svn commit: r304187 - in head: . share/man/man4 sys/conf sys/dev/mcd sys/modules sys/modules/mcd

[Konstantin Belousov]

On Thu, Aug 18, 2016 at 09:28:57PM -0600, Warner Losh wrote:
> On Thu, Aug 18, 2016 at 12:50 AM, Julian Elischer <julian at freebsd.org> wrote:
> > On 16/08/2016 4:54 AM, John Baldwin wrote:
> >>
> >> On Monday, August 15, 2016 08:38:02 PM John Baldwin wrote:
> >>>
> >>> Author: jhb
> >>> Date: Mon Aug 15 20:38:02 2016
> >>> New Revision: 304187
> >>> URL: https://svnweb.freebsd.org/changeset/base/304187
> >>>
> >>> Log:
> >>>    Remove the mcd(4) driver for Mitsumi CD-ROM players.
> >>>       This is a driver for a pre-ATAPI ISA CD-ROM adapter.  As noted in
> >>>    the manpage, this driver is only useful as a backend to cdcontrol to
> >>>    play audio CDs since it doesn't use DMA, so its data performance is
> >>>    "abysmal" (and that was true in the mid 90's).
> >>
> >> No one stepped up to test patches for it either when I last posted patches
> >> to
> >> convert it from timeout(9) to callout(9).  I have a few more drivers that
> >> are
> >> both very old and that people have no business using in 12 (think ISA
> >> adapters that don't do DMA and can't be used with pccard) that I will be
> >> removing over the next little while.  I brought up a list of drivers on
> >> arch@
> >> a couple of years ago and the conversation drifted off into the weeds
> >> about
> >> trimming GENERIC, etc.  No one objected to the specific drivers I listed
> >> though (and I got a few pleas of "please remove").  If someone shows up
> >> desperately clutching an ISA adapter they can always dig up the source
> >> from
> >> svn and deal with forward porting it for whatever API changes have
> >> happened
> >> since it was removed.
> >
> >
> > I would imagine any machine still holding one of these probably has not
> > enough memory to run FreeBSD.
> >
> > would we still run in 2MB?
> 
> With insane levels of tuning, we can run in 32MB userland that can do
> things. Even 64MB is tight w/o some tuning. 16MB is almost certainly
> right out except for very specialized situations. 2MB? We can't even
> load the loader in that :(. Oh, and all these memory configs are only
> possible if you tweak the loader's block cache...
> 

32MB is quite usable.  Without any tuning, you get slightly less than 10MB
for userspace, which is enough to for many things, and plenty if swap is
added.

Note that you cannot boot on such configurations since loader was broken,
but if you do manage to jump to kernel, things were fine several months
ago.  I tested my relatively recent OOM changes on 32MB qemu config.
> Warner