Le 14/09/2020 à 01:46, Michael Schmitz a écrit : > Hi Emmanuel, > > On 9/09/20 7:25 PM, Emmanuel Kasper wrote: >> >>> That almost sounds like libblkid isn't recognizing the FS. Can you try >>> running blkid on the device? If it can't detect the FS type, that might >>> be a place where there is an issue. The libblkid code is not based on >>> the drivers in the kernel, but is still essential for a portion of the >>> auto-detection of file systems in user-space. >> >> Hi Brad >> Indeed blkid does not recognize the FS type, thanks for the hint ! >> >> sudo blkid -p /dev/mmcblk0p1 >> /dev/mmcblk0p1: PART_ENTRY_SCHEME="atari" PART_ENTRY_TYPE="BGM" >> PART_ENTRY_NUMBER="1" PART_ENTRY_OFFSET="2" PART_ENTRY_SIZE="131072" >> PART_ENTRY_DISK="179:256" >> >> I suppose this is because the Atari GEMDOS FAT16 partitions have a >> variable sector size wich is larger that 512 bytes for partitions > >> 16MB, whereas MSDOS FAT16 always uses a 512 bytes sectorsize . > This variable sector size may be what causes the trouble here - see the > commit log of the commit at the head of Geert's m68k-queue. >> >> The disktype tool, provided in the archive, gave me the hint about the >> sector size difference: >> http://disktype.sourceforge.net/doc/ch03s03.html >> and this technical guide, which has all the FAT subtilities explained: >> http://info-coach.fr/atari/documents/_mydoc/Atari_HD_File_Sytem_Reference_Guide.pdf >> >> >> >> sudo disktype /dev/mmcblk0p1 >> --- /dev/mmcblk0p1 >> Block device, size 64 MiB (67108864 bytes) >> FAT16 file system (hints score 3 of 5, ATARI ST bootable) >> Unusual sector size 4096 bytes >> Volume size 63.95 MiB (67051520 bytes, 8185 clusters of 8 KiB) > > According to my recollection, the FAT logical sector size is limited to > 4k by the physical page size (m68k MMU limitation), resulting in a > partition size limit of 256 MB (>128 MB must use 4k logical sectors). > Your partition shows this sector size already below that limit, which is > odd. 8k cluster size with 2 logical sectors of 4k per cluster does > correspond to a TOS partition, though. > > Have you tried to manually mount the partition?
Hi Michael Thanks for the hint about the logical sector size ! I always wondered where this 4k logical sector limit came from on the Linux side. Mounting the partitions with /sbin/mount works well without specifying the FS type, so there is no problem here. However the missing support in libblkid prevents me from using udisks2 / udisksctl to mount the partition as non-root user AFAIK. I wrote to the util-linux mailing as suggested by Adrian as it is the home of libblkid: https://www.spinics.net/lists/util-linux-ng/msg16472.html I have seen they added no sot long ago AHDI partition support, so I have hope they have interest for GEMDOS FAT16 detection too. Emmanuel
