Re: [PATCH v2] i386: Make 'hv-reenlightenment' require explicit 'tsc-frequency' setting

[Eduardo Habkost]

My apologies, this was lost under the noise in my mail inbox.
(I promise I'm trying to improve)

On Wed, Mar 31, 2021 at 01:39:48PM +0200, Vitaly Kuznetsov wrote:
> Commit 561dbb41b1d7 "i386: Make migration fail when Hyper-V reenlightenment
> was enabled but 'user_tsc_khz' is unset" forbade migrations with when guest
> has opted for reenlightenment notifications but 'tsc-frequency' wasn't set
> explicitly on the command line. This works but the migration fails late and
> this may come as an unpleasant surprise. To make things more explicit,
> require 'tsc-frequency=' on the command line when 'hv-reenlightenment' was
> enabled. Make the change affect 6.0+ machine types only to preserve
> previously-valid configurations.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Even if the 6.0 release gets delayed, I wouldn't be comfortable
including this in a -rc4.

What if the user does not plan to live migrate the machine at
all?  Why is this case different from the ~25
migrate_add_blocker() calls in QEMU, where we block migration but
still let the VM run?

-- 
Eduardo