Subject: NetBSD/alpha kernel configuration
To: None <>
From: Erik E. Fair <>
List: port-alpha
Date: 04/22/1999 02:41:48
I've been playing with custom kernels this evening (it's nice to be able to
build a kernel in 15 min!). The first thing I noticed is that the GENERIC
kernel is missing some moderately commonly used options:

NETATALK (well, we could argue about this one)

It's also my intention to try out the RAIDframe stuff, so I turned that on,
too. Why doesn't the GENERIC kernel have the kitchen sink in it? There also
seem to be some Alpha (or DEC) specific options not documented in
options(4), e.g. TCVERBOSE.

Secondly, in NetBSD/sparc, we achieved something that Sun never did: a
GENERIC that boots on three of the four 32-bit system architectures: sun4,
sun4c, and sun4m (there is a sun4u, but there's no support for those
systems yet, and they are few in number because they were very expensive).
However, that generality comes at a cost: indirection through function
pointers for every MMU operation. So, compiling up a system-specific kernel
wins on performance, quite aside from RAM savings from removing unused
system support and unused drivers.

Naturally, I tried the same thing with NetBSD/alpha; unfortunately, I don't
know the architecture well enough beyond what gets reported in the
autoconfig to know what drivers are required, and which are not, and my
initial attempts to pare down the kernel resulted in kernels that built OK,
but panic'd when I tried to boot them.

Am I wasting my time trying to pare down the kernel (i.e. is the win here
not as big)?


	Erik <>