search for: sectors_per_fat

...y being created will occupy one Cluster: 64 Sectors in our example. _ The first Cluster of the Data Area corresponds to FAT_entry #2 (as FAT_entries #0 and #1 are reserved). The above values are the ones we are taking as "known". Now, for simplicity, I am going to take the value of Sectors_per_FAT that Ridgecrop's Large FAT32 formatting tool used for our example: Sectors per FAT: 23843 With this Sectors_per_FAT value, the corresponding Maximum FAT entries: 23843 * 128 = 3'051'904 Since the first 2 FAT entries are reserved, then the corresponding Maximum Amount of Clusters...

Hi Ady, On 2016.02.25 02:08, Ady via Syslinux wrote: > There is an "extra" sector, in comparison to... what exactly? Sorry if I wasn't clear. I think I implied that the Large FAT32 fat size had an extra sector compared to minfatsize, when of course I meant the opposite (the Large FAT32 has one less sector than the minfatsize computed by the unpatched code, hence the check

...ntence would be "too strong". Second, the sentence should clarify that it refers to FAT32 only, since FAT12/16 would be different. This difference is part of the problem, particularly around the edges of: _ accepted valid values for total amount of Clusters; _ accepted valid values for Sectors_per_FAT; _ accepted valid values for the type of FAT (12/16/32); and, _ the relation between all of the above. So, for FAT32, the potential maximum amount of Sectors for Data would be: Fo = To - ( Nf * Fs ) - Rs (This formula is the same as Pete wrote it; I commented only about the sentence explaini...

...Bytes per Sector: 512 > _ FAT Entries per Sector: 128 > _ Reserved Sectors: 32 > _ Volume's Total Sectors: 195'369'519 > _ Sectors per Cluster: 64 > _ Amount of FATs: 2 > _ Root Directory Sectors: 0 (please keep reading) > Sectors per FAT: 23843 > > With this Sectors_per_FAT value, the corresponding > > Maximum FAT entries: > 23843 * 128 = 3'051'904 > > Since the first 2 FAT entries are reserved, then the corresponding > > Maximum Amount of Clusters: > 3'051'904 - 2 = 3'051'902 > > The amount of Sectors in the D...

...lues that are around or close to the limits between FAT12/16/32. For simplicity, I'll give basic examples (which I have not truly analyzed; developers could / should test relevant code). Example A: Volume_Total_Sectors: 66'463 FAT type: FAT32 Bytes_per_sector: 512 Sectors_per_Cluster: 1 Sectors_per_FAT: 511 ---> this value should _not_ be accepted as valid minfatsize; 512 should be OK. Example B: Volume_Total_Sectors: 4'187'104 FAT type: FAT32 Bytes_per_sector: 512 Sectors_per_Cluster: 64 Sectors_per_FAT: 511 ---> this value should _not_ be accepted as valid minfatsize; 512 shoul...

Hi Ady, I won't comment on the reasons why the original computation was wrong, but thanks for the detailed analysis. On 2016.02.26 08:05, Ady via Syslinux wrote: >> Thus we can finally get a formula for Fs that satisfies the above: >> >> Fs = (To - Rs + Nf * Cs) / ((Ss * Cs / Fe) + Nf) + 1 > > I believe such formula is slightly inaccurate too. > > My

...SECTORS_PER_CLUSTER; + floppy->bootsect.reserved_sectors = htole16 (32); + floppy->bootsect.nr_fats = 2; + floppy->bootsect.nr_root_dir_entries = htole16 (0); + floppy->bootsect.old_nr_sectors = htole16 (0); + floppy->bootsect.media_descriptor = 0xf8; + floppy->bootsect.old_sectors_per_fat = htole16 (0); + floppy->bootsect.sectors_per_track = htole16 (0); + floppy->bootsect.nr_heads = htole16 (0); + floppy->bootsect.nr_hidden_sectors = htole32 (0); + floppy->bootsect.nr_sectors = htole32 (floppy->data_last_sector + 1); + + floppy->bootsect.sectors_per_fat = +...

Add nbdkit-floppy-plugin, “inspired” by qemu's VVFAT driver, but without the ability to handle writes. The implementation is pretty complete, supporting FAT32, LFNs, volume labels, timestamps, etc, and it passes both ‘make check’ and ‘make check-valgrind’. Usage is simple; to serve the current directory: $ nbdkit floppy . Then using guestfish (or any NBD client): $ guestfish --ro