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Re: usb keyboard not functional in non-uefi mode

From: Jan Gregor
Subject: Re: usb keyboard not functional in non-uefi mode
Date: Thu, 11 Feb 2016 09:49:16 +0000

Yes, it didn't worked in slax livecd until linux kernel was started. I also experienced same in debian installer until I disabled csm in bios that turns on uefi mode.

I'm aware of legacy usb support in bios and it is enabled.

The problem can be that microsoft natural keyboard is visible as two usb hid devices and the bios has somehow broken support for non-uefi case via bios services.

Well, I didn't expect that native usb drivers makes booting of windows impossible.


On Thu, Feb 11, 2016 at 10:24 AM Andrei Borzenkov <address@hidden> wrote:
On Thu, Feb 11, 2016 at 12:04 PM, Jan Gregor <address@hidden> wrote:
> Hello,
>   my keyboard (microsoft natural 4000) doesn't work in boot managers

Do you mean it also does not work in other boot managers, not only GRUB?

> although it is functional in bios, windows, linux and uefi mode.
> Unfortunatelly my disk works in mbr mode so uefi is not option for me. The
> keyboard worked ok with old computer so I think the problem relates to my
> current motherboard (asus p9dws).
>  I use grub2 from fresh debian installation (jessie), version
> 2.02~beta2-22+deb8u1.
>  Without modifications, grub2 boots without problems debian and windows 10.
> Unfortunately due to unfuctional keyboard I have to externally change
> default option.
>  When I added following lines to start of grub.cfg, my keyboard works.
>     nativedisk
>     insmod usb
>     insmod usb_keyboard
>     insmod ehci
>  Unfortunatelly boot of windows 10 ends with following error message
>    A disk read error occured. Press Ctrl + Alt + Del
> I think the error can relate to usb support that forces grub to use
> nativedisk module. Can you recommend how to solve booting of windows 10 in
> this case ?

No, you cannot chainload Windows once you tainted system with native
USB drivers. But the real question is why keyboard does not work. GRUB
is using BIOS services to perform input/output and you say it works in
BIOS setup, correct? It sounds like BIOS stops USB support when it
boots something. Try playing with BIOS setup options, in particular
"Legacy USB Support"; according to documentation if it is disabled,
then "USB devices can be used only for the BIOS setup program".

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