Porteus

I have found that on some hardware, booting Porteus from a USB 3 drive is not working very reliably, and so I'd like to be able to disable USB 3 support in the linux kernel. But I don't really want to have to rebuild the kernel to get there, if I can avoid it.

I've figured out where to put kernel command-line parameters, but I can't find a parameter that actually keeps the USB ports running at 2.0 speeds when you have a 3.0 drive in them.

I've tried:

modprobe.blacklist=xhci_hcd

and I've tried:

xhci_hcd.blacklist=yes

and in both cases confirmed they were there with 'cat /proc/cmdline' yet the xhci_hcd driver was loaded anyway, and lsusb -t confirms that the drives are running at full, flaky 3.0 speed.

Any suggestions?

Can you disable usb3 via the bios? It should continue to work but with usb2 speeds.

you can use a short USB 2 extension cable to connect the device.
This forces the USB 3 port to use USB 2 signalling.
A USB 3 device or cable has 9 pins, whereas a USB 2 device or cable only has 4 pins.
A USB 3 port will default to USB 2 signaling communication when only 4 pins are connected.
This way you wouldn't lose the ability to connect other USB 3 Devices to operate at full speed.