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Re: Problem with USB keyboard + ehci.mod

From: Andrey Borzenkov
Subject: Re: Problem with USB keyboard + ehci.mod
Date: Mon, 28 Apr 2014 19:59:52 +0400

В Mon, 28 Apr 2014 17:25:57 +0200
Richard Foltyn <address@hidden> пишет:

> Dear listers,
> I have a USB hub/switch (ATEN US224) to share a USB keyboard / mouse
> between two computers.
> On one of these computers, the keyboard in the grub2 menu works only
> if I pre-load ehci.mod (independent of whether "legacy USB support" is
> enabled in BIOS or not).
> However, as soon as I load ehci.mod, the partitions present on the
> hard drive are no longer seen by grub2's ls

Yes; loading ehci explicitly disables native (BIOS) disk driver.

>                                            and I can no longer boot
> into Windows (Linux still works since it resides on LVM).
> I.e., BEFORE loading ehci, ls on the grub2 command line shows something like
> (hd0) (hd0,msdos1) (hd0,msdos2)  + some LVM volumes
> AFTER I load ehci I see
> (usb0a) (usb0b) (usb0c) (usb0d) + some LVM volumes

"some LVM volumes" is actually minor cosmetic bug here, but I'm not
sure how difficult it is to track all references.

I'm afraid this does not have easy solution. As I understand, native
driver is disabled because driver tells BIOS to relinquish USB control
and we do not know what is controlled - it could as well be hard disk
or other mass storage and we lose access to it (or worse crash system
when accessing it).

What you could try - try loading ahci driver (better via "nativedisk"
command if your version supports it - it will also load ehci among
others). Thus you will hopefully get native access (not via BIOS) to
the same disk.

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