[question] cannot read the part of disk when set external SD as ums

[Freed-Wu]

ums_log.tar.gz

when set disk image file as ums, it can work normally.

when i try to set an external sd as ums, the disk can be listed by lsblk in
linux or diskmgmt.msc in windows, but the part of the disk cannot be read.

i have formatted the external sd and try again, but nothing changed. and i make
sure that the mount namespace is global and the software coming from github
is latest.

thanks!

[outofmemo]

Do you mean the part of the disk can't be read in Windows or in Android?

[Freed-Wu]

In android, /mnt/media_rw/B81B-711D

In linux

 >  lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 465.8G  0 disk 
├─sda1   8:1    0   128M  0 part /boot
└─sda2   8:2    0 465.7G  0 part /
sdb      8:16   1  15.4G  0 disk

/dev/sdb is the disk, but the part of it cannot be read.

In windows

> diskmgmt.msc

H: is the disk, but the part of it cannot be read.

[outofmemo]

Maybe there's some thing wrong with the file system.

You can try to plug the USB into a Linux PC to see whether it can be recognized. You can also use tools like parted or DiskGenius to check whether the file system is normal.

[Freed-Wu]

Reproduce Procedure

insert a sdcard to a phone.

ums_interface -> quick start -> start

or

ums_interface -> u disk -> select /dev/block/vold/disk:179:64 -> config usb
gadget

or

ums_interface -> u disk -> select /dev/block/vold/public:179:65 -> config usb
gadget

in linux, lsblk

NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 465.8G  0 disk 
├─sda1   8:1    0   128M  0 part /boot
└─sda2   8:2    0 465.7G  0 part /
sdb      8:16   1  58.2G  0 disk

in windows, diskmgmt.msc, the part also cannot be read.

Effort to Solve

i use a microsd-to-sd or microsd-to-usb to insert the sdcard to computer. in
linux and windows, it also can be read. so the sdcard should be normal.

i buy a new sdcard. now i have 2 sdcard -- 64GB and 16GB, and both of them
can reproduce the issue.

i format the sdcard to fat32 and exfat many times and use different softwares. it still doesn't
change.

Environment

Sdcard

• FS: vfat (fat32) or exfat

Mobile

• Device: Oppo R15x/PBCM10
• OS: color OS v7.1/Android 10

[Freed-Wu]

i try to select /dev/block/mmcblk0 to config usb gadget, and the disk can
display but the part of disk cannot be read. /dev/block/mmcblk0p*
/dev/block/loop* /dev/loop* is same as /dev/block/mmcblk0 and /dev/block/vold/public*

and i try to mount an image file and get failure.

perhaps i should change a mobile to try again?