additional note:
/etc/make.conf contains the line "CPUTYPE=pentium4",
no other gcc options

[root@paprika] /usr/obj/usr/src/sys/UP# cat /usr/src/sys/i386/conf/UP                                              [104]
cpu             I686_CPU
ident           GENERICUP

makeoptions     DEBUG=-g                # Build kernel with gdb(1) debug symbols

options INVARIANTS
options INVARIANT_SUPPORT
options WITNESS

options         SCHED_ULE               # ULE scheduler
options         PREEMPTION              # Enable kernel thread preemption
options         INET                    # InterNETworking
options         INET6                   # IPv6 communications protocols
options         FFS                     # Berkeley Fast Filesystem
options         SOFTUPDATES             # Enable FFS soft updates support
options         UFS_ACL                 # Support for access control lists
options         UFS_DIRHASH             # Improve performance on big directories
options         UFS_GJOURNAL            # Enable gjournal-based UFS journaling
options         MD_ROOT                 # MD is a potential root device
options         NFSCLIENT               # Network Filesystem Client
options         NFSSERVER               # Network Filesystem Server
options         NFSLOCKD                # Network Lock Manager
options         NFS_ROOT                # NFS usable as /, requires NFSCLIENT
options         MSDOSFS                 # MSDOS Filesystem
options         CD9660                  # ISO 9660 Filesystem
options         PROCFS                  # Process filesystem (requires PSEUDOFS)
options         PSEUDOFS                # Pseudo-filesystem framework
options         GEOM_PART_GPT           # GUID Partition Tables.
options         GEOM_LABEL              # Provides labelization
options         COMPAT_43TTY            # BSD 4.3 TTY compat [KEEP THIS!]
options         COMPAT_FREEBSD4         # Compatible with FreeBSD4
options         COMPAT_FREEBSD5         # Compatible with FreeBSD5
options         COMPAT_FREEBSD6         # Compatible with FreeBSD6
options         SCSI_DELAY=5000         # Delay (in ms) before probing SCSI
options         KTRACE                  # ktrace(1) support
options         STACK                   # stack(9) support
options         SYSVSHM                 # SYSV-style shared memory
options         SYSVMSG                 # SYSV-style message queues
options         SYSVSEM                 # SYSV-style semaphores
options         _KPOSIX_PRIORITY_SCHEDULING # POSIX P1003_1B real-time extensions
options         KBD_INSTALL_CDEV        # install a CDEV entry in /dev
options         ADAPTIVE_GIANT          # Giant mutex is adaptive.
options         STOP_NMI                # Stop CPUS using NMI instead of IPI
options         AUDIT                   # Security event auditing

# CPU frequency control
device          cpufreq

# Bus support.
device          eisa
device          pci

# Floppy drives
device          fdc

# ATA and ATAPI devices
device          ata
device          atadisk         # ATA disk drives
device          ataraid         # ATA RAID drives
device          atapicd         # ATAPI CDROM drives
device          atapifd         # ATAPI floppy drives
device          atapist         # ATAPI tape drives
options         ATA_STATIC_ID   # Static device numbering

# SCSI peripherals
device          scbus           # SCSI bus (required for SCSI)
device          ch              # SCSI media changers
device          da              # Direct Access (disks)
device          sa              # Sequential Access (tape etc)
device          cd              # CD
device          pass            # Passthrough device (direct SCSI access)
device          ses             # SCSI Environmental Services (and SAF-TE)

# RAID controllers
device          twe             # 3ware ATA RAID

# atkbdc0 controls both the keyboard and the PS/2 mouse
device          atkbdc          # AT keyboard controller
device          atkbd           # AT keyboard
device          psm             # PS/2 mouse

device          kbdmux          # keyboard multiplexer

device          vga             # VGA video card driver

device          splash          # Splash screen and screen saver support

# syscons is the default console driver, resembling an SCO console
device          sc

device          agp             # support several AGP chipsets

# Add suspend/resume support for the i8254.
device          pmtimer

# Serial (COM) ports
device          sio             # 8250, 16[45]50 based serial ports
device          uart            # Generic UART driver

# PCI Ethernet NICs.
device          em              # Intel PRO/1000 Gigabit Ethernet Family

# PCI Ethernet NICs that use the common MII bus controller code.
# NOTE: Be sure to keep the 'device miibus' line in order to use these NICs!
device          miibus          # MII bus support
device          fxp             # Intel EtherExpress PRO/100B (82557, 82558)

# Pseudo devices.
device          loop            # Network loopback
device          random          # Entropy device
device          ether           # Ethernet support
device          sl              # Kernel SLIP
device          ppp             # Kernel PPP
device          tun             # Packet tunnel.
device          pty             # Pseudo-ttys (telnet etc)
device          md              # Memory "disks"
device          gif             # IPv6 and IPv4 tunneling
device          faith           # IPv6-to-IPv4 relaying (translation)
device          firmware        # firmware assist module

# The `bpf' device enables the Berkeley Packet Filter.
# Be aware of the administrative consequences of enabling this!
# Note that 'bpf' is required for DHCP.
device          bpf             # Berkeley packet filter

# USB support
device          uhci            # UHCI PCI->USB interface
device          ohci            # OHCI PCI->USB interface
device          ehci            # EHCI PCI->USB interface (USB 2.0)
device          usb             # USB Bus (required)
#device         udbp            # USB Double Bulk Pipe devices
device          ugen            # Generic
device          uhid            # "Human Interface Devices"
device          ukbd            # Keyboard
device          ulpt            # Printer
device          umass           # Disks/Mass storage - Requires scbus and da
device          ums             # Mouse