USB bulk transfert from GRUB ?

["Nicolas de Pesloüan" <nicolas.2p.debian@gmail.com>]

Hi,

Some USB devices require a specific command to be sent (using USB bulk transfer) before they switch
to "storage mode". Such devices are switched by USBmodeSwitch
(http://www.draisberghof.de/usb_modeswitch/), after the operating system start. USBmodeSwitch use
libusb to send the right command to the right USB endpoint, depending on the ID of the USB device.

In order to be able to boot from such devices, one needs to switch the device early, before the 
operating system is started. I think GRUB2 should be the right place for this.

For as far as I understand, libusb is available from inside GRUB2, so it shouldn't be really 
difficult to add a command to initiate a given bulk transfert to a given USB endpoint. (My 
understanding is that no such command already exists).

Contrary to USBModeSwitch that use a database at runtime to decide how to switch the device, it is 
probably easier to decide this at grub-mkconfig time, using the same database.

Of course, I perfectly understand that the first part of GRUB2 cannot be located from this kind of 
USB devices, because it needs to be loaded before GRUB2 start, and we would face a chicken and egg 
problem.

Any comments ?

	Nicolas.