xref: /freebsd/sys/i386/conf/NOTES (revision 1f38677ba40b26b861e063e130117143c9342c5d)

#
# NOTES -- Lines that can be cut/pasted into kernel and hints configs.
#
# This file contains machine dependent kernel configuration notes.  For
# machine independent notes, look in /sys/conf/NOTES.  For notes shared
# with amd64, look in /sys/x86/conf/NOTES.
#
#


#####################################################################
# SMP OPTIONS:
#
# The apic device enables the use of the I/O APIC for interrupt delivery.
# The apic device can be used in both UP and SMP kernels, but is required
# for SMP kernels.  Thus, the apic device is not strictly an SMP option,
# but it is a prerequisite for SMP.
#
# Notes:
#
# HTT CPUs should only be used if they are enabled in the BIOS.  For
# the ACPI case, ACPI only correctly tells us about any HTT CPUs if
# they are enabled.  However, most HTT systems do not list HTT CPUs
# in the MP Table if they are enabled, thus we guess at the HTT CPUs
# for the MP Table case.  However, we shouldn't try to guess and use
# these CPUs if HTT is disabled.  Thus, HTT guessing is only enabled
# for the MP Table if the user explicitly asks for it via the
# MPTABLE_FORCE_HTT option.  Do NOT use this option if you have HTT
# disabled in your BIOS.
#
# IPI_PREEMPTION instructs the kernel to preempt threads running on other
# CPUS if needed.  Relies on the PREEMPTION option

# Mandatory:
device		apic			# I/O apic

# Optional:
options 	MPTABLE_FORCE_HTT	# Enable HTT CPUs with the MP Table


#####################################################################
# CPU OPTIONS

#
# You must specify at least one CPU (the one you intend to run on);
# deleting the specification for CPUs you don't need to use may make
# parts of the system run faster.
#
cpu		I486_CPU
cpu		I586_CPU		# aka Pentium(tm)
cpu		I686_CPU		# aka Pentium Pro(tm)

#
# Options for CPU features.
#
# CPU_ATHLON_SSE_HACK tries to enable SSE instructions when the BIOS has
# forgotten to enable them.
#
# CPU_BLUELIGHTNING_3X enables triple-clock mode on IBM Blue Lightning
# CPU if CPU supports it.  The default is double-clock mode on
# BlueLightning CPU box.
#
# CPU_BLUELIGHTNING_FPU_OP_CACHE enables FPU operand cache on IBM
# BlueLightning CPU.  It works only with Cyrix FPU, and this option
# should not be used with Intel FPU.
#
# CPU_BTB_EN enables branch target buffer on Cyrix 5x86 (NOTE 1).
#
# CPU_CYRIX_NO_LOCK enables weak locking for the entire address space
# of Cyrix 6x86 and 6x86MX CPUs by setting the NO_LOCK bit of CCR1.
# Otherwise, the NO_LOCK bit of CCR1 is cleared.  (NOTE 3)
#
# CPU_DIRECT_MAPPED_CACHE sets L1 cache of Cyrix 486DLC CPU in direct
# mapped mode.  Default is 2-way set associative mode.
#
# CPU_DISABLE_5X86_LSSER disables load store serialize (i.e., enables
# reorder).  This option should not be used if you use memory mapped
# I/O device(s).
#
# CPU_ELAN enables support for AMDs ElanSC520 CPU.
#    CPU_ELAN_PPS enables precision timestamp code.
#    CPU_ELAN_XTAL sets the clock crystal frequency in Hz.
#
# CPU_ENABLE_LONGRUN enables support for Transmeta Crusoe LongRun
# technology which allows to restrict power consumption of the CPU by
# using group of hw.crusoe.* sysctls.
#
# CPU_FASTER_5X86_FPU enables faster FPU exception handler.
#
# CPU_GEODE is for the SC1100 Geode embedded processor.  This option
# is necessary because the i8254 timecounter is toast.
#
# CPU_I486_ON_386 enables CPU cache on i486 based CPU upgrade products
# for i386 machines.
#
# CPU_IORT defines I/O clock delay time (NOTE 1).  Default values of
# I/O clock delay time on Cyrix 5x86 and 6x86 are 0 and 7,respectively
# (no clock delay).
#
# CPU_L2_LATENCY specifies the L2 cache latency value.  This option is used
# only when CPU_PPRO2CELERON is defined and Mendocino Celeron is detected.
# The default value is 5.
#
# CPU_LOOP_EN prevents flushing the prefetch buffer if the destination
# of a jump is already present in the prefetch buffer on Cyrix 5x86(NOTE
# 1).
#
# CPU_PPRO2CELERON enables L2 cache of Mendocino Celeron CPUs.  This option
# is useful when you use Socket 8 to Socket 370 converter, because most Pentium
# Pro BIOSs do not enable L2 cache of Mendocino Celeron CPUs.
#
# CPU_RSTK_EN enables return stack on Cyrix 5x86 (NOTE 1).
#
# CPU_SOEKRIS enables support www.soekris.com hardware.
#
# CPU_SUSP_HLT enables suspend on HALT.  If this option is set, CPU
# enters suspend mode following execution of HALT instruction.
#
# CPU_UPGRADE_HW_CACHE eliminates unneeded cache flush instruction(s).
#
# CPU_WT_ALLOC enables write allocation on Cyrix 6x86/6x86MX and AMD
# K5/K6/K6-2 CPUs.
#
# CYRIX_CACHE_WORKS enables CPU cache on Cyrix 486 CPUs with cache
# flush at hold state.
#
# CYRIX_CACHE_REALLY_WORKS enables (1) CPU cache on Cyrix 486 CPUs
# without cache flush at hold state, and (2) write-back CPU cache on
# Cyrix 6x86 whose revision < 2.7 (NOTE 2).
#
# NO_F00F_HACK disables the hack that prevents Pentiums (and ONLY
# Pentiums) from locking up when a LOCK CMPXCHG8B instruction is
# executed.  This option is only needed if I586_CPU is also defined,
# and should be included for any non-Pentium CPU that defines it.
#
# NO_MEMORY_HOLE is an optimisation for systems with AMD K6 processors
# which indicates that the 15-16MB range is *definitely* not being
# occupied by an ISA memory hole.
#
# NOTE 1: The options, CPU_BTB_EN, CPU_LOOP_EN, CPU_IORT,
# CPU_LOOP_EN and CPU_RSTK_EN should not be used because of CPU bugs.
# These options may crash your system.
#
# NOTE 2: If CYRIX_CACHE_REALLY_WORKS is not set, CPU cache is enabled
# in write-through mode when revision < 2.7.  If revision of Cyrix
# 6x86 >= 2.7, CPU cache is always enabled in write-back mode.
#
# NOTE 3: This option may cause failures for software that requires
# locked cycles in order to operate correctly.
#
options 	CPU_ATHLON_SSE_HACK
options 	CPU_BLUELIGHTNING_3X
options 	CPU_BLUELIGHTNING_FPU_OP_CACHE
options 	CPU_BTB_EN
options 	CPU_DIRECT_MAPPED_CACHE
options 	CPU_DISABLE_5X86_LSSER
options 	CPU_ELAN
options 	CPU_ELAN_PPS
options 	CPU_ELAN_XTAL=32768000
options 	CPU_ENABLE_LONGRUN
options 	CPU_FASTER_5X86_FPU
options 	CPU_GEODE
options 	CPU_I486_ON_386
options 	CPU_IORT
options 	CPU_L2_LATENCY=5
options 	CPU_LOOP_EN
options 	CPU_PPRO2CELERON
options 	CPU_RSTK_EN
options 	CPU_SOEKRIS
options 	CPU_SUSP_HLT
options 	CPU_UPGRADE_HW_CACHE
options 	CPU_WT_ALLOC
options 	CYRIX_CACHE_WORKS
options 	CYRIX_CACHE_REALLY_WORKS
#options 	NO_F00F_HACK

# Debug options
options 	NPX_DEBUG	# enable npx debugging

#
# PERFMON causes the driver for Pentium/Pentium Pro performance counters
# to be compiled.  See perfmon(4) for more information.
#
options 	PERFMON

#
# Hints for the non-optional Numeric Processing eXtension driver.
envvar		hint.npx.0.flags="0x0"
envvar		hint.npx.0.irq="13"

#
# `flags' for npx0:
#	0x01	don't use the npx registers to optimize bcopy.
#	0x02	don't use the npx registers to optimize bzero.
#	0x04	don't use the npx registers to optimize copyin or copyout.
# The npx registers are normally used to optimize copying and zeroing when
# all of the following conditions are satisfied:
#	I586_CPU is an option
#	the cpu is an i586 (perhaps not a Pentium)
#	the probe for npx0 succeeds
#	INT 16 exception handling works.
# Then copying and zeroing using the npx registers is normally 30-100% faster.
# The flags can be used to control cases where it doesn't work or is slower.
# Setting them at boot time using hints works right (the optimizations
# are not used until later in the bootstrap when npx0 is attached).
# Flag 0x08 automatically disables the i586 optimized routines.
#


#####################################################################
# HARDWARE DEVICE CONFIGURATION

#
# Optional devices:
#

# 3Dfx Voodoo Graphics, Voodoo II /dev/3dfx CDEV support.  This will create
# the /dev/3dfx0 device to work with glide implementations.  This should get
# linked to /dev/3dfx and /dev/voodoo.  Note that this is not the same as
# the tdfx DRI module from XFree86 and is completely unrelated.
#
# To enable Linuxulator support, one must also load linux.ko and tdfx_linux.ko.

device		tdfx			# Enable 3Dfx Voodoo support

#
# RAID adapters
#
device		pst

#
# Adaptec by PMC RAID controllers, Series 6/7/8 and upcoming families
device		aacraid		# Container interface, CAM required

#
# Network interfaces:
#

# sbni: Granch SBNI12-xx ISA and PCI adapters
# vmx:	VMware VMXNET3 Ethernet (BSD open source)
# wpi:	Intel 3945ABG Wireless LAN controller
#	Requires the wpi firmware module

# Order for ISA/EISA devices is important here

envvar		hint.cs.0.at="isa"
envvar		hint.cs.0.port="0x300"
envvar		hint.ed.0.at="isa"
envvar		hint.ed.0.port="0x280"
envvar		hint.ed.0.irq="5"
envvar		hint.ed.0.maddr="0xd8000"
# Hint for the i386-only ISA front-end of le(4).
envvar		hint.le.0.at="isa"
envvar		hint.le.0.port="0x280"
envvar		hint.le.0.irq="10"
envvar		hint.le.0.drq="0"
device		sbni
envvar		hint.sbni.0.at="isa"
envvar		hint.sbni.0.port="0x210"
envvar		hint.sbni.0.irq="0xefdead"
envvar		hint.sbni.0.flags="0"

#####################################################################

#
# Miscellaneous hardware:
#
# smapi: System Management Application Program Interface driver

device		smapi

#
# Laptop/Notebook options:
#
# See also:
#  apm under `Miscellaneous hardware'
# above.

# For older notebooks that signal a powerfail condition (external
# power supply dropped, or battery state low) by issuing an NMI:

options 	POWERFAIL_NMI	# make it beep instead of panicing

#
# I2C Bus
#
# Requires 'device iicbus'.
#
# Supported interfaces:
# glxiic: AMD Geode LX CS5536 System Management Bus
# pcf:	Philips PCF8584 ISA-bus controller
#
device		glxiic		# AMD Geode LX CS5536 System Management Bus
device		pcf
envvar		hint.pcf.0.at="isa"
envvar		hint.pcf.0.port="0x320"
envvar		hint.pcf.0.irq="5"

#
# glxsb is a driver for the Security Block in AMD Geode LX processors.
# Requires 'device crypto'.
#
device		glxsb		# AMD Geode LX Security Block

#####################################################################
# ABI Emulation

# Enable (32-bit) a.out binary support
options 	COMPAT_AOUT

#####################################################################
# VM OPTIONS

#
# Set the number of PV entries per process.  Increasing this can
# stop panics related to heavy use of shared memory.  However, that can
# (combined with large amounts of physical memory) cause panics at
# boot time due the kernel running out of VM space.
#
# If you're tweaking this, you might also want to increase the sysctls
# "vm.v_free_min", "vm.v_free_reserved", and "vm.v_free_target".
#
# The value below is the one more than the default.
#
options 	PMAP_SHPGPERPROC=201

#
# Number of initial kernel page table pages used for early bootstrap.
# This number should include enough pages to map the kernel, any
# modules or other data loaded with the kernel by the loader, and data
# structures allocated before the VM system is initialized such as the
# vm_page_t array.  Each page table page maps 4MB (2MB with PAE).
#
options 	NKPT=31

# KSTACK_PAGES is the number of memory pages to assign to the kernel
# stack of each thread.

options 	KSTACK_PAGES=5

# Enable detailed accounting by the PV entry allocator.

options 	PV_STATS

#####################################################################
# Items broken on i386 that are generally available elsewhere

# Device uses bus_read_8 and friends, so can't work. Remove it from lint.
nodevice	bnxt