early x86 microcode loading

[Mark Johnston]

On Fri, Jul 13, 2018 at 11:05:30PM +0000, Poul-Henning Kamp wrote:
> --------
> In message <20180712224631.GF15892 at raichu>, Mark Johnston writes:
> 
> >I can think of three ways to address this case:
> >
> >1a) Always load all of the updates as a single file, and select the
> >    correct update during boot.  As I pointed out, this wastes some
> >    memory (a couple of megabytes currently).  On at least amd64 it
> >    doesn't look very practical to release the pages backing the
> >    update file back to the VM.  That is, I don't think we can easily
> >    "shed" the preloaded file data once the correct update has been
> >    selected and saved.
> 
> Then we should fix that problem, rather than build an elaborate
> workaround for in each and every subsystem which runs into this.

I implemented this in r336505 and plan to use it for the microcode
update file.

> Isn't this the same issue with the splash-screen for instance ?

I didn't look into the splash screen code, but it can be made to
give memory back to the system by using preload_delete_name().