Re: Boot windows on external disk : "not a valid root device"

["Hervé Guillemet" <herve@guillemet.org>]

Le 02/01/2013 02:18, Vladimir 'φ-coder/phcoder' Serbinenko a écrit :
> On 02.01.2013 02:05, Hervé Guillemet wrote:
> 
>> Le 02/01/2013 01:33, Vladimir 'φ-coder/phcoder' Serbinenko a écrit :
>>> On 02.01.2013 01:14, Colin Watson wrote:
>>>
>>>> On Wed, Jan 02, 2013 at 12:31:14AM +0100, Hervé Guillemet wrote:
>>>>> I have a new Asus N56VZ laptop and replaced the Windows hard drive by a
>>>>> SSD with Linux installed. EFI Grub2 successfully launchs Linux.
>>>>> Now I'd like to boot Windows from the original hard drive mounted by USB.
>>>>>
>>>>> No matter what I try, either using grub.cfg or command line, Grub's
>>>>> chainloader fails :
>>>>>
>>>>>> set root=(usb0,gpt1)
>>>>>> chainloader ($root)/EFI/Microsoft/Boot/bootmgfw.efi
>>>>> Error: not a valid root device.
>>>>>
>>>>> The content of the drive may be seen using "ls".
>>>>>
>>>>> What's the exact meaning of "not a valid root device" ?
>>>>
>>>> It indicates that either no UEFI device handle corresponding to that
>>>> device was found, or that no UEFI protocol interface is available for
>>>> that device handle.  In other words, "can't work out how to talk to that
>>>> device using UEFI".
>>>>
>>>> I think your device naming is dubious: as far as I can see, GRUB's
>>>> efidisk module does not fully support calling a disk "usb0".  The "ls"
>>>> command should show you the list of available disks and partitions, or
>>>> you can type "set root=(" and then use tab-completion.  If the disk is
>>>> truly only accessible as "usb0", then perhaps efidisk needs some work to
>>>> support that.
>>>>
>>>
>>> Other than loopback, all devices follow the naming scheme insluding type
>>> prefix as detailed in manual. "usbN" means that the device is accessed
>>> using GRUB own modules. To use chainloader on EFI you have to avoid
>>> loading any USB modules and use hdX names.
>>
>> Ok, I tried, but then the external disk is not visible and ls only shows
>> me hd0. Can you see a possible solution ?
>>
> 
> It probably means that EFI doesn't see you USB disk. Be sure that it's
> connected on poweron and be sure to use recent GRUB. If still doesn't
> help look if it's seen through EFI shell.
> For using chainloader you need disk to be visible through EFI, otherwise
> bootmgfw.ef won't be able to find rest of the files.
> If the EFI doesn't see the USB disk in shell and/or in boot device
> selection you should contact your manufacturer.
> 

EFI shell did not see it.
However, after turning on some "Legacy USB support" option in the
BIOS/UEFI setting, it does, as well as Grub using (hd0,gptX) !
Windows has not appreciated to be relocated at the end of a USB cable
though, but it's another story.
Thanks to you 3 for yours answers and help,

-- 
Hervé