Re: CVS commit: src/sys/kern

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Mon, Dec 03, 2018 at 07:27:11PM +0000, Christos Zoulas wrote:
> In article <20181203183537.GA1562%antioche.eu.org@localhost>,
> Manuel Bouyer  <bouyer%antioche.eu.org@localhost> wrote:
> >On Mon, Dec 03, 2018 at 12:54:26PM +0100, Maxime Villard wrote:
> >> In other words, 80% of KASLR is enabled by default, regardless of #ifdef
> >> KASLR. Therefore, it is wrong to add an ifdef, because in either case we
> >
> >So there's no way to completely disable KASLR now ?
> >Although I admit it's usefull to have it on by default, there should be a way
> >to turn it off for low-level debugging
> 
> I don't think that the things that KASLR randomizes by default are useful
> to debugging. I.e. you can't depend on two successive kernel crashes to
> have identical PTE addresses; OTOH you can depend that the text addresses
> are the same (which are for GENERIC and are not for GENERIC_KASLR).

It depends at which time it crashes; if early in boot (before things
start executing in parallel) I would expect 2 runs to produce the same
thing in memory. 

One enough is set up to have ddb functional, KASLR is less of an issue.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--