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Why *are* the kernels monolithic?
- To: misc_(_at_)_openbsd_(_dot_)_org
- Subject: Why *are* the kernels monolithic?
- From: Chuck Yerkes <chuck+obsd_(_at_)_2004_(_dot_)_snew_(_dot_)_com>
- Date: Tue, 1 Jun 2004 22:08:19 -0400
I ask in seriousness:
Quoting Henning Brauer (lists-openbsd_(_at_)_bsws_(_dot_)_de):
> * Alexander Bochmann <ab_(_at_)_lists_(_dot_)_gxis_(_dot_)_de> [2004-06-01 18:08]:
> > ...on Sun, May 30, 2004 at 07:03:48PM -0400, Chuck Yerkes wrote:
> > > (These kernels keep getting bigger and bigger -- do I *need* to
> > > carry around drivers for 15 SCSI cards and 30ish ethernets on a
> > > box with SISx3 and no SCSI? But openbsd seems module averse.
> > Even if some of the OpenBSD guys don't seem to like
> > it, I regularly strip down my kernels (starting from
> > GENERIC) to exactly the hardware I have in the system.
> > Never tried modules, though.
> > I does make some difference, especially on systems
> > without all the modern stuff like USB:
> > -rw-r--r-- 1 root wheel 2289574 May 11 19:55 /bsd
> > -rw-r--r-- 1 root wheel 5075204 May 3 10:32 /bsd.GENERIC
> > (That's a 3.5 box.)
> and you gained exactly what from that?
> oh right you save 2 picoseconds of boot time (because you boot so
> often) and save 2 megs of RAM... oh yeah
Lesse, box with 16MB of RAM and an 8MB Flash it's booting from.
I figure I just saved 25% of my flash and ~15% of my RAM. Untrivial.
Esp without swap.
But I ask a philosophy question, unless everyones got the blow torches
warmed up and have moved from just propane to adding O2.
The OS is capable of loadable kernel modules. And yet, I'd be
pressed to name any.
While I understand that many of the substructure devices would
want to be in the kernel (mii, etc). But *do* we need live drivers
for 15+ scsi controllers in RAM?
While it's almost moot on a box with 4 or 8GB of RAM, BSD finds itself
often called on in the embedded market. Fitting a computer into small
spaces for low cost (where a second 4MB of RAM *is* a signif cost) is
a great place for BSD. Now these folks aren't using GENERIC anyway,
but not having to work for it is a plus.
Now FreeBSD modularizes EVERY driver and it's a black art to get the
kernel with the right modules ONLY and insane to skip building them
in any fashion.
Is there a place in between?
Does a SPARC 20 NEED to support drivers for xd and xy VME controllers?
I had these disks in 1992. They were old then, but they held 370MB(!)
each with 2 in a 4U rackspace. We moved them from Sun3 to a Sun4 (12MHz
baby!) on a server.
Is there a time, perhaps, to stop adding into a large block of
Or is it just a lack of motivation to break the kernel into "must have
to start" & "and the rest" drivers?
Is it because folks EXPECT that BSD will run on 500MHz+ boxes?
The big rack computers don't care. And I've twiddled kernels long
enough to debug them myself on the < 4 MB boxes. I just wonder
about module phobia or dislike.
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