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

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

The following reply was made to PR port-i386/57641; it has been noted by GNATS.

From: Taylor R Campbell <riastradh%NetBSD.org@localhost>
To: matthew green <mrg%eterna.com.au@localhost>
Cc: Andrew Doran <ad%netbsd.org@localhost>, gnats-bugs%netbsd.org@localhost,
	port-i386-maintainer%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
	netbsd-bugs%netbsd.org@localhost, Andreas Gustafsson <gson%gson.org@localhost>
Subject: Re: port-i386/57641: -current/i386 no longer installs in 32 MB
Date: Sat, 7 Oct 2023 11:57:17 +0000

 > Date: Sat, 07 Oct 2023 15:51:34 +1100
 > from: matthew green <mrg%eterna.com.au@localhost>
 >=20
 > Andrew Doran writes:
 > > On Wed, Oct 04, 2023 at 10:50:25PM +0000, Taylor R Campbell wrote:
 > >
 > > > > From: Andrew Doran <ad%netbsd.org@localhost>
 > > > >=20
 > > > > It's probably not an satisfying answer but I don't think it's a val=
 id test
 > > > > because DIAGNOSTIC uses a lot more memory and we shouldn't be shipp=
 ing
 > > > > actual release kernels with it enabled.
 > > >=20
 > > > 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.
 >=20
 > 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?