xref: /freebsd/sys/i386/conf/NOTES (revision 6580f5c38dd5b01aeeaed16b370f1a12423437f0)
1#
2# NOTES -- Lines that can be cut/pasted into kernel and hints configs.
3#
4# This file contains machine dependent kernel configuration notes.  For
5# machine independent notes, look in /sys/conf/NOTES.  For notes shared
6# with amd64, look in /sys/x86/conf/NOTES.
7#
8#
9
10
11#####################################################################
12# SMP OPTIONS:
13#
14# The apic device enables the use of the I/O APIC for interrupt delivery.
15# The apic device can be used in both UP and SMP kernels, but is required
16# for SMP kernels.  Thus, the apic device is not strictly an SMP option,
17# but it is a prerequisite for SMP.
18#
19# Notes:
20#
21# HTT CPUs should only be used if they are enabled in the BIOS.  For
22# the ACPI case, ACPI only correctly tells us about any HTT CPUs if
23# they are enabled.  However, most HTT systems do not list HTT CPUs
24# in the MP Table if they are enabled, thus we guess at the HTT CPUs
25# for the MP Table case.  However, we shouldn't try to guess and use
26# these CPUs if HTT is disabled.  Thus, HTT guessing is only enabled
27# for the MP Table if the user explicitly asks for it via the
28# MPTABLE_FORCE_HTT option.  Do NOT use this option if you have HTT
29# disabled in your BIOS.
30#
31# IPI_PREEMPTION instructs the kernel to preempt threads running on other
32# CPUS if needed.  Relies on the PREEMPTION option
33
34# Mandatory:
35device		apic			# I/O apic
36
37# Optional:
38options 	MPTABLE_FORCE_HTT	# Enable HTT CPUs with the MP Table
39
40
41#####################################################################
42# CPU OPTIONS
43
44#
45# You must specify at least one CPU (the one you intend to run on);
46# deleting the specification for CPUs you don't need to use may make
47# parts of the system run faster.
48#
49cpu		I486_CPU
50cpu		I586_CPU		# aka Pentium(tm)
51cpu		I686_CPU		# aka Pentium Pro(tm)
52
53#
54# Options for CPU features.
55#
56# CPU_ATHLON_SSE_HACK tries to enable SSE instructions when the BIOS has
57# forgotten to enable them.
58#
59# CPU_BLUELIGHTNING_3X enables triple-clock mode on IBM Blue Lightning
60# CPU if CPU supports it.  The default is double-clock mode on
61# BlueLightning CPU box.
62#
63# CPU_BLUELIGHTNING_FPU_OP_CACHE enables FPU operand cache on IBM
64# BlueLightning CPU.  It works only with Cyrix FPU, and this option
65# should not be used with Intel FPU.
66#
67# CPU_BTB_EN enables branch target buffer on Cyrix 5x86 (NOTE 1).
68#
69# CPU_CYRIX_NO_LOCK enables weak locking for the entire address space
70# of Cyrix 6x86 and 6x86MX CPUs by setting the NO_LOCK bit of CCR1.
71# Otherwise, the NO_LOCK bit of CCR1 is cleared.  (NOTE 3)
72#
73# CPU_DIRECT_MAPPED_CACHE sets L1 cache of Cyrix 486DLC CPU in direct
74# mapped mode.  Default is 2-way set associative mode.
75#
76# CPU_DISABLE_5X86_LSSER disables load store serialize (i.e., enables
77# reorder).  This option should not be used if you use memory mapped
78# I/O device(s).
79#
80# CPU_ELAN enables support for AMDs ElanSC520 CPU.
81#    CPU_ELAN_PPS enables precision timestamp code.
82#    CPU_ELAN_XTAL sets the clock crystal frequency in Hz.
83#
84# CPU_ENABLE_LONGRUN enables support for Transmeta Crusoe LongRun
85# technology which allows to restrict power consumption of the CPU by
86# using group of hw.crusoe.* sysctls.
87#
88# CPU_FASTER_5X86_FPU enables faster FPU exception handler.
89#
90# CPU_GEODE is for the SC1100 Geode embedded processor.  This option
91# is necessary because the i8254 timecounter is toast.
92#
93# CPU_I486_ON_386 enables CPU cache on i486 based CPU upgrade products
94# for i386 machines.
95#
96# CPU_IORT defines I/O clock delay time (NOTE 1).  Default values of
97# I/O clock delay time on Cyrix 5x86 and 6x86 are 0 and 7,respectively
98# (no clock delay).
99#
100# CPU_L2_LATENCY specifies the L2 cache latency value.  This option is used
101# only when CPU_PPRO2CELERON is defined and Mendocino Celeron is detected.
102# The default value is 5.
103#
104# CPU_LOOP_EN prevents flushing the prefetch buffer if the destination
105# of a jump is already present in the prefetch buffer on Cyrix 5x86(NOTE
106# 1).
107#
108# CPU_PPRO2CELERON enables L2 cache of Mendocino Celeron CPUs.  This option
109# is useful when you use Socket 8 to Socket 370 converter, because most Pentium
110# Pro BIOSs do not enable L2 cache of Mendocino Celeron CPUs.
111#
112# CPU_RSTK_EN enables return stack on Cyrix 5x86 (NOTE 1).
113#
114# CPU_SOEKRIS enables support www.soekris.com hardware.
115#
116# CPU_SUSP_HLT enables suspend on HALT.  If this option is set, CPU
117# enters suspend mode following execution of HALT instruction.
118#
119# CPU_UPGRADE_HW_CACHE eliminates unneeded cache flush instruction(s).
120#
121# CPU_WT_ALLOC enables write allocation on Cyrix 6x86/6x86MX and AMD
122# K5/K6/K6-2 CPUs.
123#
124# CYRIX_CACHE_WORKS enables CPU cache on Cyrix 486 CPUs with cache
125# flush at hold state.
126#
127# CYRIX_CACHE_REALLY_WORKS enables (1) CPU cache on Cyrix 486 CPUs
128# without cache flush at hold state, and (2) write-back CPU cache on
129# Cyrix 6x86 whose revision < 2.7 (NOTE 2).
130#
131# NO_F00F_HACK disables the hack that prevents Pentiums (and ONLY
132# Pentiums) from locking up when a LOCK CMPXCHG8B instruction is
133# executed.  This option is only needed if I586_CPU is also defined,
134# and should be included for any non-Pentium CPU that defines it.
135#
136# NO_MEMORY_HOLE is an optimisation for systems with AMD K6 processors
137# which indicates that the 15-16MB range is *definitely* not being
138# occupied by an ISA memory hole.
139#
140# NOTE 1: The options, CPU_BTB_EN, CPU_LOOP_EN, CPU_IORT,
141# CPU_LOOP_EN and CPU_RSTK_EN should not be used because of CPU bugs.
142# These options may crash your system.
143#
144# NOTE 2: If CYRIX_CACHE_REALLY_WORKS is not set, CPU cache is enabled
145# in write-through mode when revision < 2.7.  If revision of Cyrix
146# 6x86 >= 2.7, CPU cache is always enabled in write-back mode.
147#
148# NOTE 3: This option may cause failures for software that requires
149# locked cycles in order to operate correctly.
150#
151options 	CPU_ATHLON_SSE_HACK
152options 	CPU_BLUELIGHTNING_3X
153options 	CPU_BLUELIGHTNING_FPU_OP_CACHE
154options 	CPU_BTB_EN
155options 	CPU_DIRECT_MAPPED_CACHE
156options 	CPU_DISABLE_5X86_LSSER
157options 	CPU_ELAN
158options 	CPU_ELAN_PPS
159options 	CPU_ELAN_XTAL=32768000
160options 	CPU_ENABLE_LONGRUN
161options 	CPU_FASTER_5X86_FPU
162options 	CPU_GEODE
163options 	CPU_I486_ON_386
164options 	CPU_IORT
165options 	CPU_L2_LATENCY=5
166options 	CPU_LOOP_EN
167options 	CPU_PPRO2CELERON
168options 	CPU_RSTK_EN
169options 	CPU_SOEKRIS
170options 	CPU_SUSP_HLT
171options 	CPU_UPGRADE_HW_CACHE
172options 	CPU_WT_ALLOC
173options 	CYRIX_CACHE_WORKS
174options 	CYRIX_CACHE_REALLY_WORKS
175#options 	NO_F00F_HACK
176
177# Debug options
178options 	NPX_DEBUG	# enable npx debugging
179
180#
181# PERFMON causes the driver for Pentium/Pentium Pro performance counters
182# to be compiled.  See perfmon(4) for more information.
183#
184options 	PERFMON
185
186#
187# Hints for the non-optional Numeric Processing eXtension driver.
188envvar		hint.npx.0.flags="0x0"
189envvar		hint.npx.0.irq="13"
190
191#
192# `flags' for npx0:
193#	0x01	don't use the npx registers to optimize bcopy.
194#	0x02	don't use the npx registers to optimize bzero.
195#	0x04	don't use the npx registers to optimize copyin or copyout.
196# The npx registers are normally used to optimize copying and zeroing when
197# all of the following conditions are satisfied:
198#	I586_CPU is an option
199#	the cpu is an i586 (perhaps not a Pentium)
200#	the probe for npx0 succeeds
201#	INT 16 exception handling works.
202# Then copying and zeroing using the npx registers is normally 30-100% faster.
203# The flags can be used to control cases where it doesn't work or is slower.
204# Setting them at boot time using hints works right (the optimizations
205# are not used until later in the bootstrap when npx0 is attached).
206# Flag 0x08 automatically disables the i586 optimized routines.
207#
208
209
210#####################################################################
211# HARDWARE DEVICE CONFIGURATION
212
213#
214# Optional devices:
215#
216
217# 3Dfx Voodoo Graphics, Voodoo II /dev/3dfx CDEV support.  This will create
218# the /dev/3dfx0 device to work with glide implementations.  This should get
219# linked to /dev/3dfx and /dev/voodoo.  Note that this is not the same as
220# the tdfx DRI module from XFree86 and is completely unrelated.
221#
222# To enable Linuxulator support, one must also load linux.ko and tdfx_linux.ko.
223
224device		tdfx			# Enable 3Dfx Voodoo support
225
226#
227# RAID adapters
228#
229device		pst
230
231#
232# Adaptec by PMC RAID controllers, Series 6/7/8 and upcoming families
233device		aacraid		# Container interface, CAM required
234
235#
236# Network interfaces:
237#
238
239# sbni: Granch SBNI12-xx ISA and PCI adapters
240# vmx:	VMware VMXNET3 Ethernet (BSD open source)
241# wpi:	Intel 3945ABG Wireless LAN controller
242#	Requires the wpi firmware module
243
244# Order for ISA/EISA devices is important here
245
246envvar		hint.cs.0.at="isa"
247envvar		hint.cs.0.port="0x300"
248envvar		hint.ed.0.at="isa"
249envvar		hint.ed.0.port="0x280"
250envvar		hint.ed.0.irq="5"
251envvar		hint.ed.0.maddr="0xd8000"
252# Hint for the i386-only ISA front-end of le(4).
253envvar		hint.le.0.at="isa"
254envvar		hint.le.0.port="0x280"
255envvar		hint.le.0.irq="10"
256envvar		hint.le.0.drq="0"
257device		sbni
258envvar		hint.sbni.0.at="isa"
259envvar		hint.sbni.0.port="0x210"
260envvar		hint.sbni.0.irq="0xefdead"
261envvar		hint.sbni.0.flags="0"
262
263#####################################################################
264
265#
266# Miscellaneous hardware:
267#
268# smapi: System Management Application Program Interface driver
269
270device		smapi
271
272#
273# Laptop/Notebook options:
274#
275# See also:
276#  apm under `Miscellaneous hardware'
277# above.
278
279# For older notebooks that signal a powerfail condition (external
280# power supply dropped, or battery state low) by issuing an NMI:
281
282options 	POWERFAIL_NMI	# make it beep instead of panicing
283
284#
285# I2C Bus
286#
287# Requires 'device iicbus'.
288#
289# Supported interfaces:
290# glxiic: AMD Geode LX CS5536 System Management Bus
291# pcf:	Philips PCF8584 ISA-bus controller
292#
293device		glxiic		# AMD Geode LX CS5536 System Management Bus
294device		pcf
295envvar		hint.pcf.0.at="isa"
296envvar		hint.pcf.0.port="0x320"
297envvar		hint.pcf.0.irq="5"
298
299#
300# glxsb is a driver for the Security Block in AMD Geode LX processors.
301# Requires 'device crypto'.
302#
303device		glxsb		# AMD Geode LX Security Block
304
305#####################################################################
306# ABI Emulation
307
308# Enable (32-bit) a.out binary support
309options 	COMPAT_AOUT
310
311#####################################################################
312# VM OPTIONS
313
314#
315# Set the number of PV entries per process.  Increasing this can
316# stop panics related to heavy use of shared memory.  However, that can
317# (combined with large amounts of physical memory) cause panics at
318# boot time due the kernel running out of VM space.
319#
320# If you're tweaking this, you might also want to increase the sysctls
321# "vm.v_free_min", "vm.v_free_reserved", and "vm.v_free_target".
322#
323# The value below is the one more than the default.
324#
325options 	PMAP_SHPGPERPROC=201
326
327#
328# Number of initial kernel page table pages used for early bootstrap.
329# This number should include enough pages to map the kernel, any
330# modules or other data loaded with the kernel by the loader, and data
331# structures allocated before the VM system is initialized such as the
332# vm_page_t array.  Each page table page maps 4MB (2MB with PAE).
333#
334options 	NKPT=31
335
336# KSTACK_PAGES is the number of memory pages to assign to the kernel
337# stack of each thread.
338
339options 	KSTACK_PAGES=5
340
341# Enable detailed accounting by the PV entry allocator.
342
343options 	PV_STATS
344
345#####################################################################
346# Items broken on i386 that are generally available elsewhere
347
348# Device uses bus_read_8 and friends, so can't work. Remove it from lint.
349nodevice	bnxt
350