Re: [Qemu-devel] [PATCH 3/5] x86: fill high bits of mtrr mask

[Paolo Bonzini]

On 17/06/2016 15:41, Eduardo Habkost wrote:
> In theory, we should never initialize anything on the machine
> based on the host we are running. In practice we sometimes do
> that, and we know it's unsafe. Sending the value on the migration
> stream is a solution to detect when this breaks something. We did
> that before, for TSC frequency.
> 
> I prefer to add a little extra code, than to waste time debugging
> when that stuff breaks.

Fair enough (but still let's add and strip the 1s in pre_save and
post_load).  It is a good justification for sending configuration over
the wire, that we initialize things based on the host we're running.

But we shouldn't initialize more things based on the host (e.g. new
booleans should be "enforce"-style).  Also I don't really like
introducing sanity checks for those that aren't based on the host (as in
the LMCE thread).  This code will never trigger in practice, so it's
just extra cost for no benefit.

Paolo