Re: port-i386/57641: -current/i386 no longer installs in 32 MB

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

> Date: Sat, 07 Oct 2023 15:51:34 +1100
> from: matthew green <mrg%eterna.com.au@localhost>
> 
> Andrew Doran writes:
> > On Wed, Oct 04, 2023 at 10:50:25PM +0000, Taylor R Campbell wrote:
> >
> > > > From: Andrew Doran <ad%netbsd.org@localhost>
> > > > 
> > > > It's probably not an satisfying answer but I don't think it's a valid test
> > > > because DIAGNOSTIC uses a lot more memory and we shouldn't be shipping
> > > > actual release kernels with it enabled.
> > > 
> > > How much more memory?  DIAGNOSTIC is supposed to be reasonably cheap,
> > > mostly cheap predicted-not-taken branches in assertions.
> >
> > There's not an easy formula for that.  kmem adds sizeof(size_t) to every
> > allocation to track that size allocated is the same as size freed, which
> > eats a lot more space than expected because alignment requirements (for
> > cache friendliness) still need to be met.
> 
> while i agree it may not be true to the "reasonably cheap" rule,
> i think that the damage caused by wrong kmem_free() size is far
> too dangerous to push this to only DEBUG.

Is this 32MB i386 failure a new regression?  Did it work with
DIAGNOSTIC and non-DIAGNOSTIC kernels alike before?