By the way - I might have been a little confused in my previous reply.
I thought we had bad sectors also in the disklabel, but we don't. So
ignore that bit. But we do have the replacement sectors. I guess that's
what you want to get out, right?
Also, the bad144 program is honestly somewhat broken, if we're talking
about the DEC STD 144 bad sector handling. What we have in bad144 sortof
works, but it's not correct or complete.
There are actually two lists of bad sectors as specified by DEC STD 144.
Manufacture marked bad sectors, and field marked bad sectors. And they
are kept in two different areas.
But that is getting somewhat off topic here. In general, I agree that
this should only exist for machines where it makes sense. Not sure how
to go about that in a good way, though.
Johnny
On 5/27/26 14:00, Jason Thorpe wrote:
I am on a quest to properly unify the m68k user-land, which means addressing
some long-standing ABI differences in some of the darker corners ofthe system.
One particularly dark corner is BSD disklabel handling, which, from where I
sit, is a giant toxic dumpster fire raging in the middleof the Bog of Eternal
Stench. But I don’t have time for that rant this morning.
So, let’s focus on DEC STD 144, a.k.a. bad144, a.k.a. dkbad. It’s a 1970s-era
bad sector remapping scheme that was already mostly obsolete by the mid-80s
(ever since SCSI drives were able to maintain their own bad sector remapping
information). It is totally and completely useless on any drive made since the
1990s. And yet, its tendrils infest many a NetBSD port’s BSD disklabel
handling because, as far as I can tell, cargo-cultism.
I figure there are a handful of legit use cases for bad144 in NetBSD still:
- The vax port, obviously, but only with the really old drives. (VAX peeps
please help me out here - is bad144 useful drives behind an MSCP-compliant
controller?)
- hp300 port maybe (for HP-IB drives).
- sun3 / sun4 (Xylogics controllers and SMD drives)
- i386 (ESDI, ST506, other ancient drive technologies that can plug into ISA or
MCA)
What I would like to propose is that bad144 be completely decoupled from
“disklabel” and refactored out as set of library routines (slash module) that
drivers can use. But, most importantly, get it out of the main “BSD disklabel”
code path.
And so, let’s discuss.
-- thorpej
