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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
Adrian Bunk1b8a8e92007-10-29 13:49:36 +01009 bool "Early printk" if EMBEDDED && DEBUG_KERNEL && X86_32
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
37comment "Page alloc debug is incompatible with Software Suspend on i386"
Rafael J. Wysockib0cb1a12007-07-29 23:24:36 +020038 depends on DEBUG_KERNEL && HIBERNATION
Randy Dunlapd013a272007-10-24 15:50:43 -070039 depends on X86_32
Linus Torvalds1da177e2005-04-16 15:20:36 -070040
41config DEBUG_PAGEALLOC
Andrew Morton4a2f0ac2006-03-25 03:07:22 -080042 bool "Debug page memory allocations"
Rafael J. Wysockib0cb1a12007-07-29 23:24:36 +020043 depends on DEBUG_KERNEL && !HIBERNATION && !HUGETLBFS
Randy Dunlapd013a272007-10-24 15:50:43 -070044 depends on X86_32
Linus Torvalds1da177e2005-04-16 15:20:36 -070045 help
46 Unmap pages from the kernel linear mapping after free_pages().
47 This results in a large slowdown, but helps to find certain types
48 of memory corruptions.
49
Arjan van de Ven63aaf302006-01-06 00:12:02 -080050config DEBUG_RODATA
51 bool "Write protect kernel read-only data structures"
52 depends on DEBUG_KERNEL
53 help
54 Mark the kernel read-only data as write-protected in the pagetables,
55 in order to catch accidental (and incorrect) writes to such const
56 data. This option may have a slight performance impact because a
57 portion of the kernel code won't be covered by a 2MB TLB anymore.
58 If in doubt, say "N".
59
Linus Torvalds1da177e2005-04-16 15:20:36 -070060config 4KSTACKS
61 bool "Use 4Kb for kernel stacks instead of 8Kb"
62 depends on DEBUG_KERNEL
Randy Dunlapd013a272007-10-24 15:50:43 -070063 depends on X86_32
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 help
65 If you say Y here the kernel will use a 4Kb stacksize for the
66 kernel stack attached to each process/thread. This facilitates
67 running more threads on a system and also reduces the pressure
68 on the VM subsystem for higher order allocations. This option
69 will also use IRQ stacks to compensate for the reduced stackspace.
70
71config X86_FIND_SMP_CONFIG
Randy Dunlapd013a272007-10-24 15:50:43 -070072 def_bool y
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 depends on X86_LOCAL_APIC || X86_VOYAGER
Randy Dunlapd013a272007-10-24 15:50:43 -070074 depends on X86_32
Linus Torvalds1da177e2005-04-16 15:20:36 -070075
76config X86_MPPARSE
Randy Dunlapd013a272007-10-24 15:50:43 -070077 def_bool y
Sam Ravnborg6b0c3d42008-01-30 13:32:27 +010078 depends on (X86_32 && (X86_LOCAL_APIC && !X86_VISWS)) || X86_64
Linus Torvalds1da177e2005-04-16 15:20:36 -070079
Andi Kleen102e41f2006-04-18 12:35:22 +020080config DOUBLEFAULT
81 default y
82 bool "Enable doublefault exception handler" if EMBEDDED
Randy Dunlapd013a272007-10-24 15:50:43 -070083 depends on X86_32
Andi Kleen102e41f2006-04-18 12:35:22 +020084 help
Randy Dunlapd013a272007-10-24 15:50:43 -070085 This option allows trapping of rare doublefault exceptions that
86 would otherwise cause a system to silently reboot. Disabling this
87 option saves about 4k and might cause you much additional grey
88 hair.
89
90config IOMMU_DEBUG
91 bool "Enable IOMMU debugging"
Joerg Roedel966396d2007-10-24 12:49:48 +020092 depends on GART_IOMMU && DEBUG_KERNEL
Randy Dunlapd013a272007-10-24 15:50:43 -070093 depends on X86_64
94 help
95 Force the IOMMU to on even when you have less than 4GB of
96 memory and add debugging code. On overflow always panic. And
97 allow to enable IOMMU leak tracing. Can be disabled at boot
98 time with iommu=noforce. This will also enable scatter gather
99 list merging. Currently not recommended for production
100 code. When you use it make sure you have a big enough
101 IOMMU/AGP aperture. Most of the options enabled by this can
102 be set more finegrained using the iommu= command line
103 options. See Documentation/x86_64/boot-options.txt for more
104 details.
105
106config IOMMU_LEAK
107 bool "IOMMU leak tracing"
108 depends on DEBUG_KERNEL
109 depends on IOMMU_DEBUG
110 help
111 Add a simple leak tracer to the IOMMU code. This is useful when you
112 are debugging a buggy device driver that leaks IOMMU mappings.
113
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100114#
115# IO delay types:
116#
117
118config IO_DELAY_TYPE_0X80
119 int
120 default "0"
121
122config IO_DELAY_TYPE_0XED
123 int
124 default "1"
125
126config IO_DELAY_TYPE_UDELAY
127 int
128 default "2"
129
130config IO_DELAY_TYPE_NONE
131 int
132 default "3"
133
134choice
135 prompt "IO delay type"
Ingo Molnard0049e72008-01-30 13:30:05 +0100136 default IO_DELAY_0XED
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100137
138config IO_DELAY_0X80
139 bool "port 0x80 based port-IO delay [recommended]"
Rene Hermanb02aae92008-01-30 13:30:05 +0100140 help
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100141 This is the traditional Linux IO delay used for in/out_p.
142 It is the most tested hence safest selection here.
143
144config IO_DELAY_0XED
145 bool "port 0xed based port-IO delay"
146 help
147 Use port 0xed as the IO delay. This frees up port 0x80 which is
148 often used as a hardware-debug port.
149
150config IO_DELAY_UDELAY
151 bool "udelay based port-IO delay"
152 help
153 Use udelay(2) as the IO delay method. This provides the delay
154 while not having any side-effect on the IO port space.
155
156config IO_DELAY_NONE
157 bool "no port-IO delay"
158 help
159 No port-IO delay. Will break on old boxes that require port-IO
160 delay for certain operations. Should work on most new machines.
161
162endchoice
163
164if IO_DELAY_0X80
165config DEFAULT_IO_DELAY_TYPE
166 int
167 default IO_DELAY_TYPE_0X80
168endif
169
170if IO_DELAY_0XED
171config DEFAULT_IO_DELAY_TYPE
172 int
173 default IO_DELAY_TYPE_0XED
174endif
175
176if IO_DELAY_UDELAY
177config DEFAULT_IO_DELAY_TYPE
178 int
179 default IO_DELAY_TYPE_UDELAY
180endif
181
182if IO_DELAY_NONE
183config DEFAULT_IO_DELAY_TYPE
184 int
185 default IO_DELAY_TYPE_NONE
186endif
Rene Hermanb02aae92008-01-30 13:30:05 +0100187
Huang, Ying6d7d7432008-01-30 13:32:51 +0100188config DEBUG_BOOT_PARAMS
189 bool "Debug boot parameters"
190 depends on DEBUG_KERNEL
191 depends on DEBUG_FS
192 help
193 This option will cause struct boot_params to be exported via debugfs.
194
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195endmenu