You can use make as much as you like; Go just doesn't need it. You can use
Go to fetch code from internet if you like, or you can do it yourself if
you prefer.
Regarding the "hardwired" directories, you can change it through an
environment variable.
Em 3 de fev de 2018 23:20, "Lyndon Nerenberg" <lyndon(a)orthanc.ca> escreveu:
That's the second endorsement I've seen for Go; I guess I should learn it.
>
In the scheme of "current" languages, Go is pretty good. With two major
caveats, IMO:
1) The build system. It doesn't work with make(1). That makes it a
non-starter for anything other than trivial projects at $WORK. While I
appreciate the arguments for the apparent simplicity of the "go" command,
that doesn't work for us. Which would have been fine, but for the entirely
antagonistic bent they have taken against being able to build Go programs
with make(1). Our build environment entirely precludes Go's promiscuous
insistence on unfettered internet access, and hardwired directory paths.
2) Hardwired directory paths for the development/build environment (see
above).
It seems they have unlearned all the UNIX lessons. Sad, really. I would
love to toss out Python, Ruby, PHP, Perl, et al. And could make the
argument for it, I think. But the build environment will never work in our
shop, therefore Go won't either.
And that ... sucks.
Hi,
Interested in some perspective here since the list has influential Linux
people like Ted Tso.
Linux has been described as influenced by Minix and System V. The Minix
connection is well discussed. The SysV connection something something
Linus had access to a spec manual. But I’d guess reality would be more
gradual — new contributors that liked CSRG BSD would have mostly gravitated
to the continuations in 386/BSDi/Net/Free that were concurrent to early and
formative Linux development.. so there’d be an implicit vacuum of BSD
people for Linux development.
What I am curious about is the continuing ignorance of BSD ideas. Linux
isn’t exactly insular; a lot of critical people and components came much
later on from other SysV flavors (lvm, jfs, xfs, RCU)
The kinds of BSD things I am talking about are ufs, kqueue, jails, pf,
Capsicum. Linux has grown alternatives, but with sometimes willful
ignorance of other technology. It seems clear epoll was not a good design
from the start. Despite jails not being taken to the logical conclusion of
modern containers like zones, the architecture is fundamentally closer
aligned to how people want to securely use containers versus namespaces and
cgroups. And Google ported Capscicum to Linux but it’s basically been
ignored in lieu of nebulous concepts like seccomp. And then there seems to
be outright hostility toward other platforms from the postmodern generation
with things like systemd.
This seems strange to me as BSD people are generally open to other /ideas/,
we have to be careful with Linux code due to license incompatibility, but
the converse is does not seem true either in interest in other ideas or
license hampering code flow.
The history of UNIX is spectacularly successful because different groups
got together at the table and agreeed on the ideas. Is there room for that
in the modern era where Linux is the monopoly OS? The Austin Group is
still a thing but it’s not clear people in any of the Freenix communities
really care about evolving the standards. I get that, but not so much
completely burrying ones head in the sand to what other OSes are doing. Is
there any future for UNIX as an “open system” in this climate or are people
going to go there separate ways?
Regards,
Kevin
We gained John von Neumann on this day in 1903, and if you haven't heard
of him then you are barely human... As computer science goes, he's right
up there with Alan Turing. There is speculation that he knew of Babbage's
work; see
https://cstheory.stackexchange.com/questions/10828/the-relation-between-bab… .
--
Dave Horsfall DTM (VK2KFU) "Those who don't understand security will suffer."
> From: Sergio Pedraja
> I am very interested in your work exactly for the reasons you explain
We will generally be sending messages about it to the CCTalk list (for
collectors of 'classic' computers), so if you want to be notified about it,
sign up there.
We currently have only wire-wrap prototypes (the FPGA is on an off-the-shelf
daughter-card); we're hoping to produce PCB production versions 'soon'. We do
have the technology for getting PCB's, which we have used for doing 'indicator
panels':
http://ana-3.lcs.mit.edu/~jnc/tech/DECIndicatorPanels.html
We have those working (they've been a big help in debugging, actually :-), and
they'll be available too. I don't personally have one of them yet, I'm
_really_ looking forward to watching the lights blink as UNIX boots... :-)
> The only difference is that my PDP-11 is one 23/PLUS. There are some
> differences between this one and the PDP-11/23 and perhaps your emulator
> woudln't work in this PDP-11 model.
No, AFAIK the /23 and /23-PLUS are effectively identical, as far as the QBUS
goes. (Obviously the -PLUS has devices, etc, the plain /23 doesn't, but they
don't enter into whether our board will work with one.)
We also plan at UNIBUS version; the two busses are similar enough that we'll
probably start with a PCB version for that one.
> I will test the working state of my PDP. If all is fine perhaps I could
> help doing with some tests on it.
Sure; use CCTalk.
Noel
As I mentioned recently, Dave Bridgham and I are doing an RK11 emulator (and
soon an RP11, which just will take editing the Verilog a tiny bit) using an
SD card for storage, for heritage computer collectors who want to run their
PDP-11's but don't want to risk a head crash (since replacement heads are now
un-obtainium) - and also for people who have an -11, but no mass storage.
So the last stage was bringing up V6 on a hardware PDP-11/23, using the
emulated RK11, and we were having an issue (which turned out to be partial
block reads/writes not working properly; this has since been fixed, and we
have successfullly booted V6 on the -11/23 with only an SD card).
In the process of debugging that issue, I added logging to the RK driver, and
noticed that in the process of attempting to boot single-user, the system was
trying to do some swapping - two writes, and two reads - before it even tried
doing the fork() to create the shell process, followed by opening /dev/tty8
and doing the exec() of /bin/sh.
This confused me, since both newproc() and expand() have code which uses a
memory-memory copy if there is enough free memory - and on first booting,
there definitely was. Why was it swapping?
So I added some more logging, and the cause turned out that at one point, I
had re-compiled /etc/init - and without thinking about it too hard, had made
it a pure-text program.
And that's what did it: in exec() (called when process 1 tries to exec()
/etc/init), it calls xalloc(), which i) if the text was not already
available, gets together the pure text, and puts a copy on the swap device,
and ii) if the text is not already in core, swaps the rest of the process
out, because, as the code explains:
* if the calling process
* is misplaced in core the text image might not fit.
* Quite possibly the code after "out:" could check to
* see if the text does fit and simply swap it in.
If you're looking at the code, the process doesn't have a data segment at
that point, just the U area; the data will be set up later in the exec()
code, after the call to xalloc() returns, after the process is swapped back
in.
In fact, the process will _never_ have anything other than a U area when in
this code; the only call to xalloc() in the system is immediately preceeded
by an "expand(USIZE)" which throws away everything except the U area.
So I'm contemplating doing what the comment suggests - adding code to check
to see if there's enough memory available to hold the pure text, and if so,
avoiding the swap-out/in of the process' U-only data segment.
If done 'right', it should also be possible to allow avoiding the reading-in
of the text from the swap device, when first exec'ing a pure text...
Probably not as interesting a project as doing the splice() system call was,
but no doubt it will teach me about a corner of the system I don't know very
well (back in the day, doing networking stuff, I was mostly looking at I/O
code).
Although there is potentially a certain amount of amusement in an additional
enhancement, which is trying to make sure there's enough room for both the
text and the data; immediately upon the return from xalloc(), the process is
expanded to have room for the data. Which might involve _another_ swap-out/in
sequence... So perhaps the U area should simply be moved out of the way via a
direct memory-memory copy, rather than swapping it out/in, just before doing
it again!
You are not expected to understand this... :-)
I guess I should first take a look at the PWB1 pure text code, which is
heavily modified from the stock V6, to see what it does - this all may have
already been done there.
Noel
For a while I had been wondering about the origins of a modification to the V6 kernel that places the kernel buffers in a separately mapped area, freeing up space for other things. It is used in some of the early networking code, i.e. both the UoI code and the V6 BBN code (as available on the TUHS Unix Tree).
I came across the following reference in https://www.osti.gov/scitech/servlets/purl/12130675:
“One widely distributed (though undocumented) solution to this hardware limit on the model 40 was a version of Unix by Robert Sidebotham, Faculty of Environmental Design, University of Calgary. His solution was to move the I/O buffers out of kernel space.”
This would explain the modifications being bracketed with "#ifdef UCBUFMOD”.
Some questions for the old hands:
- Was this patch indeed widely known / distributed?
- Widely distributed is not the same as widely used: was it?
Born on this day in 1925, he was a pioneer in human/computer interaction,
and invented the mouse; it wasn't exactly ergonomic, being just a square
box with a button.
--
Dave Horsfall DTM (VK2KFU) "Those who don't understand security will suffer."
So, while bringing up V6 on a hardware PDP-11/23 with an RK11 emulator using
an SD card for storage which Dave Bridgham and I are doing, I found this piece
of code in main() on V6 Unix:
rootdir = iget(rootdev, ROOTINO);
rootdir->i_flag =& ~ILOCK;
u.u_cdir = iget(rootdev, ROOTINO);
u.u_cdir->i_flag =& ~ILOCK;
I don't get why two separate calls to iget(), with the same arguments;
why not replace the second pair of lines with:
u.u_cdir = rootdir;
rootdir->i_count++;
What am I missing?
Noel
>>> LSX has a maximum of three processes that are swapped in and out in a
>>> stack-like fashion. Only one process is ever in core.
>
> I'm having a hard time working out how this works. If process A is swapped
> out, and then B, B has to be swapped in before A can be? But only one process
> is ever in core at a time? To get A in, B has to be moved out? But then B
> would be the last one out, and would have to come in before A?
>
> Anyway, I don't understand why the OS could/would care which order processes
> we swapped in - unless it's something like the 'onion skin' memory allocation
> algorithm of CTSS (which also had only a single process resident at a time,
> IIRC), where, when a small process had to be swapped in, and a large one was
> already in, it only swapped out enough of the large one to make room for the
> small one. The process could recurse, hence the name.
The LSI-11 had 40KB of core. The lower 16KB held the LSX kernel, the upper 24K was
for the active process.
LSX has 3 process slots and 2 swap slots (on floppy!). Optionally, LSX could
be built with an additional background process ("BGOPTION"), but this does
not work very well. Process numbers and swap slots have a 1:1 relationship.
There is a global variable, cpid, with the process number of the current
process, initially zero. Upon boot, LSX will load a shell as process 0.
(There is no swapper process and no init in LSX).
The original LSI-11 kernel code is here:
http://minnie.tuhs.org/cgi-bin/utree.pl?file=LSX/sys
I can refer to source lines in the repository for my TI990 port of it:
https://1587660.websites.xs4all.nl/cgi-bin/9995/artifact/b6ec9496e23efe8c
When a process forks, it writes the current core image out to the
corresponding swap slot (this swaps out the parent) and the core image
is repurposed as the new process (i.e. cpid is incremented and the
proc table filled in):
https://1587660.websites.xs4all.nl/cgi-bin/9995/artifact/3617ec3245c40a69?l…
The child now runs and the parent remains suspended until the child completes.
Yes, this implies no pipes. The shell is modified to emulate pipes with files.
When the child completes, it stores its u area / exit code in its swap slot
(as it is running, the swap slot must be empty. Process 3 has a small swap slot
just for this). Next LSX decreases cpid and the parent process is reloaded from
its swap slot:
https://1587660.websites.xs4all.nl/cgi-bin/9995/artifact/b9c07dfc5add9fc5?l…
The actual swapping happens here:
https://1587660.websites.xs4all.nl/cgi-bin/9995/artifact/b6ec9496e23efe8c?l…
The original PDP11 source has code to compress the empty space between _end and the
stack pointer, which I did not get to work properly.
LSX works well enough to run the standard V6 binaries unmodified. Some need to be
tweaked (e.g. table space in cpp) and the shell needed the pipe change. It can run
the V6 c compiler, but not with a wild card argument: that requires 4 stacked processes
(sh, glob, cc and cpp/c0/..) and LSX allows only 3.
Hope the above makes it a bit more clear.
