[PATCH] kexec: Add --lite option

[Geoff Levand]

Hi Vivek,

On Thu, 2015-10-22 at 08:50 -0400, Vivek Goyal wrote:
> On Thu, Oct 22, 2015 at 11:17:18AM +0800, Dave Young wrote:
> > On 10/21/15 at 04:12pm, Geoff Levand wrote:
> > > Add a new option --lite to kexec that allows for a fast reboot
> > > by avoiding the purgatory integrity checks.  This option is
> > > intended for use by kexec based bootloaders that load a new
> > > image and then immediately transfer control to it.
> > 
> > I think Vivek was rejecting this --lite since kdump need the purgatory
> > integrity checks. Ccing him.
> 
> Right. Why are we trying to bypass sha256 hash verification of loaded
> segments at run time, that needs to be justified. 

Please see my reply to Dave.

> Atleast on x86, this integrity verification was fast and we did not
> notice any siginificant delays in purgatory. And in that case extra knob
> like this is hard to justify.

I notice the difference on the my arm64 system, so I guess we
are even on that.

In general, faster boot times are desirable.  This option allows
a faster system boot for kexec based bootloaders that use
kexec-tools.

-Geoff