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* [TUHS] 2.9BSD on an actual rl02 - swap confusion
@ 2015-02-08 20:42 Noel Chiappa
  2015-02-08 20:52 ` Jacob Ritorto
  2015-02-08 22:03 ` Clem Cole
  0 siblings, 2 replies; 7+ messages in thread
From: Noel Chiappa @ 2015-02-08 20:42 UTC (permalink / raw)


    > From: Jacob Ritorto

    > I'm having trouble understanding how to get my swap configured. Since
    > rl02s are so little, the MAKE file in /dev doesn't partition them into
    > a, b, c, etc. However, when MAKE makes the /dev/rl0 device, it uses
    > only 8500 of its 10000 blocks, so what would presumably be intended as
    > swap space does exist. Swap is usually linked to the b partition,
    > right? So how do I create this b partition on an rl02?

I don't know how the later systems work, but in V6, the swap device, and the
start block / # of blocks are specified in the c.c configuration file (i.e.
they are compiled into the system). So you can take one partition, and by
specifying less than the full size to 'mkfs', you can use the end of the
partition for swap space (which is presumably what's happening with /dev/rl0
here).

	Noel



^ permalink raw reply	[flat|nested] 7+ messages in thread
* [TUHS] 2.9BSD on an actual rl02 - swap confusion
@ 2015-02-08 22:42 Noel Chiappa
  2015-02-08 23:45 ` Clem Cole
  0 siblings, 1 reply; 7+ messages in thread
From: Noel Chiappa @ 2015-02-08 22:42 UTC (permalink / raw)


    > From: Clem Cole <clemc at ccc.com>

    > Once people started to partition them, then all sort of new things
    > occurred and I that's when the idea of a dedicated swap partition came
    > up. I've forgotten if that was a BSDism or UNIX/TS.

Well, vanilla V6 had i) partitioned drives (that was the only way to support
an RP03), and ii) the swap device in the c.c config file. That's all you need
to put swap in its own partition. (One of the other MIT-LCS groups with V6
did that; we didn't, because it was better to swap off the RK, which did
multi-block transfers in a single I/O operation.)

    > As I recall in V6 and I think V7, the process was first placed in the
    > swap image before the exec (or at least space reserved for it).

As best I understand it, the way fork worked in V6 was that if there was not
enough memory for an in-core fork (in which case the entire memory of the
process was just copied), the process was 'swapped out', and the swapped out
image assumed the identity of the child.

But this is kind of confusing, because when I was bringing up V6 under the
Ersatz11 simulator, I had a problem where the swapper (process 0) was trying
to fork (with the child becoming 1 and running /etc/init), and it did the
'swap out' thing. But there was a ton of free memory at that point, so... why
was it doing a swap? Eh, something to investigate sometime...

	Noel



^ permalink raw reply	[flat|nested] 7+ messages in thread
* [TUHS] 2.9BSD on an actual rl02 - swap confusion
@ 2015-02-08 19:28 Jacob Ritorto
  0 siblings, 0 replies; 7+ messages in thread
From: Jacob Ritorto @ 2015-02-08 19:28 UTC (permalink / raw)


Hi,
  I'm having trouble understanding how to get my swap configured.  Since
rl02s are so little, the MAKE file in /dev doesn't partition them into a,
b, c, etc.  However, when MAKE makes the /dev/rl0 device, it uses only 8500
of its 10000 blocks, so what would presumably be intended as swap space
does exist.  Swap is usually linked to the b partition, right?  So how do I
create this b partition on an rl02?  Or am I getting this horribly wrong?

thx
jake
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^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2015-02-08 23:45 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-02-08 20:42 [TUHS] 2.9BSD on an actual rl02 - swap confusion Noel Chiappa
2015-02-08 20:52 ` Jacob Ritorto
2015-02-08 22:03 ` Clem Cole
2015-02-08 22:09   ` Ronald Natalie
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2015-02-08 22:42 Noel Chiappa
2015-02-08 23:45 ` Clem Cole
2015-02-08 19:28 Jacob Ritorto

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