scheme."%t.upper())
 
-
     params = {}
 
     if args.fs_type:
@@ -119,7 +118,7 @@ def call(args):
         else:
             if params['fat_bits'] == 32:
                 dsk.mbr.partitions[0].bType = 0xB
-                if dsk.size > 1024*255*63*512: dsk.mbr.partitions[0].bType = 0xC
+                if dsk.size > 1024*255*63*SECTOR: dsk.mbr.partitions[0].bType = 0xC
             elif params['fat_bits'] == 16:
                 dsk.mbr.partitions[0].bType = 6
                 if dsk.size < (32<<20): dsk.mbr.partitions[0].bType = 4

FATtools/utils.py

@@ -119,7 +119,7 @@ def get_geometry(size, sector=512):
         s = 63
         h = 255
         c = sectors // (h*s)
-    if DEBUG&1: log("%d cylinders with %d heads and %d sectors (CxHxSx512=%d bytes)",c,h,s,c*h*s*sector)
+    if DEBUG&1: log("%d cylinders with %d heads and %d sectors (CxHxSx%d=%d bytes)",c,h,s,sector,c*h*s*sector)
     return c, h, s
 
 def chs2lba(c, h, s, hpc, spc):

FATtools/version.py

@@ -1 +1 @@
-__version__ = '1.0.20'
+__version__ = '1.0.21'