Subject: Re: kern/22774: there is no way to swapctl -a to a wrongly typed partition
To: None <tv@pobox.com>
From: Simon Burge <simonb@wasabisystems.com>
List: netbsd-bugs
Date: 09/15/2003 01:03:13
tv@pobox.com wrote:
> >Number: 22774
> >Category: kern
> >Synopsis: there is no way to swapctl -a to a wrongly typed partition
> [ ... ] Problem is, the faked disklabel cannot be written to the disk,
> since swap does not typically leave the disklabel space alone at the start
> of the disk (unlike ffs).
This isn't true. See the comments in uvm_swap.c:
* for block special files, we want to make sure that leave
* the disklabel and bootblocks alone, so we arrange to skip
* over them (arbitrarily choosing to skip PAGE_SIZE bytes).
* note that because of this the "size" can be less than the
* actual number of blocks on the device.
The raid1 set that I swap on is set up so that the swap partition
starts at the start of the "disk":
4 partitions:
# size offset fstype [fsize bsize cpg/sgs]
b: 4194176 0 swap # (Cyl. 0 - 4095*)
c: 4194176 0 4.2BSD 0 0 0 # (Cyl. 0 - 4095*)
d: 4194176 0 4.2BSD 0 0 0 # (Cyl. 0 - 4095*)
Simon.
--
Simon Burge <simonb@wasabisystems.com>
NetBSD Support and Service: http://www.wasabisystems.com/