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Re: usb_keyboard not available as a terminal input?

From: Tom Yan
Subject: Re: usb_keyboard not available as a terminal input?
Date: Sun, 21 May 2017 17:28:17 +0000

So I assume there is no way to use usb_keyboard on 6th Gen or later Intel 
platforms, because there is not an xhci driver in grub while EHCI is completely 
gone from their PCH?

I tried `insmod ehci` anyway. Interestingly, the grub environment is sort of 
broken after that, because the disk is gone after the insmod command. Like, 
before that if I `ls`, it shows "(hd0), (hd0, gpt1), (hd0, gpt2), (hd0, gpt3)"; 
and after that if I `ls`, it prints a blank new line. (I am on a system that 
has one single drive which is a USB drive).

It seems to me like if I load ehci, the current host controller driver is 
replaced so grub can no longer see the USB drive it is on. However there is not 
an "xhci" module, so I wonder what was being replaced.

And if my assumption is true, why would usb_keyboard not work while the storage 
drive works?

From: Andrei Borzenkov <address@hidden>
Sent: Monday, May 22, 2017 12:36 AM
To: Tom Yan; address@hidden
Subject: Re: usb_keyboard not available as a terminal input?
21.05.2017 18:18, Tom Yan пишет:
> Hi all.
> So I happened to have looked into terminal_input for a bit (that is, 
> "console", the default, has always worked for me so far. I just look into it 
> because of curiosity and possible future use case). I notice that there 
> should be a "usb_keyboard", as documented  here:  

GNU GRUB Manual 2.02: Simple configuration

While adding extra custom menu entries to the end of the list can be done by 
editing /etc/grub.d/40_custom or creating /boot/grub/custom.cfg, changing the 
order of menu entries or changing their titles may require making complex 
changes to shell scripts stored in /etc/grub.d/.

The file /etc/default/grub controls the operation of.  grub-mkconfig.  It is 
sourced by a shell script, and so must be valid POSIX shell input; normally, it 
will just be a sequence of ‘KEY=value’ lines, but if the value contains spaces 
or other special characters then it must be quoted.">6.1 Simple configuration 
handling. The program grub-mkconfig (see Invoking grub-mkconfig) generates 
grub.cfg files suitable for most cases. It is suitable for use ...
> However, when I run `terminal_input` in the grub shell, I see this:
> Active input terminals:
> console
> Available input terminals:
> serial_* serial at_keyboard
> And usb_keyboard is missing.
> I tried `insmod usb_keyboard` and `terminal_input` again; while `lsmod` lists 
> usb_keyboard, terminal_input still doesn't list it as an available input 
> terminal.

This means usb_keyboard did not detect keyboard. You need to load
suitable HCI drivers as well (ohci, ehci, uhci) - otherwise usb_keyboard
has no way to communicate with device.

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