only 3 of 4GB memory available on amd64 8.1-RC1

Hi all,

I got my hands on a t60 with 4GB of RAM (BIOS displays it)

And I installed 8.1-RC1 on it:

FreeBSD 8.1-RC1 #0: Mon Jun 14 13:40:28 UTC 2010
     root_at_mason.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC amd64
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Intel(R) Core(TM)2 CPU         T5600  _at_ 1.83GHz (1828.76-MHz 
K8-class CPU)
   Origin = "GenuineIntel"  Id = 0x6f6  Family = 6  Model = f  Stepping = 6
 
Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
   Features2=0xe3bd<SSE3,DTES64,MON,DS_CPL,VMX,EST,TM2,SSSE3,CX16,xTPR,PDCM>
   AMD Features=0x20100800<SYSCALL,NX,LM>
   AMD Features2=0x1<LAHF>
   TSC: P-state invariant
real memory  = 4294967296 (4096 MB)
avail memory = 3092344832 (2949 MB)
ACPI APIC Table: <LENOVO TP-79   >
FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
FreeBSD/SMP: 1 package(s) x 2 core(s)
  cpu0 (BSP): APIC ID:  0
  cpu1 (AP): APIC ID:  1



Do I need to configure something special to get the full 4GB of memory?

I only found the PAE hint, but this is for x86 machines, right?

Thanks for any hint.
Andreas