Re: KASLR kernel fails to boot

[Maxime Villard <max%m00nbsd.net@localhost>]

Le 05/05/2020 à 21:01, Chavdar Ivanov a écrit :
> On Mon, 4 May 2020 at 21:21, Chavdar Ivanov <ci4ic4%gmail.com@localhost> wrote:
> > Hi,
> >
> > netbsd-GENERIC_KASLR from yesterday fails to pass the prekern stage
> > with a frightening message in red 'Page fault'. I've never seen this
> > before, no idea if I can get any further info.
> >
> > This machine has been otherwise running KASLR kernel for some four
> > months now without a problem; it is a VirtualBox guest.
>
> Same with just completed clean buid of 9.99.60.
>
> After "[+] Rel relocations applied" I get:
>
> ****** Fault occurred ******
> page fault
> ******************************
>
> I switched th vm to the normal kernel, no problem otherwise.

I know, this is because of the Xen section in the binary, which is not
marked as allocatable. The prekern explicitly decides not to map the note
but then proceeds to relocate its RELAs regardless, which causes a fatal
page fault.

Trivial to fix but I'm not sure which policy to choose, may take a few
days.