8 Feb
2015
8 Feb
'15
8:42 p.m.
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
8 Feb
8 Feb
8:52 p.m.
New subject: 2.9BSD on an actual rl02 - swap confusion
Hey, thanks Guys! Ok, good that the kernel already knows about it.
The actual problem I'm having is that ps doesn't work.
I assume it tries to look at /dev/swap as its pointer, but since there's
no /dev/rl0a, dev/swap has nothing reasonable to point to, so ps fails with
/dev/swap: no such device (iirc).
Was thinking of experimentally linking /dev/swap to rl0 but logic
dictates that would trash the root filesystem (which is nbd since I can
easily restore the 2.9 rl02 root from the archives with Warren's vtserver!)
Gonna go read some source. Thanks!
jake
On Sun, Feb 8, 2015 at 3:42 PM, Noel Chiappa <jnc(a)mercury.lcs.mit.edu>
wrote:
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
_______________________________________________
TUHS mailing list
TUHS(a)minnie.tuhs.org
https://minnie.tuhs.org/mailman/listinfo/tuhs
10:03 p.m.
New subject: 2.9BSD on an actual rl02 - swap confusion
On Sun, Feb 8, 2015 at 3:42 PM, Noel Chiappa <jnc(a)mercury.lcs.mit.edu>
wrote:
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).
Ah Noel - Thanks for the refresher course. That's right. I now remember
it. I knew it was compiled into the kernel but I had forgotten the details.
It was not until much later that the swap image became less screwed
down/more reflexible. You first needed to get to larger disks (rp05/rp06)
which had to be partitioned because they overflowed a 16 bit integer.
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. Certainly by the time of Sam's
4.1A?? configuration tool that created conf.c and low.s it had already been
in for a while.
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). So you had to
have a swap space to boot because to fork the "init" it needed to assigned
to the swap space (chick/egg issue). When demand support was added to the
kernel, the process did not have to have that requirement, so it meant swap
set up could be a post initial program load operation for the start
sequence.
Clem
Clem
10:09 p.m.
New subject: 2.9BSD on an actual rl02 - swap confusion
Yep, certain of the smaller drives like RK05’s had no way of “partitioning them.” So you
needed the swapstart to put it at the end of the volume.
Even before we got large drives, we put our swap on it’s own fixed head disk (RS-11).
Actually, in retrospect it probably would have been better to put temp there rather than
swap, but it seemed to be a good idea at the time. Later we got the bulk core boxes
that emulated the fixed head disks and did put temp there.
3372
days inactive
3372
days old
3 comments
4 participants
participants (4)
-
Clem Cole -
Jacob Ritorto -
jnc＠mercury.lcs.mit.edu -
Ronald Natalie