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

From: Andrei Borzenkov
Subject: Re: USB devices non-functional when chainloading Windows 7 from GRUB
Date: Sat, 14 Jan 2017 11:03:54 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1

13.01.2017 13:52, Will Thompson пишет:
> Hi,
> A user has reported that, after they set up Endless OS to dual-boot with
> Windows 7, their keyboard and mouse no longer work in Windows, though they
> work fine in our Linux distro. This is a BIOS system. There's nothing
> particularly fancy in our GRUB 2 config for the Windows boot path: we just
> chainload the bootable partition. lsusb output shows that they have a USB 3
> controller (which is not supported out of the box in Windows 7, AIUI) but
> that their keyboard and mouse are attached to a USB 2 controller.
> There are a few reports around the internet of this issue. One thread[1] I
> found suggests that disabling Windows' driver verification helps; another
> thread[2] suggests installing a USB controller driver update. But in both
> cases, the controller worked fine when GRUB was not part of the boot path,
> so I'm wondering whether GRUB is leaving the controllers in some different
> state.
> Have you heard reports of this issue?


> Any idea what's going on?

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.

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.

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