can a SD card be used as storage with emmc boot

[pfeerick]

hello
booting from emmc
so SD slot not used
but
can i use it for storage?
used lsblk, with a SD card inserted [format: ntfs-3], showed up as /dev/mmcblk1 [emmc was /dev/mmcblk0]
but mount failed, [tried a few different options]
also edited fstab, /dev/mmcblk /mnt/SD/ ntfs-3 auto rw 0 0
but the rock tried to boot from SD, which was empty, [had to remove above line from fstab]
can you please advise want to do
thanks

actually used an usb stick which automounted fine [mounted as /dev/sda]

As others have indicated, yes you can (use the SD card as storage if booting from the eMMC).

First you'll want to check out what is on the SD card (sudo fdisk -l /dev/mmcblk1). Find out what partitions are on it, and what file system type. Is it really NTFS, or is it fat(16/32)? This is the output when the SD card is another boot image, although I'm not using it at the moment as the rock64 is booting from the eMMC.

Code:

Disk /dev/mmcblk1: 7.4 GiB, 7948206080 bytes, 15523840 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 305CD6FF-4953-4D14-AD69-3A11874A2E0B

Device          Start      End  Sectors  Size Type
/dev/mmcblk1p1     64     8063     8000  3.9M Linux filesystem
/dev/mmcblk1p2   8064     8191      128   64K Linux filesystem
/dev/mmcblk1p3   8192    16383     8192    4M Linux filesystem
/dev/mmcblk1p4  16384    24575     8192    4M Linux filesystem
/dev/mmcblk1p5  24576    32767     8192    4M Linux filesystem
/dev/mmcblk1p6  32768   262143   229376  112M Microsoft basic data
/dev/mmcblk1p7 262144 15523806 15261663  7.3G Linux filesystem

Here, there are a bunch of linux (probably ext4) partiions, with the most interesting being the last two (p6 & p7). I should be about the mount either of them with no trouble, after making suitable directories upon which to mount them.

So for somewhere to mount them:

Code:

sudo mkdir /mnt/sd-boot; sudo mkdir /mnt/sd-os

And to actually mount them:

Code:

sudo mount /dev/mmcblk1p6 /mnt/sd-boot; sudo mount /dev/mmcblk1p7 /mnt/sd-os

Interestingly enough I didn't need to specify the -t flag to let mount know the type. Not sure why it was so co-operative... I was expecting to need to specify vfat and ext4, but it mount worked it out on it's own this time.