Subject: Re: Swap beginning with cylinder 0
To: None <mouse@Collatz.McRCIM.McGill.EDU>
From: David S. Miller <>
List: tech-kern
Date: 05/22/1996 23:12:28
   Date: Wed, 22 May 1996 20:48:35 -0400
   From: der Mouse <mouse@Collatz.McRCIM.McGill.EDU>

   After exchanging some email with Theo (Theo! gasp! :-) on the subject
   of this can of worms about reserving part of a swap area to avoid
   swapping over disk labels and the like, the alternative that seems best
   to me is to define a new ioctl for disk drivers.  If we call this
   ioctl, for the sake of argument, DIOCSWAPSKIP, then the idea is that
   the swap code does a DIOCSWAPSKIP on the swap device to find out how
   much it should skip.

What SunOS does is when it is told to start swapping on a partition,
it checks out what the absolute "entire disk" starting block is for
the slice, and if it is zero or less than the space occupied by a
disklabel etc. then it adjusts the base block to the "safe" starting

David S. Miller