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Linus Torvalds1da177e2005-04-16 15:20:36 -07001menu "Kernel hacking"
2
Ingo Molnar55f327f2006-07-03 00:24:43 -07003config TRACE_IRQFLAGS_SUPPORT
Randy Dunlapd013a272007-10-24 15:50:43 -07004 def_bool y
Ingo Molnar55f327f2006-07-03 00:24:43 -07005
Linus Torvalds1da177e2005-04-16 15:20:36 -07006source "lib/Kconfig.debug"
7
8config EARLY_PRINTK
Ingo Molnar076f9772008-01-30 13:33:06 +01009 bool "Early printk" if EMBEDDED
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 default y
11 help
12 Write kernel log output directly into the VGA buffer or to a serial
13 port.
14
15 This is useful for kernel debugging when your machine crashes very
16 early before the console code is initialized. For normal operation
17 it is not recommended because it looks ugly and doesn't cooperate
18 with klogd/syslogd or the X server. You should normally N here,
19 unless you want to debug such a crash.
20
21config DEBUG_STACKOVERFLOW
22 bool "Check for stack overflows"
23 depends on DEBUG_KERNEL
Adrian Bunkdab175f2005-07-27 11:44:23 -070024 help
25 This option will cause messages to be printed if free stack space
26 drops below a certain limit.
Linus Torvalds1da177e2005-04-16 15:20:36 -070027
Linus Torvalds1da177e2005-04-16 15:20:36 -070028config DEBUG_STACK_USAGE
29 bool "Stack utilization instrumentation"
30 depends on DEBUG_KERNEL
31 help
32 Enables the display of the minimum amount of free stack which each
33 task has ever had available in the sysrq-T and sysrq-P debug output.
34
35 This option will slow down process creation somewhat.
36
Linus Torvalds1da177e2005-04-16 15:20:36 -070037config DEBUG_PAGEALLOC
Andrew Morton4a2f0ac2006-03-25 03:07:22 -080038 bool "Debug page memory allocations"
Thomas Gleixnerb1d95f42008-02-09 23:24:09 +010039 depends on DEBUG_KERNEL
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 help
41 Unmap pages from the kernel linear mapping after free_pages().
42 This results in a large slowdown, but helps to find certain types
43 of memory corruptions.
44
travis@sgi.comc49a4952008-01-30 13:33:22 +010045config DEBUG_PER_CPU_MAPS
46 bool "Debug access to per_cpu maps"
47 depends on DEBUG_KERNEL
48 depends on X86_64_SMP
49 default n
50 help
51 Say Y to verify that the per_cpu map being accessed has
52 been setup. Adds a fair amount of code to kernel memory
53 and decreases performance.
54
55 Say N if unsure.
56
Arjan van de Ven63aaf302006-01-06 00:12:02 -080057config DEBUG_RODATA
58 bool "Write protect kernel read-only data structures"
Ingo Molnar11201e62008-01-30 13:33:32 +010059 default y
Arjan van de Ven63aaf302006-01-06 00:12:02 -080060 depends on DEBUG_KERNEL
61 help
62 Mark the kernel read-only data as write-protected in the pagetables,
63 in order to catch accidental (and incorrect) writes to such const
Ingo Molnar11201e62008-01-30 13:33:32 +010064 data. This is recommended so that we can catch kernel bugs sooner.
65 If in doubt, say "Y".
Arjan van de Ven63aaf302006-01-06 00:12:02 -080066
Ingo Molnaraba83912008-01-30 13:34:09 +010067config DEBUG_RODATA_TEST
68 bool "Testcase for the DEBUG_RODATA feature"
69 depends on DEBUG_RODATA
70 help
71 This option enables a testcase for the DEBUG_RODATA
72 feature as well as for the change_page_attr() infrastructure.
73 If in doubt, say "N"
74
75config DEBUG_NX_TEST
76 tristate "Testcase for the NX non-executable stack feature"
77 depends on DEBUG_KERNEL && m
78 help
79 This option enables a testcase for the CPU NX capability
80 and the software setup of this feature.
81 If in doubt, say "N"
82
Linus Torvalds1da177e2005-04-16 15:20:36 -070083config 4KSTACKS
84 bool "Use 4Kb for kernel stacks instead of 8Kb"
85 depends on DEBUG_KERNEL
Randy Dunlapd013a272007-10-24 15:50:43 -070086 depends on X86_32
Linus Torvalds1da177e2005-04-16 15:20:36 -070087 help
88 If you say Y here the kernel will use a 4Kb stacksize for the
89 kernel stack attached to each process/thread. This facilitates
90 running more threads on a system and also reduces the pressure
91 on the VM subsystem for higher order allocations. This option
92 will also use IRQ stacks to compensate for the reduced stackspace.
93
94config X86_FIND_SMP_CONFIG
Randy Dunlapd013a272007-10-24 15:50:43 -070095 def_bool y
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 depends on X86_LOCAL_APIC || X86_VOYAGER
Randy Dunlapd013a272007-10-24 15:50:43 -070097 depends on X86_32
Linus Torvalds1da177e2005-04-16 15:20:36 -070098
99config X86_MPPARSE
Randy Dunlapd013a272007-10-24 15:50:43 -0700100 def_bool y
Sam Ravnborg6b0c3d42008-01-30 13:32:27 +0100101 depends on (X86_32 && (X86_LOCAL_APIC && !X86_VISWS)) || X86_64
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102
Andi Kleen102e41f2006-04-18 12:35:22 +0200103config DOUBLEFAULT
104 default y
105 bool "Enable doublefault exception handler" if EMBEDDED
Randy Dunlapd013a272007-10-24 15:50:43 -0700106 depends on X86_32
Andi Kleen102e41f2006-04-18 12:35:22 +0200107 help
Randy Dunlapd013a272007-10-24 15:50:43 -0700108 This option allows trapping of rare doublefault exceptions that
109 would otherwise cause a system to silently reboot. Disabling this
110 option saves about 4k and might cause you much additional grey
111 hair.
112
113config IOMMU_DEBUG
114 bool "Enable IOMMU debugging"
Joerg Roedel966396d2007-10-24 12:49:48 +0200115 depends on GART_IOMMU && DEBUG_KERNEL
Randy Dunlapd013a272007-10-24 15:50:43 -0700116 depends on X86_64
117 help
118 Force the IOMMU to on even when you have less than 4GB of
119 memory and add debugging code. On overflow always panic. And
120 allow to enable IOMMU leak tracing. Can be disabled at boot
121 time with iommu=noforce. This will also enable scatter gather
122 list merging. Currently not recommended for production
123 code. When you use it make sure you have a big enough
124 IOMMU/AGP aperture. Most of the options enabled by this can
125 be set more finegrained using the iommu= command line
126 options. See Documentation/x86_64/boot-options.txt for more
127 details.
128
129config IOMMU_LEAK
130 bool "IOMMU leak tracing"
131 depends on DEBUG_KERNEL
132 depends on IOMMU_DEBUG
133 help
134 Add a simple leak tracer to the IOMMU code. This is useful when you
135 are debugging a buggy device driver that leaks IOMMU mappings.
136
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100137#
138# IO delay types:
139#
140
141config IO_DELAY_TYPE_0X80
142 int
143 default "0"
144
145config IO_DELAY_TYPE_0XED
146 int
147 default "1"
148
149config IO_DELAY_TYPE_UDELAY
150 int
151 default "2"
152
153config IO_DELAY_TYPE_NONE
154 int
155 default "3"
156
157choice
158 prompt "IO delay type"
Ingo Molnarfd59e9e2008-02-17 20:20:24 +0100159 default IO_DELAY_0X80
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100160
161config IO_DELAY_0X80
162 bool "port 0x80 based port-IO delay [recommended]"
Rene Hermanb02aae92008-01-30 13:30:05 +0100163 help
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100164 This is the traditional Linux IO delay used for in/out_p.
165 It is the most tested hence safest selection here.
166
167config IO_DELAY_0XED
168 bool "port 0xed based port-IO delay"
169 help
170 Use port 0xed as the IO delay. This frees up port 0x80 which is
171 often used as a hardware-debug port.
172
173config IO_DELAY_UDELAY
174 bool "udelay based port-IO delay"
175 help
176 Use udelay(2) as the IO delay method. This provides the delay
177 while not having any side-effect on the IO port space.
178
179config IO_DELAY_NONE
180 bool "no port-IO delay"
181 help
182 No port-IO delay. Will break on old boxes that require port-IO
183 delay for certain operations. Should work on most new machines.
184
185endchoice
186
187if IO_DELAY_0X80
188config DEFAULT_IO_DELAY_TYPE
189 int
190 default IO_DELAY_TYPE_0X80
191endif
192
193if IO_DELAY_0XED
194config DEFAULT_IO_DELAY_TYPE
195 int
196 default IO_DELAY_TYPE_0XED
197endif
198
199if IO_DELAY_UDELAY
200config DEFAULT_IO_DELAY_TYPE
201 int
202 default IO_DELAY_TYPE_UDELAY
203endif
204
205if IO_DELAY_NONE
206config DEFAULT_IO_DELAY_TYPE
207 int
208 default IO_DELAY_TYPE_NONE
209endif
Rene Hermanb02aae92008-01-30 13:30:05 +0100210
Huang, Ying6d7d7432008-01-30 13:32:51 +0100211config DEBUG_BOOT_PARAMS
212 bool "Debug boot parameters"
213 depends on DEBUG_KERNEL
214 depends on DEBUG_FS
215 help
216 This option will cause struct boot_params to be exported via debugfs.
217
Andi Kleen0c42f392008-01-30 13:33:42 +0100218config CPA_DEBUG
Ingo Molnar971a52d2008-02-06 22:39:45 +0100219 bool "CPA self-test code"
Ingo Molnarf316fe62008-01-30 13:34:04 +0100220 depends on DEBUG_KERNEL
Andi Kleen0c42f392008-01-30 13:33:42 +0100221 help
Ingo Molnar971a52d2008-02-06 22:39:45 +0100222 Do change_page_attr() self-tests every 30 seconds.
Andi Kleen0c42f392008-01-30 13:33:42 +0100223
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224endmenu