From: geoff@collyer.net
To: 9fans@cse.psu.edu
Subject: Re: [9fans] Acme mailreader
Date: Wed, 15 Dec 2004 16:24:47 -0800 [thread overview]
Message-ID: <8c28239dd33c04e668032c40d598e778@collyer.net> (raw)
In-Reply-To: <B94EBBB8-4EB3-11D9-901F-00112430C042@gmail.com>
OS X is in no sense a micro-kernel. The OS X kernel is huge:
; size /mach_kernel
__TEXT __DATA __OBJC others dec hex
3022848 458752 0 643984 4125584 3ef390
and consists of a heavily-hacked Mach (3, I believe) kernel and a
FreeBSD kernel (with bits from other BSDs), combined into a single
kernel and running in a single address space. The BSD kernel does not
run in user mode. Remember that Mach was, as far as I know, the
largest ``micro-kernel'' ever produced, larger than most or all of its
contemporary ``macro-kernels'', so that some of us called it a
``Machro-kernel''.
I haven't looked very hard (one could check out the mount_* sources
from the Darwin CVS servers), but mount(2) doesn't seem to have much
that's new, except for union mounts, which surprised me. I suspect
that most of the mount_* commands either invoke kernel machinery
(through the ``type'' argument to mount) or pretend to be NFS servers.
I've never yet seen a (l)unix system other than late Research Unix
that made user-mode file servers relatively easy and painless to write
(though I'd love to be shown a counter-example!). Of course, since
many (l)unix systems only allow the super-user to mount anything,
their maintainers may not see much utility in user-mode file servers.
It's sort of a cascade of vision-failures.
Also, /sys/src/cmd/upas/README is a little dated:
--rw-rw-r-- M 5174 sys sys 1041 Dec 11 1999 README
I'm not sure if it pre-dates upas/fs, but it describes how to port the
parts of upas that don't rely on Plan 9 facilities (transport more
than reading). I ported Plan 9's upas back to Unix while at the labs
(and also translated it into limbo), but some parts (e.g., upas/fs)
didn't have an obvious implementation, other than painfully pretending
to be an NFS server, at least at the time.
next prev parent reply other threads:[~2004-12-16 0:24 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-15 15:34 jim
2004-12-15 15:40 ` gdiaz
2004-12-15 15:47 ` jim
2004-12-15 15:50 ` Joseph Stewart
2004-12-15 15:57 ` jim
2004-12-15 16:10 ` Russ Cox
2004-12-15 15:58 ` Charles Forsyth
2004-12-15 16:04 ` jim
2004-12-15 16:24 ` C H Forsyth
2004-12-15 16:31 ` jim
2004-12-15 17:07 ` Russ Cox
2004-12-15 17:30 ` jim
2004-12-15 18:33 ` Russ Cox
2004-12-15 18:49 ` jim
2004-12-15 18:36 ` Axel Belinfante
2004-12-15 18:47 ` jim
2004-12-15 18:51 ` rog
2004-12-15 18:48 ` Skip Tavakkolian
2004-12-15 16:05 ` rog
2004-12-15 16:07 ` rog
2004-12-15 16:09 ` jim
2004-12-16 0:24 ` geoff [this message]
2004-12-16 4:12 ` Ronald G. Minnich
2004-12-16 4:51 ` geoff
2004-12-16 9:25 ` jim
2004-12-16 5:13 ` Skip Tavakkolian
2004-12-16 5:17 ` geoff
2004-12-16 5:20 ` boyd, rounin
2004-12-16 5:34 ` boyd, rounin
2004-12-16 5:29 ` Skip Tavakkolian
2004-12-16 15:54 ` Ronald G. Minnich
2004-12-16 17:52 ` Skip Tavakkolian
2004-12-16 18:13 ` Dave Eckhardt
2004-12-16 5:23 ` Andy Newman
2004-12-16 15:52 ` Ronald G. Minnich
2004-12-16 8:17 ` Martin C.Atkins
2004-12-16 9:35 ` jim
2004-12-16 15:19 ` rog
2004-12-16 15:26 ` jim
2004-12-16 9:30 ` jim
2004-12-16 15:08 ` David Leimbach
2004-12-16 23:22 ` geoff
2004-12-16 23:25 ` boyd, rounin
2004-12-16 23:38 ` Ronald G. Minnich
2004-12-17 1:31 ` Skip Tavakkolian
2004-12-17 15:50 ` Ronald G. Minnich
2004-12-17 4:55 ` [9fans] Acme mailreader - now: User mode filesystems in linux Martin C.Atkins
2004-12-17 9:54 ` Martin C.Atkins
2004-12-17 10:22 ` geoff
2004-12-17 10:45 ` Martin C.Atkins
2004-12-17 11:42 ` Andy Newman
2004-12-17 15:57 ` Ronald G. Minnich
2004-12-17 12:30 ` Latchesar Ionkov
2004-12-17 15:55 ` Ronald G. Minnich
2004-12-17 13:41 ` Derek Fawcus
2004-12-17 14:42 ` Karl Magdsick
2004-12-17 14:56 ` Russ Cox
2004-12-18 0:13 ` Tim Newsham
2004-12-18 0:13 ` boyd, rounin
2004-12-18 3:49 ` Ronald G. Minnich
2004-12-23 16:04 ` boyd, rounin
2004-12-17 15:44 ` Ronald G. Minnich
2004-12-18 12:35 ` Martin C.Atkins
2004-12-17 18:52 ` [9fans] Acme mailreader David Leimbach
2004-12-17 23:20 ` Jack Johnson
2004-12-18 1:00 ` David Leimbach
2004-12-15 16:09 ` Russ Cox
2004-12-15 16:16 ` jim
2004-12-15 16:22 ` boyd, rounin
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