Re: [grub 2.02 help] not a valid root device

[Andrei Borzenkov]

11.05.2017 06:20, 人墙 пишет:
> hi!
> i have a problem:
> when i start up the grub 2.02,my usb device are identified as efi 
> device:(hd1,msdos1); At this time,i chainloader ,it is correct,and the winPE 
> system can be started up!
> 
> Then i use the command [nativedisk] to drive it to usb,then the usb device 
> drived as usb SCSI device:(usb0a,msdos1);
> The question is: at this time when i chainloader ,it is not correct, and 
> tip[not a valid root device].
> 
> How to solve this problem?

You cannot, this is by design. chainloader requires native firmware disk
device and nativedisk command disables them.

> or how can i drive my usb device again to efi device?

Again, you cannot. nativedisk loads drivers that bypass firmware and
modify hardware state directly. After this happened, we cannot go back
to firmware, it will be in undefined state.

Somebody intended to work on USB handoff support, this may help in this
case. Until this is available, the only way is to reboot.