[TUHS] Code bloat (was: How Unix brings people together, or it's a small...)

Paul Ruizendaal pnr at planet.nl
Wed Feb 8 23:56:21 AEST 2017


If you want to work with LSX, you might have a look at the LSX port I did for the TI990 mini computer: http://1587660.websites.xs4all.nl/cgi-bin/9995/dir?ci=1c38b1fc8792c80b&name=lsx
It is a further development from the work that was done for BKUNIX by Leonid Broukhis (https://sourceforge.net/p/bkunix/code/HEAD/tree/).

You get stuff converted to a dialect of C acceptable by modern compilers, and some kludges like using 'char*' for 'unsigned' and 'int a[2]' for 'long a' are cleaned up.

The repository also has a V6 kernel with similar clean up and some V7 compatibility ('lseek' instead of 'seek', etc.). My next step would be to move to a V7 kernel and add TCP/IP capability. This is how I got interested in the history of sockets and TCP/IP. I have found that the BSD stack (as found in e.g. ULTRIX-11) will not fit in 64KB (note: just the network stack). The BBN stack appears to fit in 56KB, with 15KB of buffers available; I think it could be integrated with a V7 kernel as a second kernel process.


On 8 Feb 2017, at 12:21 , Nick Downing wrote:

> Yes, NetBSD and 386BSD are interesting. They could well form a good
> basis for a minimal but fully functional OS for a modern platform. One
> reservation I have though, is as follows: When 386BSD and its
> derivatives like OpenBSD, NetBSD, FreeBSD came out, Unix was still
> encumbered and thus they had to be based on 4.4BSD Lite (not even
> NET/2 was safe). Nobody made an unencumbered version of say 4.3BSD or
> even NET/2, even though it was theoretically possible, by examining
> what had to be taken out/added to produce 4.4BSD Lite.
> Given that Unix is now unencumbered I believe there is no point
> adopting 4.4, or even 4.3Reno, because the main thing done in those
> releases as far as I know, is to add partial POSIX compliance. But if
> you want POSIX compliance you will not achieve minimality. As an
> example consider the BSD sigvec() routine. POSIX calls this
> sigaction(), the old SV_ONSTACK flag becomes SA_ONSTACK, the old
> integer mask becomes a sigset_t and so on... and in any reasonable
> POSIX compliant BSD the two calls are gonna have to coexist, etc.
> As to 32V, I appreciate your idea, as I was having some similar
> thoughts myself. However I personally wouldn't use 32V as a basis for
> any serious porting work, because I would assume V7 and 4.3 are much
> more stable and well tested, since they ran in a lot of installations
> over a long time. That's not to denigrate the huge achievement in
> porting V7 to the VAX and producing 32V, but it probably has some
> rough edges that were smoothed out over time to produce the 4BSDs. The
> situation is a bit different for kernel/toolchain/other userspace.
> As to the kernel I have been trying to make a detailed comparison
> between 32V and the BSDs, but have been a bit put off by the fact that
> all files moved around and may have been renamed, I will figure it all
> out eventually though. As to the toolchain I have compared it quite
> carefully with 4.3BSD, and I conclude you should use the later
> toolchain as there is no disadvantage and some advantages to doing so.
> As to the rest of the userspace, I BELIEVE that it's stock V7 with any
> 32-bit issues fixed, but I suspect somewhat hastily and superficially.
> Producing a 32V-like kernel from 4.3BSD sources would probably be
> quite difficult, it would be relatively easy to disable added system
> calls, but harder to disable things like setpgrp() or the associated
> support in the TTY drivers. More seriously the memory management would
> have to change, I am planning however to make virtual memory optional
> in the 4.3BSD kernel, by maybe putting the 32V code back in, protected
> by #ifndef VM or some such (somewhat like Steven Schultz has done in
> porting 4.3BSD to PDP-11 to produce 2.11BSD).
> On the other hand producing a 32V-like userland from the 4.3BSD
> sources would be pretty easy, I think just delete the sources for any
> executables that weren't distributed with 32V and possibly, if any of
> the tools seem particularly bloated, comment out any command line
> switches or features that weren't in 32V. Going to this level of
> effort would likely be pointless though. Another option would be
> taking V7 and re-porting it (except the toolchain) over to a 32-bit
> environment and kernel. I have developed over the past months, tools
> that make this relatively straightforward, and in the process would
> rediscover any 32-bit issues that were fixed in creating 32V. So I
> wouldn't use 32V.
> On a slightly different tack, I also have been for some time
> investigating the idea of an Apple II port of Unix, there are massive
> technical issues to be solved, but I think I got a bit closer the
> other night when I decided to collect all information and resources I
> could find about Mini-Unix and LSX (LSI Unix). Both are
> self-supporting V6-based environments, the compiler can only compile
> small programs but it is nonetheless possible for each Unix to
> recomple itself. LSX I believe could run from floppies (dunno about
> 140K floppies) in less than 64K.
> So, you know, true minimality is a relative term. We want something
> LSX-like for an Apple II, something 2.11BSD-like for an IBM PC/XT or
> 286 (as Peter Jeremy noted, it's a good fit, and I'd be interested to
> know more), something 4.3BSD-like for a VAX or 386... something a bit
> more fully featured for a modern 64-bit multi-gigabyte system... but
> just not as bloated as what we currently rely on. Hmm well it's hard.
> What I do know, is that I have a lot of old hardware with <16M RAM and
> Linux won't run on it anymore, and this annoys me very greatly.
> In talking about FreeBSD/Linux bloat I forgot to mention the packet
> filter, iptables (Linux) or pf (FreeBSD). I have a bit of experience
> with this, since I regularly used to put 2 Ethernet cards in my home
> server and make it Internet facing through one of them and share the
> connection using NAT through the other card. But I've come to the
> conclusion this is stupid, and moreover, that putting a complete
> mini-language into the kernel just for this purpose is utterly stupid.
> Programming the thing from userspace is incredibly intricate, and all
> this complexity serves no purpose.
> I recently found out about SLIRP (userspace packet rewriting) and I
> think this would be a good way to implement NAT on servers or routers
> that actually need to do NAT -- just make a userspace process that
> runs something SLIRP-like and has a raw socket to the second Ethernet
> card, and Bob's your uncle.
> But this got me thinking along pretty productive lines in terms of the
> tiny Apple II port -- I have been wanting to put the 2.11BSD network
> stack into an Apple II for a long time, but I've now realized this is
> not necessary. A much better approach for those Mini-Unix or LSX or
> even V7 systems, would be to have a userspace library that does SLIP
> and contains its own TCP, UDP, IP drivers, resolver and so on. Then if
> you run a userspace program like say, ftp, which is linked to the
> userspace TCP library, it would basically just open /dev/ttyXX, bring
> up the SLIP link itself, do any necessary downloads etc, then close
> the TTY and stop responding to any IP stuff coming over the SLIP link
> whilst you quit to the prompt, until another program reopens it.
> cheers, Nick
> On Wed, Feb 8, 2017 at 2:56 PM, Jason Stevens
> <jsteve at superglobalmegacorp.com> wrote:
>> What about NetBSD 1.1 or even 386BSD?
>> There never was a 4.2 or 4.3 for i386 was there?
>> I'd guess the 32v userland could be built on early 4.4BSD Lite/NET2 greatly
>> reducing its footprint.
>> On February 8, 2017 11:47:03 AM GMT+08:00, Nick Downing
>> <downing.nick at gmail.com> wrote:
>>> This is an issue that interests me quite a bit, since I was running
>>> FreeBSD in an effort to get around Linux bloat problems discussed.
>>> Well not that I really mind Linux as a user interface / runtime
>>> environment / main development machine, but I think it probably
>>> shouldn't be used as a "least common denominator" for development
>>> since you end up introducing unwanted dependencies on a whole lot of
>>> stuff.
>>> So I was running FreeBSD as a more minimal *nix. I did quite a lot of
>>> interesting stuff with FreeBSD such as setting up diskless
>>> workstations in my home, etc. I spent a lot of time tinkering around
>>> in the kernel code. I was planning to do some serious development on
>>> 4.4BSDLite or FreeBSD to create an operating system more to my liking.
>>> So, I was looking carefully at differences since ancient *nixes.
>>> And, I can say that FreeBSD is pretty bloated. Umm well they've added
>>> SMP, at the time it was using the Giant Lock although that could be
>>> fixed by now. They've added VFS and NFS of course. They've added an
>>> entire subsystem for block devices IIRC that handles partitioning and
>>> possibly some other sophisticated stuff, which I believe is their own
>>> design. Umm the kqueues and I believe they have their own
>>> implementation of kernel threading or lightweight processes including
>>> some sort of idle daemon. The network stack is heavily upgraded, to
>>> the extent I looked into it, the added features are things you would
>>> want (syncookies = DOS protection, etc) but also could not possibly be
>>> called minimal, and would preclude running it on other than a
>>> multi-megabyte machine. They have multiple ABIs so the kernel can
>>> accept Linux or BSD syscalls or whatever else (I used it to run
>>> Acrobat Reader Linux on my FreeBSD desktop). Umm I am pretty sure they
>>> have kernel modules ala Linux. Lots and lots and lots of stuff... and
>>> that's only considering the kernel. If you look in the ports
>>> collection you see they have incredible amounts of bloat there too...
>>> for instance GNOME, Libreoffice, LATEX, gcc, python... not that I'm
>>> denigrating these tools, since they do invaluable work and I use them
>>> every day, but the point is, you CANNOT call them minimal.
>>> The quest for a clean minimal system goes on ->. FreeBSD is not the
>>> answer. In fact I believe 4.3BSD-Reno and 4.4 go strongly offtrack.
>>> cheers, Nick
>>> On Wed, Feb 8, 2017 at 1:55 PM, Greg 'groggy' Lehey <grog at lemis.com>
>>> wrote:
>>>> On Tuesday,  7 February 2017 at 15:38:40 -0800, Steve Johnson wrote:
>>>>> Looking back, the social dynamics of the Unix group helped a lot in
>>>>> keeping the bloat small.   The rule was, whoever touches something
>>>>> last becomes its owner.  Of course, we were all free to complain
>>>>> about things, and did, but the amalgamation of tinkerings that
>>>>> characterizes most of the Linux commands just didn't happen.
>>>> Out of interest: where do you (or others) consider that the current
>>>> BSD projects it in this comparison?
>>>> Greg
>>>> --
>>>> Sent from my desktop computer.
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>> --
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