From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds) Subject: Re: How do I make swapping work? Date: 31 Jan 1992 17:13:14 GMT
In article <5450@shodha.enet.dec.com> tucker@yuppie.enet.dec.com (David Tucker / KC4ZGO) writes:
>
>I put a 3 at 506 in bootimage, but when I boot, I get a message that says:
>"Unable to get size of swap device".
You have to put a full device number in the word reserved for the
swap-device: the logic is exactly the same as for the root device. Thus
if you want /dev/hd2 to be your swap-device, you'll have to write a 2
(minor nr) into byte 506, and a 3 (= harddisk) into byte 507. You can
use virtually the same program to make a swap-device as you used to
change the boot-device (just change the offset to 2 less).
> Does that mean swapping is not working?
Try to change both the bytes (506 and 507) and things should work.
Other error messages are "unable to find swap signature" and "bad
swap-space bitmap" which both indicate that there is something wrong
with the swap-partition: you probably haven't made it a swap-device with
mkswap. Those messages mean that at least linux finds the device you
indicated: it just cannot make sense of the first page on it which is
used to verify that it really /is/ a swap-device, so that linux won't
overwrite something important.
> How do I know if it is swapping?
You'll notice :). First of all, linux tells you so with "Adding swap:
XXX pages of swap space" at bootup, and if you start running out of real
memory, you'll note that the harddisk starts working overtime, and
things slow down. Generally 2 meg RAM means you swap constantly with
gcc, 4 meg means you'll swap occasionally when trying to optimize big
files (and having other things active, like make), and with 8 M or ram I
haven't swapped yet, but I seldom do heavy computing in more than one
VC.
Linus