Re: USB devices non-functional when chainloading Windows 7 from GRUB

[Andrei Borzenkov]

16.01.2017 16:47, Will Thompson пишет:
> On 14/01/17 08:03, Andrei Borzenkov wrote:
>> Not really. GRUB does not touch USB at all unless explicitly told to do
>> so by switching to native drivers or attempting to use USB
>> keyboard/mouse. It is possible that BIOS puts USB in some state that
>> *does* require payload to do something.
> 
> Does "attempting to use USB keyboard" include invoking "keystatus"? We
> don't explicitly load "usb" or "usb_keyboard" so my assumption is that
> this is going through i386/pc/console rather than usb_keyboard, but
> perhaps I'm wrong?
> 

keystatus should not load USB by itself, it queries currently loaded
drivers only.

>> There were discussions regarding USB handoff for xHCI. As you have USB3
>> this may be related. Let me look ... OK, subjects are
>>
>> EHCI handoff & AMI BIOS EHCI Handoff support.​
>> [PATCH]: xHCI/EHCI - Windows - BIOS bug interaction
>>
>> and more recent
>>
>> xHCI driver
>>
>> although the second one deals with opposite situation - keyboard does
>> not work in GRUB after reboot from Windows.
> 
> Thanks, these are some useful pointers. I don't have physical access to
> the affected machine so we are at the mercy of the user when it comes to
> trying possible workarounds. I'll report back if we find anything
> actionable, and/or whether the user can shed any light on the exact
> combination of devices and BIOS settings which lead to this situation.
> 
> – Will
> 
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