I have successfully gotten Kali to boot on the RPI4 4GB using USB only. To get it working, what you need to do is:


1) Download most recent Kali linux for RPI4 at https://www.offensive-security.com/k...ux-arm-images/


2) Flash the image to a usb drive (USB SSD is nice, but any usb drive compatible with the RPI4 will work)


3) Modify the cmdline.txt to be as follows:


Code:
dwc_otg.fiq_fix_enable=2 console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty1 root=/dev/sda2 rootfstype=ext3 rootwait rootflags=noload net.ifnames=0
4) You must mount the root file system on a computer. If someone can find a better way of doing this, or a better process overall, please post it. You need to edit the fstab file to change the mounting points of the root directory and boot partition.


Once the file system has been mounted on your computer (ie the larger partition of the usb drive that you just imaged), open the etc/fstab file, and edit it to look like this:


Code:
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    defaults          0       0
/dev/sda1  /boot           vfat    defaults          0       2
/dev/sda2  /               ext3    defaults,noatime  0       1
5) Format an SD card, and leave it with an empty ext3 partition. Insert this SD card into the raspberry pi for the initial boot. If you do not do this you will get an error stating that MMC0 timed out.


6) Boot up, and let it run its course. Once you get to the login, the default user is kali and the password is also kali.


7) Update the system, and shutdown. Now you can remove the SD card, and you are good to go with Kali booting off just USB.


For whatever reason, and I am sure someone smarter than me will know, or can figure it out, but Kali on the RPI4 is looking for an SD card on the initial boot. I vaguely remember that USB booting on the RPI3b+ also required you to have an SD card present.


Please enjoy


If someone finds something that breaks this, please let me know. So far, I am several hours running and 2 updates, as well as several application installs, and there are no issues. It doesn't run as fast as I was hoping it would, but hey, its booting off USB 3, so I'll take it.