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My goal is to convincingly emulate a well known brand of USB Flash Disk, using Raspberry Pi Zero (with or without Wifi). For the sake of this example, I want to emulate a 4GB Sandisk Cruzer Edge, but generally speaking I want the ability to have full control of idVendor, idProduct, iProduct, iManufacturer, iSerial (and any other subtle variables of a USB flash disk)

I only want USB Mass Storage, not a composite device (with HID, or ethernet or serial or anything else)

My target USB Host devices range from: Linux AMD64, Linux MIPS, Linux ARM, Windows x86 I've activated dwc2, partitioned and formatted the file that is to be used as the storage & filesystem and loaded g_mass_storage. It is working fine from the perspective that it successfully mounts the Storage on all targets - I can connect and see the contents, add/delete files, eject and reconnect, seeing changes fine.

I use this to launch the USB Mass Storage gadget:

sudo modprobe g_mass_storage file=/home/pi/piusb_fat32.bin nofua=1 luns=1 ro=0 stall=0 removable=1 cdrom=0 idVendor=0x0781 idProduct=0x556e bcdDevice=0x0103 iManufacturer="SanDisk" iProduct="Cruzer Edge" iSerialNumber="990431108215FFF05368"

The problem is that the name of the device remains as Linux File-Stor Gadget. Under Linux & Windows respectively:

  • Linux File-Stor Gadget 0414
  • USBSTOR\DISK&VEN_LINUX&PROD_FILE-STOR_GADGET&REV_0414

When the pi is connected to Windows 10 1903 x86 laptop, I see two devices appear:

Get-WmiObject Win32_USBControllerDevice -ComputerName localhost -Impersonation Impersonate -Authentication PacketPrivacy | Foreach-Object { [Wmi]$_.Dependent } | Sort-Object PNPClass | ft Name, PNPClass, PNPDeviceID Name PNPClass PNPDeviceID ---- -------- ----------- Linux File-Stor Gadget USB Device DiskDrive USBSTOR\DISK&VEN_LINUX&PROD_FILE-STOR_GADGET&REV_0414\990431108215FFF05368&0 USB Mass Storage Device USB USB\VID_0781&PID_556E\990431108215FFF05368

Whereas with the real Sandisk USB Flash Disk:

Name PNPClass PNPDeviceID ---- -------- ----------- SanDisk Cruzer Edge USB Device DiskDrive USBSTOR\DISK&VEN_SANDISK&PROD_CRUZER_EDGE&REV_1.20\200431108215FFF05367&0 USB Mass Storage Device USB USB\VID_0781&PID_556B\200431108215FFF05367

The "USB Mass Storage Device" has the correct VID, PID, SerialNumber, but the DiskDrive device does not. Linux targets see the same two devices (see below for lsusb & dmesg examples)

From the source, It looks to me like the vendor=”Linux” and model=“File-Stor Gadget” is being set in the function fsg_common_set_inquiry_string in f_mass_storage.c https://github.com/raspberrypi/linux/blob/rpi-4.19.y/drivers/usb/gadget/function/f_mass_storage.c

  • I would like to know the best way to override that behaviour (preferably without having to recompile f_mass_storage module every time!)?
  • Is there a way that the gadget could pass through iManufacturer, iProduct parameters to use as Vendor and Model?

The steps I used to create the Raspbian environment are: Clean flash Rasbian onto SD card using Balena Etch

sudo su echo "dtoverlay=dwc2" | sudo tee -a /boot/config.txt echo "dwc2" | sudo tee -a /etc/modules echo "g_mass_storage" | sudo tee -a /etc/modules sudo dd if=/dev/zero of=/home/pi/piusb_fat32.bin bs=1 count=0 seek=128M sudo mkdosfs /home/pi/piusb_fat32.bin -n FAT32VOL11 reboot now

I have tried:

  • On Windows, deleting the cached reg key for the device: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\usbflags\keyname Where keyname is the concatenation of VID+PID+BCD_RELEASE_NUMBER
  • Changing the serial number of the device each time I create the gadget, so eliminate caching as the cause.
  • Reformatting the USB disk from Windows, as Fat32, with a different volume name (rather than using mkdosfs)
  • Multiple versions of raspbian
    • 2019-09-26-raspbian-buster-lite (with & without running apt full-upgrade)
    • 2018-06-27-raspbian-stretch-lite (with & without running apt full-upgrade)
    • 2019-04-08-raspbian-stretch-lite (with & without running apt full-upgrade)

I’m certainly no USB or Linux expert, so this is what I have tried to piece together about how the Raspberry Pi USB ‘gadget’ Storage stack works. There are Five things of relevance:

  • dwc2 module (does the OTG host/gadget flip dictated by OTG_SENSE)
  • usb_f_mass_storage.ko module (Mass Storage Functions, handles the SCSI stuff to interface between USB & the file that acts as the storage for our USB disk)
  • g_mass_storage.ko module (The Mass Storage Gadget)
  • the file on the Pi that acts as the storage. this holds the filesystem and data that is read/writen to the emulated USB storage.
  • The parameters that we pass to g_mass_storage module when loading it via modprobe

There is a very similar post here, but it hasn’t been active for more than 2 years now, and it didn’t solve my issue, so I’m re-posting here with more info:

And someone else had the same problem, unresolved from 2017:

----On a Kali x86 Laptop: ----------

dmesg (output snipped to show relevant stuff) [66925.017786] usb 1-4.3: New USB device found, idVendor=0781, idProduct=556e [66925.017794] usb 1-4.3: New USB device strings: Mfr=3, Product=4, SerialNumber=5 [66925.017799] usb 1-4.3: Product: Cruzer Edge [66925.017804] usb 1-4.3: Manufacturer: SanDisk [66925.017808] usb 1-4.3: SerialNumber: 990431108215FFF05368 [66925.019129] usb-storage 1-4.3:1.0: USB Mass Storage device detected [66925.019542] scsi host3: usb-storage 1-4.3:1.0 [66926.021250] scsi 3:0:0:0: Direct-Access Linux File-Stor Gadget 0414 PQ: 0 ANSI: 2 [66926.022471] sd 3:0:0:0: Attached scsi generic sg1 type 0 [66926.023505] sd 3:0:0:0: [sdb] 262144 512-byte logical blocks: (134 MB/128 MiB) [66926.023729] sd 3:0:0:0: [sdb] Write Protect is off [66926.023736] sd 3:0:0:0: [sdb] Mode Sense: 0f 00 00 00 [66926.023932] sd 3:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [66926.034208] sdb: [66926.035170] sd 3:0:0:0: [sdb] Attached SCSI removable disk

------lsusb of RPi from kali --

root@kali:~# lsusb -d 0781:556e -v Bus 001 Device 031: ID 0781:556e SanDisk Corp. Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x0781 SanDisk Corp. idProduct 0x556e bcdDevice 1.03 iManufacturer 3 SanDisk iProduct 4 Cruzer Edge iSerial 5 990431108215FFF05368 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 32 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xc0 Self Powered MaxPower 2mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 8 Mass Storage bInterfaceSubClass 6 SCSI bInterfaceProtocol 80 Bulk-Only iInterface 1 Mass Storage Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x01 EP 1 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 1 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0000 (Bus Powered)

------- Kali's view of the USB Device from /sys/bus/usb ----

root@kali:~# cat /sys/bus/usb/devices/1-4.2/* cat: /sys/bus/usb/devices/1-4.2/ep_00: Is a directory 556e 0781 no SanDisk 0 cat: /sys/bus/usb/devices/1-4.2/port: Is a directory cat: /sys/bus/usb/devices/1-4.2/power: Is a directory Cruzer Edge 0x0 unknown cat: /sys/bus/usb/devices/1-4.2/remove: Permission denied 990431108215FFF05368 480 cat: /sys/bus/usb/devices/1-4.2/subsystem: Is a directory MAJOR=189 MINOR=29 DEVNAME=bus/usb/001/030 DEVTYPE=usb_device DRIVER=usb PRODUCT=781/556e/103 TYPE=0/0/0 BUSNUM=001 DEVNUM=030 426 2.00

----------How Kali see's the RPi SCSI vendor & model strings ---------

root@kali:~# cat /sys/bus/scsi/devices/target3\:0\:0/3\:0\:0\:0/vendor Linux root@kali:~# cat /sys/bus/scsi/devices/target3\:0\:0/3\:0\:0\:0/model File-Stor Gadget

-------- dmesg from Pi Zero after connecting to Windows -----------------

[ 409.446304] dwc2 20980000.usb: new device is high-speed [ 409.479146] dwc2 20980000.usb: new address 9 [ 439.684939] dwc2 20980000.usb: new device is high-speed [ 439.717958] dwc2 20980000.usb: new address 10 [ 439.748612] g_mass_storage gadget: high-speed config #1: Linux File-Backed Storage

Based on feedback from @Ephemeral (many thanks...). I have now tested using libcomposite and conclude it is the best answer.

The problem boils down to inquiry_string being unchangeable with g_mass_storage (unless you want to re-compile the module yourself with a different inquiry_string), but libcomposite gives full control of it, and many other parameters of the usb device.

One downside of libcomposite is that its not a one-liner to instantiate the gadget, it requires a bit more work. But after the gadget is created, the inquiry_string can be changed on the fly, which is quite cool! echo 'ABCDEFGH123456789ABCDEFGWXYZ' >> /sys/kernel/config/usb_gadget/gadget1/functions/mass_storage.usb0/lun.0/inquiry_string

inquirystring is tokenized by the host OS into: vendor(len 8) + model(len 16) + rev(len 4) which is what we see in Windows in PNPDeviceID as VEN_ PROD_ REV_

Name PNPClass PNPDeviceID ---- -------- ----------- SanDisk Cruzer Edge USB Device DiskDrive USBSTOR\DISK&VEN_SANDISK&PROD_CRUZER_EDGE&REV_1.20\200431108215FFF05367&0

and in OpenWRT Linux as vendor, model, rev in:

/sys/class/block/sda/device/vendor /sys/class/block/sda/device/model /sys/class/block/sda/device/rev

or x86 Kali Linux as vendor, model, rev in:

/sys/bus/scsi/devices/target3\:0\:0/3\:0\:0\:0/vendor /sys/bus/scsi/devices/target3\:0\:0/3\:0\:0\:0/model /sys/bus/scsi/devices/target3\:0\:0/3\:0\:0\:0/rev

I found this article quite useful to get a better understanding of the architecture of USB composite devices: https://lwn.net/Articles/395712/

This is the full script I use now:

#!/bin/bash # libcomposite USB mass storage device gadget for raspberry pi zero # Call this script on Pi Zero startup by adding its full path to /etc/rc.local # Assumes you have created the backing file for the storage device with something like this: # sudo dd if=/dev/zero of=/home/pi/piusb_fat32.bin bs=1 count=0 seek=128M # sudo mkdosfs /home/pi/piusb_fat32.bin -n FAT32VOL11 # And done these two steps once: # sudo echo "dtoverlay=dwc2" | sudo tee -a /boot/config.txt # sudo echo "dwc2" | sudo tee -a /etc/modules # Do some simple logging so we know the script is launching at startup date | tee -a /home/pi/startup_script.log echo Starting startup_script | tee -a /home/pi/startup_script.log #Load the kernel module modprobe libcomposite #Gadget name (gadget1 is just an arbitrary name) mkdir /sys/kernel/config/usb_gadget/gadget1 cd /sys/kernel/config/usb_gadget/gadget1 #hardware id echo 0x0419 > bcdDevice echo 0x0200 > bcdUSB echo 0x0781 > idVendor # Sandisk echo 0x556e > idProduct # Cruzer Edge #device config echo 0xEF > bDeviceClass echo 0x02 > bDeviceSubClass echo 0x01 > bDeviceProtocol echo 0x08 > bMaxPacketSize0 #More stuff mkdir strings/0x409 mkdir strings/0x407 cd strings/0x409 echo 'Sandisk' > manufacturer echo 'Cruzer Edge' > product echo 'Serial123456789' > serialnumber cd ../../ cd strings/0x407 echo 'Sandisk' > manufacturer echo 'Cruzer Edge' > product echo 'Serial123456789' > serialnumber cd ../../ mkdir functions/mass_storage.usb0 #Mass Storage 0 config settings cd functions/mass_storage.usb0 echo 0 > stall echo 1 > lun.0/removable echo 0 > lun.0/ro echo /home/pi/piusb_fat32.bin > lun.0/file #Note, the next line is important. Host OS will tokenize it as: vendor(len 8) + model(len 16) + rev(len 4) #Example here: vendor = ABCDEFGH model = 123456789ABCDEFG rev = WXYZ echo 'ABCDEFGH123456789ABCDEFGWXYZ' > lun.0/inquiry_string cd ../../ #OS Descriptor for Windows cd os_desc echo 1 > use echo 0xcd > b_vendor_code echo MSFT100 > qw_sign cd ../ #Bus Hardware Config mkdir configs/c.1 cd configs/c.1 echo 0x80 > bmAttributes echo 100 > MaxPower mkdir strings/0x409 echo "0" > strings/0x409/configuration mkdir strings/0x407 echo "1" > strings/0x407/configuration cd ../../ ln -s functions/mass_storage.usb0 configs/c.1 ln -s configs/c.1 os_desc #Activate the gadget ls /sys/class/udc > UDC

This is what it generates in dmesg on Kali x86:

[ 279.856039] usb 1-4.4: new high-speed USB device number 8 using xhci_hcd [ 279.957788] usb 1-4.4: New USB device found, idVendor=0781, idProduct=556e [ 279.957796] usb 1-4.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [ 279.957801] usb 1-4.4: Product: Cruzer Edge [ 279.957805] usb 1-4.4: Manufacturer: Sandisk [ 279.957809] usb 1-4.4: SerialNumber: Serial123456789 [ 279.978012] usb-storage 1-4.4:1.0: USB Mass Storage device detected [ 279.978128] scsi host3: usb-storage 1-4.4:1.0 [ 279.978232] usbcore: registered new interface driver usb-storage [ 279.979998] usbcore: registered new interface driver uas [ 280.989354] scsi 3:0:0:0: Direct-Access ABCDEFGH 123456789ABCDEFG WXYZ PQ: 0 ANSI: 2 [ 280.990460] sd 3:0:0:0: Attached scsi generic sg1 type 0 [ 280.990906] sd 3:0:0:0: [sdb] 262144 512-byte logical blocks: (134 MB/128 MiB) [ 280.991089] sd 3:0:0:0: [sdb] Write Protect is off [ 280.991095] sd 3:0:0:0: [sdb] Mode Sense: 0f 00 00 00 [ 280.991271] sd 3:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 280.999942] sdb: sdb1 [ 281.001878] sd 3:0:0:0: [sdb] Attached SCSI removable disk

And lsusb -vv on kali x86:

root@kali:~# lsusb -vv -d 0781:556e Bus 001 Device 008: ID 0781:556e SanDisk Corp. Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 239 Miscellaneous Device bDeviceSubClass 2 ? bDeviceProtocol 1 Interface Association bMaxPacketSize0 64 idVendor 0x0781 SanDisk Corp. idProduct 0x556e bcdDevice 4.19 iManufacturer 1 Sandisk iProduct 2 Cruzer Edge iSerial 3 Serial123456789 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 32 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 4 0 bmAttributes 0x80 (Bus Powered) MaxPower 100mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 8 Mass Storage bInterfaceSubClass 6 SCSI bInterfaceProtocol 80 Bulk-Only iInterface 5 Mass Storage Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x01 EP 1 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 1 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 239 Miscellaneous Device bDeviceSubClass 2 ? bDeviceProtocol 1 Interface Association bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0000 (Bus Powered)
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1 Answer 1

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The parameter is : inquiry_string, if this parameter is not defined the value is empty/null then : Linux File-Stor Gadget 0414 is used (where 0x0414 is the langage).More info here

After some research : (tree /sys/kernel/config/usb_gadget/mygadget when the gadget is activated) I have found an empty file named inquiry_string in functions/mass_storage.usb0/lun.0/ that I did not create in my conf. I use libcomposite.

You have :

[..] usb-storage 1-1.2:1.4: USB Mass Storage device detected [..] scsi host0: usb-storage 1-1.2:1.4 [..] scsi 0:0:0:0: Direct-Access Linux File-Stor Gadget 0414 PQ: 0 ANSI: 2

On Raspbian, when the UMS gadget is plugged without inquiry_string defined :

enter image description here

Using libcompiste :

New Configuration Adding inquiry_string:

mkdir -p functions/mass_storage.usb0 echo 1 > functions/mass_storage.usb0/stall # allow bulk EPs echo 0 > functions/mass_storage.usb0/lun.0/cdrom # don't emulate CD-ROm echo 0 > functions/mass_storage.usb0/ro # write access echo 0 > functions/mass_storage.usb0/lun.0/nofua # enable Force Unit Access (FUA) echo 1 > functions/mass_storage.usb0/lun.0/removable echo "ScanDisk" > functions/mass_storage.usb0/lun.0/inquiry_string

Now you have :

[..] usb-storage 1-1.2:1.4: USB Mass Storage device detected [..] scsi host0: usb-storage 1-1.2:1.4 [..] scsi 0:0:0:0: Direct-Access ScanDisk PQ: 0 ANSI: 2

Where ScanDisk can be anything.

Ref: f_mass_storage

Also you can set label name of your vfat : sudo mkdosfs -n "RASPBERRYPI" /vfat.fs.bin

Now on the host your device is recognized (when you click on top right of the desktop on the Remove icon on Raspbian :

ScanDisk Cruzer Edge (RASPBERRYPI)

enter image description here

"ScanDisk" → functions/mass_storage.usb0/lun.0/inquiry_string "Cruzer Edge" → strings/0x409/product "(RASPBERRYPI)" → volume label

Using g_mass_storage Mass Storage Gadget (MSG) :

sudo modprobe g_mass_storage --show-config|grep inquiry alias symbol:fsg_common_set_inquiry_string usb_f_mass_storage alias symbol:fsg_show_inquiry_string usb_f_mass_storage alias symbol:fsg_store_inquiry_string usb_f_mass_storage

And 

sudo modinfo g_mass_storage|grep parm|awk -F ':' '{print $2}' idVendor idProduct bcdDevice iSerialNumber iManufacturer iProduct file ro removable cdrom nofua luns stall

As you can see the parameters of module not contains any inquiry_string parameter but usb_f_mass_storage symbol contain some availables related functions.

In your case using g_mass_storage you must use:

sudo modprobe g_mass_storage file=/home/pi/piusb_fat32.bin nofua=1 luns=1 ro=0 stall=0 removable=1 cdrom=0 idVendor=0x0781 idProduct=0x556e bcdDevice=0x0103 iManufacturer="SanDisk" iProduct="Cruzer Edge" iSerialNumber="990431108215FFF05368"

And read this related paper.

Other then those, as usual, the values of module parameters can be
read from /sys/module/g_mass_storage/parameters/* files.

Then :

root@raspberrypi:~# modprobe g_mass_storage file=/home/pi/Desktop/usbdisk.bin nofua=1 luns=1 ro=0 stall=0 removable=1 cdrom=0 idVendor=0x0781 idProduct=0x556e bcdDevice=0x0103 iManufacturer="SanDisk" iProduct="Cruzer Edge" iSerialNumber="990431108215FFF05368" root@raspberrypi:~# echo test > /sys/module/g_mass_storage/parameters/inquiry_string -bash: /sys/module/g_mass_storage/parameters/inquiry_string: Permission denied root@raspberrypi:~# ls -l /sys/module/g_mass_storage/parameters/ total 0 -r--r--r-- 1 root root 4096 déc. 18 03:23 bcdDevice -r--r--r-- 1 root root 4096 déc. 18 03:23 cdrom -r--r--r-- 1 root root 4096 déc. 18 03:23 file -r--r--r-- 1 root root 4096 déc. 18 03:23 idProduct -r--r--r-- 1 root root 4096 déc. 18 03:23 idVendor -r--r--r-- 1 root root 4096 déc. 18 03:23 iManufacturer -r--r--r-- 1 root root 4096 déc. 18 03:23 iProduct -r--r--r-- 1 root root 4096 déc. 18 03:23 iSerialNumber -r--r--r-- 1 root root 4096 déc. 18 03:23 luns -r--r--r-- 1 root root 4096 déc. 18 03:23 nofua -r--r--r-- 1 root root 4096 déc. 18 03:23 removable -r--r--r-- 1 root root 4096 déc. 18 03:23 ro -r--r--r-- 1 root root 4096 déc. 18 03:23 stall

But as you can see the directory is ReadOnly, then you cannot set any parameters, only read parameters.

Maybe a solution can be found here.But here I can read :

...FSG's module parameters are not supported. ...

and remember you have:

alias symbol:fsg_common_set_inquiry_string usb_f_mass_storage

So, finally I think you cannot set the inquiry_string FS parameter if you not use libcomposite (libcomposite seems to create a NULL inquiry_string file then you can set any value in this file as my screenshots show very well)

And sorry for the typo , in my tests I use ScanDisk instance of SanDisk but it is not important.

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  • Thanks @Ephemeral - I have edited my original post now with more details at the end, and libcomposite is working well for what I need. many thanks. Commented Jan 15, 2020 at 8:21
  • @JayKay5532, Your'e welcome. Are you sure the echo 0x08 > bMaxPacketSize0 is really working ? Have you chefck this value after your gadget is running ? Commented Jan 15, 2020 at 9:15
  • @JayKay5532 thanks for all your work on this! One thing, how do you stop the mass storage? With the mass storage gadget it was just a case of sudo modprobe -rv g_mass_storage however trying either that with libcomposite or doing sudo echo "" > UDC just gives me a 'permission denied' (the same as if I try to change the inquiry_string on the fly as you suggest above? Commented Jan 16, 2020 at 0:03
  • 1
    @Ephemeral - you are correct - it looks like bMaxPacketSize0 stays at 64 (decimal) according to lsusb. I have posted the full lsusb and dmesg outputs that I see. But it certainly doesnt give me any error when I echo the value to bMaxPacketSize0 or inquiry string. Commented Jan 16, 2020 at 8:23
  • 1
    @EDIflyer : cd /sys/kernel/config/usb_gadget/GADGETNAME then 1 - unbound driver configfs-gadget : sudo bash -c 'echo > UDC', 2 - Remove symbolic link of the UMS configuration : sudo bash -c 'rm -R functions/mass_storage.usb0 configs/c.1/', 3 - bound driver configfs-gadget : sudo bash -c 'ls /sys/class/udc > UDC' should work. This remove the UMS conf and rebound the gadget for activate others gadget modes (keyboard, serial etc...). For deactivate all : sudo bash -c 'echo > UDC' Commented Jan 16, 2020 at 9:54

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