I booted to Rasbian, unmounted all of the other partitions that had been automatically mounted, and shrank a large partition to clear some space. I created a new FAT32 partition and now I have a shared data space that I can also see and use in Windows if I need to.
Interestingly, the new partition number is (obviously) after all of the existing partition numbers, but created in the space between two OSs. So, sfdisk -l tells me that "Partition table entries are not in disk order. (The last one in this list)
Code: Select all
sudo sfdisk -l
...
Device Boot Start End Sectors Size Id Type
/dev/mmcblk0p1 8192 137215 129024 63M e W95 FAT16 (LBA)
/dev/mmcblk0p2 137216 124735487 124598272 59.4G 5 Extended
/dev/mmcblk0p5 139264 204797 65534 32M 83 Linux
/dev/mmcblk0p6 204800 729085 524286 256M c W95 FAT32 (LBA)
/dev/mmcblk0p7 729088 29253629 28524542 13.6G 83 Linux
/dev/mmcblk0p8 29253632 29691903 438272 214M c W95 FAT32 (LBA)
/dev/mmcblk0p9 29696000 54878205 25182206 12G 83 Linux
/dev/mmcblk0p10 54878208 55400447 522240 255M c W95 FAT32 (LBA)
/dev/mmcblk0p11 55402496 88791039 33388544 15.9G 83 Linux
/dev/mmcblk0p12 101015552 101533695 518144 253M c W95 FAT32 (LBA)
/dev/mmcblk0p13 101539840 124735487 23195648 11.1G 83 Linux
/dev/mmcblk0p14 88793088 101013503 12220416 5.8G b W95 FAT32
Partition table entries are not in disk order.

Unrelated question:
Am I right that there is nothing in the PINN UI to continue to the boot menu after I have pressed the shift key during boot? I have to press the ESC key in the PINN UI to show the installed OS boot menu?