FreeBSD Xen PV i386 --> 855MB Max?

[Sean Bruno]

I note that if I scale the i386 PV Xen kernel past 855MB, I get an insta
panic at boot.  I assume that there's a hard limit on the amount of RAMS
we can use here?

Using config file "./ref8-xen32".
Started domain ref8-xen32 (id=133)
WARNING: loader(8) metadata is missing!
GDB: no debug ports present
KDB: debugger backends: ddb
KDB: current backend: ddb
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FreeBSD 8.2-STABLE #1 r224449: Tue Jul 26 09:53:36 PDT 2011

sbruno at ref8-xen32.freebsd.org:/usr/obj/dumpster/scratch/sbruno-scratch/8/sys/XEN i386
WARNING: WITNESS option enabled, expect reduced performance.
panic: pmap_init: page table page is out of range
cpuid = 0
KDB: enter: panic
[thread pid 0 tid 0 ]
Stopped at      0xc010e68a:     movl    $0,0xc03f20b4