From owner-freebsd-stable@FreeBSD.ORG  Wed Aug 10 08:21:39 2011
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Cc: freebsd-stable@freebsd.org, daniel@digsys.bg
Subject: Re: 32GB limit per swap device?
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Chuck Swiger <cswiger@mac.com> wrote:

> On Aug 9, 2011, at 7:26 AM, Daniel Kalchev wrote:
> > I am trying to set up 64GB partitions for swap for a system that
> > has 64GB of RAM (with the idea to dump kernel core etc). But, on
> > 8-stable as of today I get:
> > 
> > WARNING: reducing size to maximum of 67108864 blocks per swap unit
> > 
> > Is there workaround for this limitation?
>
> Apparently, the 32GB swapspace limit is per swap area; you can add
> up to 4 swap areas so create two or three 32GB swap partitions.

Will that enable a 64GB dump?  In 8.1, dumpon(8) says:

     The dumpon utility is used to specify a device where the kernel
     can save a crash dump in the case of a panic.
     ...
     For most systems the size of the specified dump device must be
     at least the size of physical memory.
     ...
     The dumpon utility will refuse to enable a dump device which is
     smaller than the total amount of physical memory as reported by
     the hw.physmem sysctl(8) variable.

Note the use of the singluar:  "a device" and "the specified device".