Hello,
I have a DellPoweredge 2400, with two processors, but for some reason only one is visible atleast to freebsd[ i know this because top shows shows just one processor], Linux also detects just one processor, i have recompiled the kernel to include SMP support;

options SMP # Symmetric MultiProcessor Kernel
options APIC_IO # Symmetric (APIC)

what could be causing this?
NB-> bellow is a copy of demesg.today

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Copyright (c) 1992-2004 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
The Regents of the University of California. All rights reserved.
FreeBSD 4.10-RELEASE #1: Thu Jan 13 17:31:52 EAT 2005
makko@nms.ispkenya.com:/usr/src/sys/compile/BUGS
Timecounter "i8254" frequency 1193182 Hz
CPU: Intel Pentium III (598.11-MHz 686-class CPU)
Origin = "GenuineIntel" Id = 0x681 Stepping = 1

Features=0x383fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,MMX,FX
SR,SSE>
real memory = 536862720 (524280K bytes)
avail memory = 517005312 (504888K bytes)
Changing APIC ID for IO APIC #0 from 0 to 2 on chip
Changing APIC ID for IO APIC #1 from 0 to 3 on chip
Programming 16 pins in IOAPIC #0
IOAPIC #0 intpin 2 -> irq 0
Programming 16 pins in IOAPIC #1
FreeBSD/SMP: Multiprocessor motherboard: 2 CPUs
cpu0 (BSP): apic id: 1, version: 0x00040011, at 0xfee00000
cpu1 (AP): apic id: 0, version: 0x00040011, at 0xfee00000
io0 (APIC): apic id: 2, version: 0x000f0011, at 0xfec00000
io1 (APIC): apic id: 3, version: 0x000f0011, at 0xfec01000
Preloaded elf kernel "kernel" at 0xc0537000.
Pentium Pro MTRR support enabled
md0: Malloc disk
Using $PIR table, 11 entries at 0xc00fc320
npx0: <math processor> on motherboard
npx0: INT 16 interface
pcib0: <ServerWorks NB6635 3.0LE host to PCI bridge> on motherboard
IOAPIC #1 intpin 0 -> irq 2
pci0: <PCI bus> on pcib0
pcib1: <PCI to PCI bridge (vendor=8086 device=0962)> at device 2.0 on pci0
IOAPIC #1 intpin 15 -> irq 5
IOAPIC #1 intpin 14 -> irq 10

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

regards
Timothy.

I see two processors there.

cpu0 (BSP): apic id: 1, version: 0x00040011, at 0xfee00000
cpu1 (AP): apic id: 0, version: 0x00040011, at 0xfee00000

Are you sure it isn't seeing both?

Start a buildworld (no options) and then open a new window and run "top" in it. What is your idle.

SMP: AP CPU #1 Launched!
pass2 at ahc0 bus 0 target 6 lun 0
pass2: <DELL 1x6 U2W SCSI BP 5.35> Fixed Processor SCSI-2 device
pass2: 3.300MB/s transfers
da0 at ahc0 bus 0 target 4 lun 0
da0: <MAXTOR ATLASU320_36_SCA B120> Fixed Direct Access SCSI-3 device
da0: 80.000MB/s transfers (40.000MHz, offset 127, 16bit), Tagged Queueing Enabled
da0: 34732MB (71132959 512 byte sectors: 255H 63S/T 4427C)
da1 at ahc0 bus 0 target 5 lun 0
da1: <MAXTOR ATLASU320_36_SCA B120> Fixed Direct Access SCSI-3 device
da1: 80.000MB/s transfers (40.000MHz, offset 127, 16bit), Tagged Queueing Enabled
da1: 34732MB (71132959 512 byte sectors: 255H 63S/T 4427C)

shouldnt it show "SMP: AP CPU #2 Launched!" after this?

use dmesg | grep -i cpu

you can use top for cpu's use.

cpu0 (BSP): apic id: 1, version: 0x00040011, at 0xfee00000
cpu1 (AP): apic id: 0, version: 0x00040011, at 0xfee00000

No, I don't see why it would. Your CPU #0 is already running at boot. At that point in the boot process it appears to just be saying the second CPU is now ready for use by the system.

The quickest way to tell is to do something which will bog down one of the processors... then use top to show the idle is [about] 50% well... it will be lower then 50% but it won't be near 0% like if you only had one processor.

Note: with no options this will only use one processor and I am sure of that... (unless you have a custom make.conf where you specify the J option).

Then run top and see how idle your system is.

You can then (after you are sure) just ^C the build and "make clean"

This is from another persons dmesg not my own. It is a perfectly working quad-cpu system. You'll note that only the AP processors need to be launched. the BSP is already running... what do you think is processing the kernel and printing the messages before the AP cpu's are launched?

Edit: Note: BSP -- Boot Strap Processor
AP -- Application Processor (namely any processor that is not the BSP)