dmesg submission service -- please submit today

Warner Losh imp at
Sun Oct 7 18:20:38 UTC 2018

On Sun, Oct 7, 2018 at 11:11 AM Roderick <hruodr at> wrote:

> On Sat, 6 Oct 2018, Warner Losh wrote:
> > As you can tell, the project is looking to clear some of the deadwood
> from
> > its driver lists. One problem is that we have to guess what's in used
> based
> > on our personal experience. This has proven to be less reliable than
> hoped
> > in the 10/100 discussions that are going on now.
> Should I dump a dmesg with any device I have connected to every computer
> I have? Deadline today?
> Or better I risk not be able to read data on old SCSI discs I am not
> using now?

There's no deadline, per se. And there will be at least two drivers that
will survive the purge (ahc and mpt). At the present time, they are the
only two known to be working for real workloads. So chances are you are
already using one of these devices, and if not they are cheap, so there
will be a fallback to getting data off of parallel SCSI disks, as well as
continued support for parallel scsi tape drives, scsi CD, etc. FreeBSD will
support a way to access these devices for years to come.

The reason I'm looking at this is because CAM has become rather twisted in
places over the years. Many of the reasons for the twistiness can be traced
directly to weird workarounds for devices that are almost certainly no
longer in use. I'd like to eliminate them. Some can be eliminated because
they were for a particular ISA device that's no longer in the tree. But I
can't do the others until I know which ones, if any, need to remain. This
is why I was asking for dmesgs now so I can start to get a feel for which
devices are even still in use on any FreeBSD version, let alone more modern
ones. Looking at the NIC data it's clear that we have devices that are
wildly popular, and then ones that aren't used with very little in between.
Unlike in NIC land, there's a more real and tangible cost that I can point
to for continuing old devices in the tree, and I said 'about a month from
now' so I can come up with examples of what's a problem, as well as look at
data to see what devices still have users, etc, to avoid some of the
back-and-forth that we had at the start of the 10/100 discussions as people
with devices that turned out to be popular rightly complained. I think
having a well articulated reason other than 'it's old' will also help the
community understand the cost of keeping things in the tree so we can
better judge of the current level of 'benefit' justifies that cost. And any
elimination will be safely past 12.0 and won't be back-ported, so anything
that works today should work for 12.x releases over the next 3-5 years at
the very least.

I know that these kinds of discussions can be fraught and I'm doing my best
to be honest and open about what's going in, why we want to do thing, and
giving plenty of time for the communities that are using FreeBSD to let us
know of that use in advance of any decisions being made. I'm hoping the
extra data people provide will help us make the initial selection process
be more data driven rather than 'best guess' which turned out to be not
very good.

tl;dr: Not removing anything before 12, devices documented as still working
will remain, there's cheap alternatives for removed drivers, don't panic.


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