On Thu, 2015-10-22 at 12:08 -0700, Geoff Levand wrote: > 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. For me it was beyond "notice the difference" -- I thought it was completely broken, and was preparing to debug, until it started spitting out output over a minute later. Compiling the sha256 code with -O2 instead of -O0 cut it down to around 10 seconds (still unpleasant, but not quite as crazy... still unacceptable for non-kdump, though). There was a patch posted a couple years ago to do that -- does anyone know what happened to it? http://kexec.infradead.narkive.com/JSemzXoT/patch-purgatory-compile-sha256-c-only-on-ia64-with-o0 -Scott
