Re: Regarding the ULTRIX and OSF1 compats

[Jason Thorpe <thorpej%me.com@localhost>]

> On Mar 10, 2019, at 4:16 AM, Maxime Villard <max%m00nbsd.net@localhost> wrote:
> 
> Le 10/03/2019 à 11:25, Björn Johannesson a écrit :
>> Hello.
>> 
>> COMPAT_ULTRIX (mips) works fine which I recently discovered after shuffling
>> some disks and NetBSD8 mounted the ULTRIX disk as /
> 
> This more likely means that it was an old UFS disk that we do support by
> default in our UFS/FFS code, but I hardly see how this could be related to
> COMPAT_ULTRIX.

No, I'm sure he actually means an old Ultrix disk.  Doing that sort of thing was quite common back in the early NetBSD days.  NetBSD/pmax supports the DECstation disk label format because that's what the boot ROM understands, and the NetBSD can read/write the Ultrix UFS because it's vanilla 4.3BSD.

> Which MIPS are you talking about by the way? Pmax I guess? Because
> COMPAT_ULTRIX is disabled on the majority of our MIPSs.
> 
>> Not that I have terribly much use for it (except maybe maple) but I would
>> still like it to be kept in.
> 
> I would tend to think that a good reason needs to go a bit farther than just
> "I'd like to keep it in"...

Like I said, COMPAT_ULTRIX is a very thin veneer over just a few native system calls.  I think it might even be less complex than COMPAT_SUNOS.  The vast majority of the COMPAT_ULTRIX system call table points directly either to native system calls or to COMPAT_43 veneers of native system calls.  The COMPAT_43 calls are quite well maintained, because they're required for several early flavors of COMPAT_NETBSD*.

> When it comes to Maple, it is already available on Linux, and we do have
> COMPAT_LINUX.
> 
> In fact, nowadays, the vast majority of proprietary binaries compiled on
> UNIX-like systems are available on Linux, and we do support Linux emulation,
> so we're covered for the most part.

...while that may be true, if an old Ultrix version is working for him, why not let it continue to work?  As I said, the maintenance burden for COMPAT_ULTRIX is not nearly as high as for some of the others, and for some of those others, people weren't even actively using them.  Here was have an example of a not-complicated COMPAT module being actually used out in the wild, so I don't think it's reasonable to remove it.

-- thorpej