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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
Ingo Molnard0926332008-07-18 00:26:59 +02008config STRICT_DEVMEM
Stefan Richter16104b552008-06-05 22:47:13 +02009 bool "Filter access to /dev/mem"
Ingo Molnar8f9ca472009-02-05 16:21:53 +010010 ---help---
Linus Torvaldsf2d0f1d2008-07-21 13:04:08 -070011 If this option is disabled, you allow userspace (root) access to all
Stefan Richter16104b552008-06-05 22:47:13 +020012 of memory, including kernel and userspace memory. Accidental
13 access to this is obviously disastrous, but specific access can
Ingo Molnard0926332008-07-18 00:26:59 +020014 be used by people debugging the kernel. Note that with PAT support
15 enabled, even in this case there are restrictions on /dev/mem
16 use due to the cache aliasing requirements.
Stefan Richter16104b552008-06-05 22:47:13 +020017
18 If this option is switched on, the /dev/mem file only allows
19 userspace access to PCI space and the BIOS code and data regions.
20 This is sufficient for dosemu and X and all common users of
21 /dev/mem.
22
23 If in doubt, say Y.
Arjan van de Venae531c22008-04-24 23:40:47 +020024
Ben Collins6bcb13b2008-06-18 14:04:35 -040025config X86_VERBOSE_BOOTUP
26 bool "Enable verbose x86 bootup info messages"
27 default y
Ingo Molnar8f9ca472009-02-05 16:21:53 +010028 ---help---
Ben Collins6bcb13b2008-06-18 14:04:35 -040029 Enables the informational output from the decompression stage
30 (e.g. bzImage) of the boot. If you disable this you will still
31 see errors. Disable this if you want silent bootup.
32
Linus Torvalds1da177e2005-04-16 15:20:36 -070033config EARLY_PRINTK
David Rientjes6a108a12011-01-20 14:44:16 -080034 bool "Early printk" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -070035 default y
Ingo Molnar8f9ca472009-02-05 16:21:53 +010036 ---help---
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 Write kernel log output directly into the VGA buffer or to a serial
38 port.
39
40 This is useful for kernel debugging when your machine crashes very
41 early before the console code is initialized. For normal operation
42 it is not recommended because it looks ugly and doesn't cooperate
43 with klogd/syslogd or the X server. You should normally N here,
44 unless you want to debug such a crash.
45
Alan Cox1ea7c672011-11-10 13:29:14 +000046config EARLY_PRINTK_INTEL_MID
47 bool "Early printk for Intel MID platform support"
48 depends on EARLY_PRINTK && X86_INTEL_MID
Feng Tangc20b5c32010-09-13 15:08:55 +080049
Yinghai Lu5c059172008-07-24 17:29:40 -070050config EARLY_PRINTK_DBGP
51 bool "Early printk via EHCI debug port"
Ingo Molnar97499862008-07-26 17:28:11 +020052 depends on EARLY_PRINTK && PCI
Ingo Molnar8f9ca472009-02-05 16:21:53 +010053 ---help---
Yinghai Lu5c059172008-07-24 17:29:40 -070054 Write kernel log output directly into the EHCI debug port.
55
56 This is useful for kernel debugging when your machine crashes very
57 early before the console code is initialized. For normal operation
58 it is not recommended because it looks ugly and doesn't cooperate
59 with klogd/syslogd or the X server. You should normally N here,
60 unless you want to debug such a crash. You need usb debug device.
61
Matt Fleming72548e82013-10-04 09:36:56 +010062config EARLY_PRINTK_EFI
63 bool "Early printk via the EFI framebuffer"
64 depends on EFI && EARLY_PRINTK
65 select FONT_SUPPORT
66 ---help---
67 Write kernel log output directly into the EFI framebuffer.
68
69 This is useful for kernel debugging when your machine crashes very
70 early before the console code is initialized.
71
Arjan van de Ven926e5392008-04-17 17:40:45 +020072config X86_PTDUMP
73 bool "Export kernel pagetable layout to userspace via debugfs"
H. Peter Anvinfe770bf02008-04-17 17:40:45 +020074 depends on DEBUG_KERNEL
Arjan van de Ven926e5392008-04-17 17:40:45 +020075 select DEBUG_FS
Ingo Molnar8f9ca472009-02-05 16:21:53 +010076 ---help---
Arjan van de Ven926e5392008-04-17 17:40:45 +020077 Say Y here if you want to show the kernel pagetable layout in a
78 debugfs file. This information is only useful for kernel developers
79 who are working in architecture specific areas of the kernel.
80 It is probably not a good idea to enable this feature in a production
81 kernel.
82 If in doubt, say "N"
83
Arjan van de Ven63aaf302006-01-06 00:12:02 -080084config DEBUG_RODATA
85 bool "Write protect kernel read-only data structures"
Ingo Molnar11201e62008-01-30 13:33:32 +010086 default y
Arjan van de Ven63aaf302006-01-06 00:12:02 -080087 depends on DEBUG_KERNEL
Ingo Molnar8f9ca472009-02-05 16:21:53 +010088 ---help---
Arjan van de Ven63aaf302006-01-06 00:12:02 -080089 Mark the kernel read-only data as write-protected in the pagetables,
90 in order to catch accidental (and incorrect) writes to such const
Ingo Molnar11201e62008-01-30 13:33:32 +010091 data. This is recommended so that we can catch kernel bugs sooner.
92 If in doubt, say "Y".
Arjan van de Ven63aaf302006-01-06 00:12:02 -080093
Ingo Molnaraba83912008-01-30 13:34:09 +010094config DEBUG_RODATA_TEST
95 bool "Testcase for the DEBUG_RODATA feature"
96 depends on DEBUG_RODATA
Ingo Molnar72370f22008-02-13 16:15:34 +010097 default y
Ingo Molnar8f9ca472009-02-05 16:21:53 +010098 ---help---
Ingo Molnaraba83912008-01-30 13:34:09 +010099 This option enables a testcase for the DEBUG_RODATA
100 feature as well as for the change_page_attr() infrastructure.
101 If in doubt, say "N"
102
matthieu castet84e1c6b2010-11-16 22:35:16 +0100103config DEBUG_SET_MODULE_RONX
104 bool "Set loadable kernel module data as NX and text as RO"
105 depends on MODULES
106 ---help---
107 This option helps catch unintended modifications to loadable
108 kernel module's text and read-only data. It also prevents execution
109 of module data. Such protection may interfere with run-time code
110 patching and dynamic kernel tracing - and they might also protect
111 against certain classes of kernel exploits.
112 If in doubt, say "N".
113
Ingo Molnaraba83912008-01-30 13:34:09 +0100114config DEBUG_NX_TEST
115 tristate "Testcase for the NX non-executable stack feature"
116 depends on DEBUG_KERNEL && m
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100117 ---help---
Ingo Molnaraba83912008-01-30 13:34:09 +0100118 This option enables a testcase for the CPU NX capability
119 and the software setup of this feature.
120 If in doubt, say "N"
121
Andi Kleen102e41f2006-04-18 12:35:22 +0200122config DOUBLEFAULT
123 default y
David Rientjes6a108a12011-01-20 14:44:16 -0800124 bool "Enable doublefault exception handler" if EXPERT
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100125 ---help---
Randy Dunlapd013a272007-10-24 15:50:43 -0700126 This option allows trapping of rare doublefault exceptions that
127 would otherwise cause a system to silently reboot. Disabling this
128 option saves about 4k and might cause you much additional grey
129 hair.
130
Alex Shi3df32122012-06-28 09:02:20 +0800131config DEBUG_TLBFLUSH
132 bool "Set upper limit of TLB entries to flush one-by-one"
Paul Bollecd69aa62013-03-14 12:54:37 +0100133 depends on DEBUG_KERNEL
Alex Shi3df32122012-06-28 09:02:20 +0800134 ---help---
135
136 X86-only for now.
137
138 This option allows the user to tune the amount of TLB entries the
139 kernel flushes one-by-one instead of doing a full TLB flush. In
140 certain situations, the former is cheaper. This is controlled by the
141 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
142 to -1, the code flushes the whole TLB unconditionally. Otherwise,
143 for positive values of it, the kernel will use single TLB entry
144 invalidating instructions according to the following formula:
145
146 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
147
148 If in doubt, say "N".
149
Randy Dunlapd013a272007-10-24 15:50:43 -0700150config IOMMU_DEBUG
151 bool "Enable IOMMU debugging"
Joerg Roedel966396d2007-10-24 12:49:48 +0200152 depends on GART_IOMMU && DEBUG_KERNEL
Randy Dunlapd013a272007-10-24 15:50:43 -0700153 depends on X86_64
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100154 ---help---
Randy Dunlapd013a272007-10-24 15:50:43 -0700155 Force the IOMMU to on even when you have less than 4GB of
156 memory and add debugging code. On overflow always panic. And
157 allow to enable IOMMU leak tracing. Can be disabled at boot
158 time with iommu=noforce. This will also enable scatter gather
159 list merging. Currently not recommended for production
160 code. When you use it make sure you have a big enough
161 IOMMU/AGP aperture. Most of the options enabled by this can
162 be set more finegrained using the iommu= command line
Paul Bolle395cf962011-08-15 02:02:26 +0200163 options. See Documentation/x86/x86_64/boot-options.txt for more
Randy Dunlapd013a272007-10-24 15:50:43 -0700164 details.
165
Joerg Roedel2be69c72009-05-22 12:15:49 +0200166config IOMMU_STRESS
167 bool "Enable IOMMU stress-test mode"
168 ---help---
169 This option disables various optimizations in IOMMU related
170 code to do real stress testing of the IOMMU code. This option
171 will cause a performance drop and should only be enabled for
172 testing.
173
Randy Dunlapd013a272007-10-24 15:50:43 -0700174config IOMMU_LEAK
175 bool "IOMMU leak tracing"
FUJITA Tomonori19c1a6f2009-04-14 09:43:19 +0900176 depends on IOMMU_DEBUG && DMA_API_DEBUG
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100177 ---help---
Randy Dunlapd013a272007-10-24 15:50:43 -0700178 Add a simple leak tracer to the IOMMU code. This is useful when you
179 are debugging a buggy device driver that leaks IOMMU mappings.
180
Pekka Paalanen6bc5c362009-01-03 21:23:51 +0200181config HAVE_MMIOTRACE_SUPPORT
182 def_bool y
Pekka Paalanen8b7d89d2008-05-12 21:20:56 +0200183
Masami Hiramatsuca0e9ba2009-08-13 16:34:21 -0400184config X86_DECODER_SELFTEST
OGAWA Hirofumicbe5c342009-12-06 20:14:29 +0900185 bool "x86 instruction decoder selftest"
186 depends on DEBUG_KERNEL && KPROBES
Ingo Molnarf8f20232014-02-05 06:51:37 +0100187 depends on !COMPILE_TEST
Masami Hiramatsuca0e9ba2009-08-13 16:34:21 -0400188 ---help---
189 Perform x86 instruction decoder selftests at build time.
190 This option is useful for checking the sanity of x86 instruction
191 decoder code.
192 If unsure, say "N".
193
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100194#
195# IO delay types:
196#
197
198config IO_DELAY_TYPE_0X80
199 int
200 default "0"
201
202config IO_DELAY_TYPE_0XED
203 int
204 default "1"
205
206config IO_DELAY_TYPE_UDELAY
207 int
208 default "2"
209
210config IO_DELAY_TYPE_NONE
211 int
212 default "3"
213
214choice
215 prompt "IO delay type"
Ingo Molnarfd59e9e2008-02-17 20:20:24 +0100216 default IO_DELAY_0X80
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100217
218config IO_DELAY_0X80
219 bool "port 0x80 based port-IO delay [recommended]"
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100220 ---help---
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100221 This is the traditional Linux IO delay used for in/out_p.
222 It is the most tested hence safest selection here.
223
224config IO_DELAY_0XED
225 bool "port 0xed based port-IO delay"
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100226 ---help---
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100227 Use port 0xed as the IO delay. This frees up port 0x80 which is
228 often used as a hardware-debug port.
229
230config IO_DELAY_UDELAY
231 bool "udelay based port-IO delay"
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100232 ---help---
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100233 Use udelay(2) as the IO delay method. This provides the delay
234 while not having any side-effect on the IO port space.
235
236config IO_DELAY_NONE
237 bool "no port-IO delay"
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100238 ---help---
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100239 No port-IO delay. Will break on old boxes that require port-IO
240 delay for certain operations. Should work on most new machines.
241
242endchoice
243
244if IO_DELAY_0X80
245config DEFAULT_IO_DELAY_TYPE
246 int
247 default IO_DELAY_TYPE_0X80
248endif
249
250if IO_DELAY_0XED
251config DEFAULT_IO_DELAY_TYPE
252 int
253 default IO_DELAY_TYPE_0XED
254endif
255
256if IO_DELAY_UDELAY
257config DEFAULT_IO_DELAY_TYPE
258 int
259 default IO_DELAY_TYPE_UDELAY
260endif
261
262if IO_DELAY_NONE
263config DEFAULT_IO_DELAY_TYPE
264 int
265 default IO_DELAY_TYPE_NONE
266endif
Rene Hermanb02aae92008-01-30 13:30:05 +0100267
Huang, Ying6d7d7432008-01-30 13:32:51 +0100268config DEBUG_BOOT_PARAMS
269 bool "Debug boot parameters"
270 depends on DEBUG_KERNEL
271 depends on DEBUG_FS
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100272 ---help---
Huang, Ying6d7d7432008-01-30 13:32:51 +0100273 This option will cause struct boot_params to be exported via debugfs.
274
Andi Kleen0c42f392008-01-30 13:33:42 +0100275config CPA_DEBUG
Ingo Molnar971a52d2008-02-06 22:39:45 +0100276 bool "CPA self-test code"
Ingo Molnarf316fe62008-01-30 13:34:04 +0100277 depends on DEBUG_KERNEL
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100278 ---help---
Ingo Molnar971a52d2008-02-06 22:39:45 +0100279 Do change_page_attr() self-tests every 30 seconds.
Andi Kleen0c42f392008-01-30 13:33:42 +0100280
Ingo Molnar60a3cdd2008-03-03 12:38:52 +0100281config OPTIMIZE_INLINING
282 bool "Allow gcc to uninline functions marked 'inline'"
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100283 ---help---
Ingo Molnar60a3cdd2008-03-03 12:38:52 +0100284 This option determines if the kernel forces gcc to inline the functions
285 developers have marked 'inline'. Doing so takes away freedom from gcc to
286 do what it thinks is best, which is desirable for the gcc 3.x series of
287 compilers. The gcc 4.x series have a rewritten inlining algorithm and
Sitsofe Wheeler63fb7082008-10-11 20:27:53 +0100288 enabling this option will generate a smaller kernel there. Hopefully
289 this algorithm is so good that allowing gcc 4.x and above to make the
290 decision will become the default in the future. Until then this option
291 is there to test gcc for this.
Ingo Molnarc9af1e32008-04-30 08:48:45 +0200292
Ingo Molnar3f9b5cc2008-07-18 16:30:05 +0200293 If unsure, say N.
294
Don Zickus99e8b9c2011-10-13 15:14:26 -0400295config DEBUG_NMI_SELFTEST
296 bool "NMI Selftest"
Don Zickus4f941c52011-12-07 16:06:30 -0500297 depends on DEBUG_KERNEL && X86_LOCAL_APIC
Don Zickus99e8b9c2011-10-13 15:14:26 -0400298 ---help---
299 Enabling this option turns on a quick NMI selftest to verify
300 that the NMI behaves correctly.
301
302 This might help diagnose strange hangs that rely on NMI to
303 function properly.
304
305 If unsure, say N.
306
Borislav Petkov5700f742013-06-09 12:07:32 +0200307config X86_DEBUG_STATIC_CPU_HAS
308 bool "Debug alternatives"
309 depends on DEBUG_KERNEL
310 ---help---
311 This option causes additional code to be generated which
312 fails if static_cpu_has() is used before alternatives have
313 run.
314
315 If unsure, say N.
316
Ingo Molnarc9af1e32008-04-30 08:48:45 +0200317endmenu