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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
Ben Collins6bcb13b2008-06-18 14:04:35 -04008config X86_VERBOSE_BOOTUP
9 bool "Enable verbose x86 bootup info messages"
10 default y
Ingo Molnar8f9ca472009-02-05 16:21:53 +010011 ---help---
Ben Collins6bcb13b2008-06-18 14:04:35 -040012 Enables the informational output from the decompression stage
13 (e.g. bzImage) of the boot. If you disable this you will still
14 see errors. Disable this if you want silent bootup.
15
Linus Torvalds1da177e2005-04-16 15:20:36 -070016config EARLY_PRINTK
David Rientjes6a108a12011-01-20 14:44:16 -080017 bool "Early printk" if EXPERT
Linus Torvalds1da177e2005-04-16 15:20:36 -070018 default y
Ingo Molnar8f9ca472009-02-05 16:21:53 +010019 ---help---
Linus Torvalds1da177e2005-04-16 15:20:36 -070020 Write kernel log output directly into the VGA buffer or to a serial
21 port.
22
23 This is useful for kernel debugging when your machine crashes very
24 early before the console code is initialized. For normal operation
25 it is not recommended because it looks ugly and doesn't cooperate
26 with klogd/syslogd or the X server. You should normally N here,
27 unless you want to debug such a crash.
28
Yinghai Lu5c059172008-07-24 17:29:40 -070029config EARLY_PRINTK_DBGP
30 bool "Early printk via EHCI debug port"
Ingo Molnar97499862008-07-26 17:28:11 +020031 depends on EARLY_PRINTK && PCI
Ingo Molnar8f9ca472009-02-05 16:21:53 +010032 ---help---
Yinghai Lu5c059172008-07-24 17:29:40 -070033 Write kernel log output directly into the EHCI debug port.
34
35 This is useful for kernel debugging when your machine crashes very
36 early before the console code is initialized. For normal operation
37 it is not recommended because it looks ugly and doesn't cooperate
38 with klogd/syslogd or the X server. You should normally N here,
39 unless you want to debug such a crash. You need usb debug device.
40
Matt Fleming72548e82013-10-04 09:36:56 +010041config EARLY_PRINTK_EFI
42 bool "Early printk via the EFI framebuffer"
43 depends on EFI && EARLY_PRINTK
44 select FONT_SUPPORT
45 ---help---
46 Write kernel log output directly into the EFI framebuffer.
47
48 This is useful for kernel debugging when your machine crashes very
49 early before the console code is initialized.
50
Stephen Smalleye1a58322015-10-05 12:55:20 -040051config X86_PTDUMP_CORE
52 def_bool n
53
Arjan van de Ven926e5392008-04-17 17:40:45 +020054config X86_PTDUMP
Kees Cook8609d1b2015-11-19 17:07:55 -080055 tristate "Export kernel pagetable layout to userspace via debugfs"
H. Peter Anvinfe770bf02008-04-17 17:40:45 +020056 depends on DEBUG_KERNEL
Arjan van de Ven926e5392008-04-17 17:40:45 +020057 select DEBUG_FS
Stephen Smalleye1a58322015-10-05 12:55:20 -040058 select X86_PTDUMP_CORE
Ingo Molnar8f9ca472009-02-05 16:21:53 +010059 ---help---
Arjan van de Ven926e5392008-04-17 17:40:45 +020060 Say Y here if you want to show the kernel pagetable layout in a
61 debugfs file. This information is only useful for kernel developers
62 who are working in architecture specific areas of the kernel.
63 It is probably not a good idea to enable this feature in a production
64 kernel.
65 If in doubt, say "N"
66
Borislav Petkov11cc8512014-01-18 12:48:15 +010067config EFI_PGT_DUMP
68 bool "Dump the EFI pagetable"
Stephen Smalleye1a58322015-10-05 12:55:20 -040069 depends on EFI
70 select X86_PTDUMP_CORE
Borislav Petkov11cc8512014-01-18 12:48:15 +010071 ---help---
72 Enable this if you want to dump the EFI page table before
73 enabling virtual mode. This can be used to debug miscellaneous
74 issues with the mapping of the EFI runtime regions into that
75 table.
76
Ingo Molnaraba83912008-01-30 13:34:09 +010077config DEBUG_RODATA_TEST
Kees Cook9ccaf772016-02-17 14:41:14 -080078 bool "Testcase for the marking rodata read-only"
Ingo Molnar72370f22008-02-13 16:15:34 +010079 default y
Ingo Molnar8f9ca472009-02-05 16:21:53 +010080 ---help---
Kees Cook9ccaf772016-02-17 14:41:14 -080081 This option enables a testcase for the setting rodata read-only
82 as well as for the change_page_attr() infrastructure.
Ingo Molnaraba83912008-01-30 13:34:09 +010083 If in doubt, say "N"
84
Stephen Smalleye1a58322015-10-05 12:55:20 -040085config DEBUG_WX
86 bool "Warn on W+X mappings at boot"
Stephen Smalleye1a58322015-10-05 12:55:20 -040087 select X86_PTDUMP_CORE
88 ---help---
89 Generate a warning if any W+X mappings are found at boot.
90
91 This is useful for discovering cases where the kernel is leaving
92 W+X mappings after applying NX, as such mappings are a security risk.
93
94 Look for a message in dmesg output like this:
95
96 x86/mm: Checked W+X mappings: passed, no W+X pages found.
97
98 or like this, if the check failed:
99
100 x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found.
101
102 Note that even if the check fails, your kernel is possibly
103 still fine, as W+X mappings are not a security hole in
104 themselves, what they do is that they make the exploitation
105 of other unfixed kernel bugs easier.
106
107 There is no runtime or memory usage effect of this option
108 once the kernel has booted up - it's a one time check.
109
110 If in doubt, say "Y".
111
matthieu castet84e1c6b2010-11-16 22:35:16 +0100112config DEBUG_SET_MODULE_RONX
113 bool "Set loadable kernel module data as NX and text as RO"
114 depends on MODULES
115 ---help---
116 This option helps catch unintended modifications to loadable
117 kernel module's text and read-only data. It also prevents execution
118 of module data. Such protection may interfere with run-time code
119 patching and dynamic kernel tracing - and they might also protect
120 against certain classes of kernel exploits.
121 If in doubt, say "N".
122
Ingo Molnaraba83912008-01-30 13:34:09 +0100123config DEBUG_NX_TEST
124 tristate "Testcase for the NX non-executable stack feature"
125 depends on DEBUG_KERNEL && m
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100126 ---help---
Ingo Molnaraba83912008-01-30 13:34:09 +0100127 This option enables a testcase for the CPU NX capability
128 and the software setup of this feature.
129 If in doubt, say "N"
130
Andi Kleen102e41f2006-04-18 12:35:22 +0200131config DOUBLEFAULT
132 default y
David Rientjes6a108a12011-01-20 14:44:16 -0800133 bool "Enable doublefault exception handler" if EXPERT
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100134 ---help---
Randy Dunlapd013a272007-10-24 15:50:43 -0700135 This option allows trapping of rare doublefault exceptions that
136 would otherwise cause a system to silently reboot. Disabling this
137 option saves about 4k and might cause you much additional grey
138 hair.
139
Alex Shi3df32122012-06-28 09:02:20 +0800140config DEBUG_TLBFLUSH
141 bool "Set upper limit of TLB entries to flush one-by-one"
Paul Bollecd69aa62013-03-14 12:54:37 +0100142 depends on DEBUG_KERNEL
Alex Shi3df32122012-06-28 09:02:20 +0800143 ---help---
144
145 X86-only for now.
146
147 This option allows the user to tune the amount of TLB entries the
148 kernel flushes one-by-one instead of doing a full TLB flush. In
149 certain situations, the former is cheaper. This is controlled by the
150 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
151 to -1, the code flushes the whole TLB unconditionally. Otherwise,
152 for positive values of it, the kernel will use single TLB entry
153 invalidating instructions according to the following formula:
154
155 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
156
157 If in doubt, say "N".
158
Randy Dunlapd013a272007-10-24 15:50:43 -0700159config IOMMU_DEBUG
160 bool "Enable IOMMU debugging"
Joerg Roedel966396d2007-10-24 12:49:48 +0200161 depends on GART_IOMMU && DEBUG_KERNEL
Randy Dunlapd013a272007-10-24 15:50:43 -0700162 depends on X86_64
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100163 ---help---
Randy Dunlapd013a272007-10-24 15:50:43 -0700164 Force the IOMMU to on even when you have less than 4GB of
165 memory and add debugging code. On overflow always panic. And
166 allow to enable IOMMU leak tracing. Can be disabled at boot
167 time with iommu=noforce. This will also enable scatter gather
168 list merging. Currently not recommended for production
169 code. When you use it make sure you have a big enough
170 IOMMU/AGP aperture. Most of the options enabled by this can
171 be set more finegrained using the iommu= command line
Paul Bolle395cf962011-08-15 02:02:26 +0200172 options. See Documentation/x86/x86_64/boot-options.txt for more
Randy Dunlapd013a272007-10-24 15:50:43 -0700173 details.
174
Joerg Roedel2be69c72009-05-22 12:15:49 +0200175config IOMMU_STRESS
176 bool "Enable IOMMU stress-test mode"
177 ---help---
178 This option disables various optimizations in IOMMU related
179 code to do real stress testing of the IOMMU code. This option
180 will cause a performance drop and should only be enabled for
181 testing.
182
Randy Dunlapd013a272007-10-24 15:50:43 -0700183config IOMMU_LEAK
184 bool "IOMMU leak tracing"
FUJITA Tomonori19c1a6f2009-04-14 09:43:19 +0900185 depends on IOMMU_DEBUG && DMA_API_DEBUG
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100186 ---help---
Randy Dunlapd013a272007-10-24 15:50:43 -0700187 Add a simple leak tracer to the IOMMU code. This is useful when you
188 are debugging a buggy device driver that leaks IOMMU mappings.
189
Pekka Paalanen6bc5c362009-01-03 21:23:51 +0200190config HAVE_MMIOTRACE_SUPPORT
191 def_bool y
Pekka Paalanen8b7d89d2008-05-12 21:20:56 +0200192
Masami Hiramatsuca0e9ba2009-08-13 16:34:21 -0400193config X86_DECODER_SELFTEST
OGAWA Hirofumicbe5c342009-12-06 20:14:29 +0900194 bool "x86 instruction decoder selftest"
195 depends on DEBUG_KERNEL && KPROBES
Ingo Molnarf8f20232014-02-05 06:51:37 +0100196 depends on !COMPILE_TEST
Masami Hiramatsuca0e9ba2009-08-13 16:34:21 -0400197 ---help---
198 Perform x86 instruction decoder selftests at build time.
199 This option is useful for checking the sanity of x86 instruction
200 decoder code.
201 If unsure, say "N".
202
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100203#
204# IO delay types:
205#
206
207config IO_DELAY_TYPE_0X80
208 int
209 default "0"
210
211config IO_DELAY_TYPE_0XED
212 int
213 default "1"
214
215config IO_DELAY_TYPE_UDELAY
216 int
217 default "2"
218
219config IO_DELAY_TYPE_NONE
220 int
221 default "3"
222
223choice
224 prompt "IO delay type"
Ingo Molnarfd59e9e2008-02-17 20:20:24 +0100225 default IO_DELAY_0X80
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100226
227config IO_DELAY_0X80
228 bool "port 0x80 based port-IO delay [recommended]"
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100229 ---help---
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100230 This is the traditional Linux IO delay used for in/out_p.
231 It is the most tested hence safest selection here.
232
233config IO_DELAY_0XED
234 bool "port 0xed based port-IO delay"
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100235 ---help---
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100236 Use port 0xed as the IO delay. This frees up port 0x80 which is
237 often used as a hardware-debug port.
238
239config IO_DELAY_UDELAY
240 bool "udelay based port-IO delay"
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100241 ---help---
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100242 Use udelay(2) as the IO delay method. This provides the delay
243 while not having any side-effect on the IO port space.
244
245config IO_DELAY_NONE
246 bool "no port-IO delay"
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100247 ---help---
Ingo Molnar6e7c4022008-01-30 13:30:05 +0100248 No port-IO delay. Will break on old boxes that require port-IO
249 delay for certain operations. Should work on most new machines.
250
251endchoice
252
253if IO_DELAY_0X80
254config DEFAULT_IO_DELAY_TYPE
255 int
256 default IO_DELAY_TYPE_0X80
257endif
258
259if IO_DELAY_0XED
260config DEFAULT_IO_DELAY_TYPE
261 int
262 default IO_DELAY_TYPE_0XED
263endif
264
265if IO_DELAY_UDELAY
266config DEFAULT_IO_DELAY_TYPE
267 int
268 default IO_DELAY_TYPE_UDELAY
269endif
270
271if IO_DELAY_NONE
272config DEFAULT_IO_DELAY_TYPE
273 int
274 default IO_DELAY_TYPE_NONE
275endif
Rene Hermanb02aae92008-01-30 13:30:05 +0100276
Huang, Ying6d7d7432008-01-30 13:32:51 +0100277config DEBUG_BOOT_PARAMS
278 bool "Debug boot parameters"
279 depends on DEBUG_KERNEL
280 depends on DEBUG_FS
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100281 ---help---
Huang, Ying6d7d7432008-01-30 13:32:51 +0100282 This option will cause struct boot_params to be exported via debugfs.
283
Andi Kleen0c42f392008-01-30 13:33:42 +0100284config CPA_DEBUG
Ingo Molnar971a52d2008-02-06 22:39:45 +0100285 bool "CPA self-test code"
Ingo Molnarf316fe62008-01-30 13:34:04 +0100286 depends on DEBUG_KERNEL
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100287 ---help---
Ingo Molnar971a52d2008-02-06 22:39:45 +0100288 Do change_page_attr() self-tests every 30 seconds.
Andi Kleen0c42f392008-01-30 13:33:42 +0100289
Ingo Molnar60a3cdd2008-03-03 12:38:52 +0100290config OPTIMIZE_INLINING
291 bool "Allow gcc to uninline functions marked 'inline'"
Ingo Molnar8f9ca472009-02-05 16:21:53 +0100292 ---help---
Ingo Molnar60a3cdd2008-03-03 12:38:52 +0100293 This option determines if the kernel forces gcc to inline the functions
294 developers have marked 'inline'. Doing so takes away freedom from gcc to
295 do what it thinks is best, which is desirable for the gcc 3.x series of
296 compilers. The gcc 4.x series have a rewritten inlining algorithm and
Sitsofe Wheeler63fb7082008-10-11 20:27:53 +0100297 enabling this option will generate a smaller kernel there. Hopefully
298 this algorithm is so good that allowing gcc 4.x and above to make the
299 decision will become the default in the future. Until then this option
300 is there to test gcc for this.
Ingo Molnarc9af1e32008-04-30 08:48:45 +0200301
Ingo Molnar3f9b5cc2008-07-18 16:30:05 +0200302 If unsure, say N.
303
Andy Lutomirskia97439a2015-07-15 10:29:41 -0700304config DEBUG_ENTRY
305 bool "Debug low-level entry code"
306 depends on DEBUG_KERNEL
307 ---help---
308 This option enables sanity checks in x86's low-level entry code.
309 Some of these sanity checks may slow down kernel entries and
310 exits or otherwise impact performance.
311
312 This is currently used to help test NMI code.
313
314 If unsure, say N.
315
Don Zickus99e8b9c2011-10-13 15:14:26 -0400316config DEBUG_NMI_SELFTEST
317 bool "NMI Selftest"
Don Zickus4f941c52011-12-07 16:06:30 -0500318 depends on DEBUG_KERNEL && X86_LOCAL_APIC
Don Zickus99e8b9c2011-10-13 15:14:26 -0400319 ---help---
320 Enabling this option turns on a quick NMI selftest to verify
321 that the NMI behaves correctly.
322
323 This might help diagnose strange hangs that rely on NMI to
324 function properly.
325
326 If unsure, say N.
327
Bryan O'Donoghue28a375d2015-01-30 16:29:38 +0000328config DEBUG_IMR_SELFTEST
329 bool "Isolated Memory Region self test"
330 default n
331 depends on INTEL_IMR
332 ---help---
333 This option enables automated sanity testing of the IMR code.
334 Some simple tests are run to verify IMR bounds checking, alignment
335 and overlapping. This option is really only useful if you are
336 debugging an IMR memory map or are modifying the IMR code and want to
337 test your changes.
338
339 If unsure say N here.
340
Ingo Molnare97131a2015-05-05 11:34:49 +0200341config X86_DEBUG_FPU
342 bool "Debug the x86 FPU code"
343 depends on DEBUG_KERNEL
344 default y
345 ---help---
346 If this option is enabled then there will be extra sanity
347 checks and (boot time) debug printouts added to the kernel.
348 This debugging adds some small amount of runtime overhead
349 to the kernel.
350
351 If unsure, say N.
352
Srinivas Pandruvada956079e2015-05-06 12:15:54 -0700353config PUNIT_ATOM_DEBUG
354 tristate "ATOM Punit debug driver"
355 select DEBUG_FS
356 select IOSF_MBI
357 ---help---
358 This is a debug driver, which gets the power states
359 of all Punit North Complex devices. The power states of
360 each device is exposed as part of the debugfs interface.
361 The current power state can be read from
362 /sys/kernel/debug/punit_atom/dev_power_state
363
Ingo Molnarc9af1e32008-04-30 08:48:45 +0200364endmenu