Re: 100% CPU usage while waiting for LUKS password

[James Harvey]

On Wed, Jun 26, 2019 at 8:10 PM James Harvey <address@hidden> wrote:
>
> While waiting for the user to type a LUKS password, grub 2.0.2 causes
> 100% CPU usage.
>
> This is perhaps most problematic within a virtual machine, taking up
> an entire virtual core on the host.  Especially bad for VM providers
> who don't have control over this.
>
> This is certainly a lesser problem on bare metal, although it's never
> a great idea to put undue stress on hardware.

Found what's causing the 100% CPU usage.  12 years ago, 0149ab7c6
disabled the 'hlt' instruction in
include/grub/i386/time.h::grub_cpu_idle(), noting "this can't work
until we handle interrupts."  This later made its way into
include/grub/x86_64/time.h as well.

Has the missing interrupt support been added in the last 12 years, at
this stage in the boot process?