[Galaxy Tab S2 Android Development] T_I:
Yes and no, it's mounted on /mnt/media_rw/<UUID> and accessible only to root. The next step, mounting on /storage/<UUID> failed on my tab with both my image and the T815 image. Looks like there is a difference in hardware next to the lte module.

The error I get from logcat is:

06-14 08:05:20.159 7282 7282 D StorageNotification: Notifying about public volume: VolumeInfo{public:179_33}:
06-14 08:05:20.159 7282 7282 D StorageNotification: type=PUBLIC diskId=disk:179_32 partGuid=null mountFlags=0 mountUserId=0
06-14 08:05:20.159 7282 7282 D StorageNotification: state=CHECKING
06-14 08:05:20.159 7282 7282 D StorageNotification: fsType=null fsUuid=null fsLabel=sdcard
06-14 08:05:20.159 7282 7282 D StorageNotification: path=null internalPath=null
06-14 08:05:20.277 2484 2548 V vold : /dev/block/vold/public:179_33: UUID="90BD-88CD" TYPE="vfat"
06-14 08:05:20.277 3035 3420 D VoldConnector: RCV <- {652 public:179_33 vfat}
06-14 08:05:20.278 3035 3420 D VoldConnector: RCV <- {653 public:179_33 90BD-88CD}
06-14 08:05:20.278 3035 3420 D VoldConnector: RCV <- {654 public:179_33 sdcard}
06-14 08:05:20.278 2484 2548 V vold : /system/bin/fsck_msdos
06-14 08:05:20.278 3035 3420 D VoldConnector: RCV <- {656 public:179_33 /mnt/media_rw/90BD-88CD}
06-14 08:05:20.278 2484 2548 V vold : -p
06-14 08:05:20.278 2484 2548 V vold : -f
06-14 08:05:20.278 2484 2548 V vold : /dev/block/vold/public:179_33
06-14 08:05:20.279 3035 3420 D VoldConnector: RCV <- {655 public:179_33 /mnt/media_rw/90BD-88CD}
06-14 08:05:20.292 2484 2548 I fsck_msdos: ** /dev/block/vold/public:179_33
06-14 08:05:20.294 13571 13571 D fsck_msdos: sectors Per cluster :32
06-14 08:05:20.294 13571 13571 D fsck_msdos: boot->ClusterOffset :29664
06-14 08:05:20.294 13571 13571 I fsck_msdos: FAT32 Filesystem
06-14 08:05:20.294 13571 13571 D fsck_msdos: Using cluster_chain_descriptor
06-14 08:05:20.294 13571 13571 I fsck_msdos: Total clusters 1897505
06-14 08:05:20.295 2484 2548 I fsck_msdos: ** Phase 1 - Read FAT (compare skipped)
06-14 08:05:20.295 2484 2548 I fsck_msdos: Attempting to allocate 7424 KB for FAT
06-14 08:05:20.408 13571 13571 I fsck_msdos: ** Phase 2 - Check Cluster Chains
06-14 08:05:20.408 13571 13571 I fsck_msdos: Begin to handle the cluster chain
06-14 08:05:20.511 13571 13571 D fsck_msdos: rootDir->head :2
06-14 08:05:20.511 2484 2548 I fsck_msdos: ** Phase 3 - Checking Directories
06-14 08:05:20.739 2484 2548 I fsck_msdos: ** Phase 4 - Checking for Lost Files
06-14 08:05:20.739 13571 13571 D fsck_msdos: Verify Filesystem information
06-14 08:05:20.739 13571 13571 W fsck_msdos: 2879 files, 2784672 free (436186 clusters)
06-14 08:05:20.739 13571 13571 I fsck_msdos: free_rb_tree
06-14 08:05:20.742 13571 13571 I fsck_msdos: free_fragment_tree
06-14 08:05:20.742 13571 13571 I fsck_msdos: free_fragment_tree
06-14 08:05:20.742 13571 13571 I fsck_msdos: free_fragment_tree: rb_tree is empty
06-14 08:05:20.751 2484 2548 I Vold : Filesystem check completed OK
06-14 08:05:20.763 3035 3420 D VoldConnector: RCV <- {651 public:179_33 2}
06-14 08:05:20.764 3035 3420 D VoldConnector: RCV <- {200 11 Command succeeded}
06-14 08:05:20.764 3035 3419 E VoldConnector: NDC Command {11 volume mount public:179_33 0 0} took too long (612ms)
06-14 08:05:20.771 7282 7282 D StorageNotification: Notifying about public volume: VolumeInfo{public:179_33}:
06-14 08:05:20.771 7282 7282 D StorageNotification: type=PUBLIC diskId=disk:179_32 partGuid=null mountFlags=0 mountUserId=0
06-14 08:05:20.771 7282 7282 D StorageNotification: state=MOUNTED
06-14 08:05:20.771 7282 7282 D StorageNotification: fsType=vfat fsUuid=90BD-88CD fsLabel=sdcard
06-14 08:05:20.771 7282 7282 D StorageNotification: path=/mnt/media_rw/90BD-88CD internalPath=/mnt/media_rw/90BD-88CD
06-14 08:05:20.771 13194 13194 D ExternalStorage: After updating volumes, found 2 active roots
06-14 08:05:20.779 13194 13194 D ExternalStorage: After updating volumes, found 2 active roots

Just can't figure out why it reports finding 2 active roots (twice even).

Have compiled with latest update in gts2-common, but before and after the flash the tab I have crashes on video. I'm including the stock omx blobs again, just to check if this causes the issues with video. (had them in the cm-12.1 build and no issues with video there)