1menu "Kernel hacking"
  2
  3config TRACE_IRQFLAGS_SUPPORT
  4	def_bool y
  5
  6source "lib/Kconfig.debug"
 
  7
  8config X86_VERBOSE_BOOTUP
  9	bool "Enable verbose x86 bootup info messages"
 10	default y
 11	---help---
 12	  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
 16config EARLY_PRINTK
 17	bool "Early printk" if EXPERT
 18	default y
 19	---help---
 20	  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
 29config EARLY_PRINTK_DBGP
 30	bool "Early printk via EHCI debug port"
 31	depends on EARLY_PRINTK && PCI
 
 32	---help---
 33	  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
 41config 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
 51config X86_PTDUMP_CORE
 52	def_bool n
 53
 54config X86_PTDUMP
 55	tristate "Export kernel pagetable layout to userspace via debugfs"
 56	depends on DEBUG_KERNEL
 57	select DEBUG_FS
 58	select X86_PTDUMP_CORE
 59	---help---
 60	  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
 67config EFI_PGT_DUMP
 68	bool "Dump the EFI pagetable"
 69	depends on EFI
 70	select X86_PTDUMP_CORE
 71	---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
 77config DEBUG_RODATA_TEST
 78	bool "Testcase for the marking rodata read-only"
 79	default y
 80	---help---
 81	  This option enables a testcase for the setting rodata read-only
 82	  as well as for the change_page_attr() infrastructure.
 83	  If in doubt, say "N"
 84
 85config DEBUG_WX
 86	bool "Warn on W+X mappings at boot"
 87	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
112config 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
123config DEBUG_NX_TEST
124	tristate "Testcase for the NX non-executable stack feature"
125	depends on DEBUG_KERNEL && m
126	---help---
127	  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
131config DOUBLEFAULT
132	default y
133	bool "Enable doublefault exception handler" if EXPERT
134	---help---
135	  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
140config DEBUG_TLBFLUSH
141	bool "Set upper limit of TLB entries to flush one-by-one"
142	depends on DEBUG_KERNEL
143	---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
159config IOMMU_DEBUG
160	bool "Enable IOMMU debugging"
161	depends on GART_IOMMU && DEBUG_KERNEL
162	depends on X86_64
163	---help---
164	  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
172	  options. See Documentation/x86/x86_64/boot-options.txt for more
173	  details.
174
175config 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
183config IOMMU_LEAK
184	bool "IOMMU leak tracing"
185	depends on IOMMU_DEBUG && DMA_API_DEBUG
186	---help---
187	  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
190config HAVE_MMIOTRACE_SUPPORT
191	def_bool y
192
193config X86_DECODER_SELFTEST
194	bool "x86 instruction decoder selftest"
195	depends on DEBUG_KERNEL && KPROBES
196	depends on !COMPILE_TEST
197	---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
203#
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"
225	default IO_DELAY_0X80
226
227config IO_DELAY_0X80
228	bool "port 0x80 based port-IO delay [recommended]"
229	---help---
230	  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"
235	---help---
236	  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"
241	---help---
242	  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"
247	---help---
248	  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
276
277config DEBUG_BOOT_PARAMS
278	bool "Debug boot parameters"
279	depends on DEBUG_KERNEL
280	depends on DEBUG_FS
281	---help---
282	  This option will cause struct boot_params to be exported via debugfs.
283
284config CPA_DEBUG
285	bool "CPA self-test code"
286	depends on DEBUG_KERNEL
287	---help---
288	  Do change_page_attr() self-tests every 30 seconds.
289
290config OPTIMIZE_INLINING
291	bool "Allow gcc to uninline functions marked 'inline'"
292	---help---
293	  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
297	  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.
301
302	  If unsure, say N.
303
304config 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
316config DEBUG_NMI_SELFTEST
317	bool "NMI Selftest"
318	depends on DEBUG_KERNEL && X86_LOCAL_APIC
319	---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
328config 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
341config 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
353config 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
364endmenu
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

  1# SPDX-License-Identifier: GPL-2.0
  2
  3config TRACE_IRQFLAGS_SUPPORT
  4	def_bool y
  5
  6config EARLY_PRINTK_USB
  7	bool
  8
  9config X86_VERBOSE_BOOTUP
 10	bool "Enable verbose x86 bootup info messages"
 11	default y
 12	---help---
 13	  Enables the informational output from the decompression stage
 14	  (e.g. bzImage) of the boot. If you disable this you will still
 15	  see errors. Disable this if you want silent bootup.
 16
 17config EARLY_PRINTK
 18	bool "Early printk" if EXPERT
 19	default y
 20	---help---
 21	  Write kernel log output directly into the VGA buffer or to a serial
 22	  port.
 23
 24	  This is useful for kernel debugging when your machine crashes very
 25	  early before the console code is initialized. For normal operation
 26	  it is not recommended because it looks ugly and doesn't cooperate
 27	  with klogd/syslogd or the X server. You should normally say N here,
 28	  unless you want to debug such a crash.
 29
 30config EARLY_PRINTK_DBGP
 31	bool "Early printk via EHCI debug port"
 32	depends on EARLY_PRINTK && PCI
 33	select EARLY_PRINTK_USB
 34	---help---
 35	  Write kernel log output directly into the EHCI debug port.
 36
 37	  This is useful for kernel debugging when your machine crashes very
 38	  early before the console code is initialized. For normal operation
 39	  it is not recommended because it looks ugly and doesn't cooperate
 40	  with klogd/syslogd or the X server. You should normally say N here,
 41	  unless you want to debug such a crash. You need usb debug device.
 42
 43config EARLY_PRINTK_USB_XDBC
 44	bool "Early printk via the xHCI debug port"
 45	depends on EARLY_PRINTK && PCI
 46	select EARLY_PRINTK_USB
 47	---help---
 48	  Write kernel log output directly into the xHCI debug port.
 49
 50	  One use for this feature is kernel debugging, for example when your
 51	  machine crashes very early before the regular console code is
 52	  initialized. Other uses include simpler, lockless logging instead of
 53	  a full-blown printk console driver + klogd.
 54
 55	  For normal production environments this is normally not recommended,
 56	  because it doesn't feed events into klogd/syslogd and doesn't try to
 57	  print anything on the screen.
 58
 59	  You should normally say N here, unless you want to debug early
 60	  crashes or need a very simple printk logging facility.
 61
 62config MCSAFE_TEST
 63	def_bool n
 64
 65config X86_PTDUMP_CORE
 66	def_bool n
 67
 68config X86_PTDUMP
 69	tristate "Export kernel pagetable layout to userspace via debugfs"
 70	depends on DEBUG_KERNEL
 71	select DEBUG_FS
 72	select X86_PTDUMP_CORE
 73	---help---
 74	  Say Y here if you want to show the kernel pagetable layout in a
 75	  debugfs file. This information is only useful for kernel developers
 76	  who are working in architecture specific areas of the kernel.
 77	  It is probably not a good idea to enable this feature in a production
 78	  kernel.
 79	  If in doubt, say "N"
 80
 81config EFI_PGT_DUMP
 82	bool "Dump the EFI pagetable"
 83	depends on EFI
 84	select X86_PTDUMP_CORE
 85	---help---
 86	  Enable this if you want to dump the EFI page table before
 87	  enabling virtual mode. This can be used to debug miscellaneous
 88	  issues with the mapping of the EFI runtime regions into that
 89	  table.
 90
 
 
 
 
 
 
 
 
 91config DEBUG_WX
 92	bool "Warn on W+X mappings at boot"
 93	select X86_PTDUMP_CORE
 94	---help---
 95	  Generate a warning if any W+X mappings are found at boot.
 96
 97	  This is useful for discovering cases where the kernel is leaving
 98	  W+X mappings after applying NX, as such mappings are a security risk.
 99
100	  Look for a message in dmesg output like this:
101
102	    x86/mm: Checked W+X mappings: passed, no W+X pages found.
103
104	  or like this, if the check failed:
105
106	    x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found.
107
108	  Note that even if the check fails, your kernel is possibly
109	  still fine, as W+X mappings are not a security hole in
110	  themselves, what they do is that they make the exploitation
111	  of other unfixed kernel bugs easier.
112
113	  There is no runtime or memory usage effect of this option
114	  once the kernel has booted up - it's a one time check.
115
116	  If in doubt, say "Y".
117
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
118config DOUBLEFAULT
119	default y
120	bool "Enable doublefault exception handler" if EXPERT
121	---help---
122	  This option allows trapping of rare doublefault exceptions that
123	  would otherwise cause a system to silently reboot. Disabling this
124	  option saves about 4k and might cause you much additional grey
125	  hair.
126
127config DEBUG_TLBFLUSH
128	bool "Set upper limit of TLB entries to flush one-by-one"
129	depends on DEBUG_KERNEL
130	---help---
131
132	X86-only for now.
133
134	This option allows the user to tune the amount of TLB entries the
135	kernel flushes one-by-one instead of doing a full TLB flush. In
136	certain situations, the former is cheaper. This is controlled by the
137	tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
138	to -1, the code flushes the whole TLB unconditionally. Otherwise,
139	for positive values of it, the kernel will use single TLB entry
140	invalidating instructions according to the following formula:
141
142	flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
143
144	If in doubt, say "N".
145
146config IOMMU_DEBUG
147	bool "Enable IOMMU debugging"
148	depends on GART_IOMMU && DEBUG_KERNEL
149	depends on X86_64
150	---help---
151	  Force the IOMMU to on even when you have less than 4GB of
152	  memory and add debugging code. On overflow always panic. And
153	  allow to enable IOMMU leak tracing. Can be disabled at boot
154	  time with iommu=noforce. This will also enable scatter gather
155	  list merging.  Currently not recommended for production
156	  code. When you use it make sure you have a big enough
157	  IOMMU/AGP aperture.  Most of the options enabled by this can
158	  be set more finegrained using the iommu= command line
159	  options. See Documentation/x86/x86_64/boot-options.rst for more
160	  details.
161
 
 
 
 
 
 
 
 
162config IOMMU_LEAK
163	bool "IOMMU leak tracing"
164	depends on IOMMU_DEBUG && DMA_API_DEBUG
165	---help---
166	  Add a simple leak tracer to the IOMMU code. This is useful when you
167	  are debugging a buggy device driver that leaks IOMMU mappings.
168
169config HAVE_MMIOTRACE_SUPPORT
170	def_bool y
171
172config X86_DECODER_SELFTEST
173	bool "x86 instruction decoder selftest"
174	depends on DEBUG_KERNEL && INSTRUCTION_DECODER
175	depends on !COMPILE_TEST
176	---help---
177	 Perform x86 instruction decoder selftests at build time.
178	 This option is useful for checking the sanity of x86 instruction
179	 decoder code.
180	 If unsure, say "N".
181
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
182choice
183	prompt "IO delay type"
184	default IO_DELAY_0X80
185
186config IO_DELAY_0X80
187	bool "port 0x80 based port-IO delay [recommended]"
188	---help---
189	  This is the traditional Linux IO delay used for in/out_p.
190	  It is the most tested hence safest selection here.
191
192config IO_DELAY_0XED
193	bool "port 0xed based port-IO delay"
194	---help---
195	  Use port 0xed as the IO delay. This frees up port 0x80 which is
196	  often used as a hardware-debug port.
197
198config IO_DELAY_UDELAY
199	bool "udelay based port-IO delay"
200	---help---
201	  Use udelay(2) as the IO delay method. This provides the delay
202	  while not having any side-effect on the IO port space.
203
204config IO_DELAY_NONE
205	bool "no port-IO delay"
206	---help---
207	  No port-IO delay. Will break on old boxes that require port-IO
208	  delay for certain operations. Should work on most new machines.
209
210endchoice
211
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
212config DEBUG_BOOT_PARAMS
213	bool "Debug boot parameters"
214	depends on DEBUG_KERNEL
215	depends on DEBUG_FS
216	---help---
217	  This option will cause struct boot_params to be exported via debugfs.
218
219config CPA_DEBUG
220	bool "CPA self-test code"
221	depends on DEBUG_KERNEL
222	---help---
223	  Do change_page_attr() self-tests every 30 seconds.
224
 
 
 
 
 
 
 
 
 
 
 
 
 
 
225config DEBUG_ENTRY
226	bool "Debug low-level entry code"
227	depends on DEBUG_KERNEL
228	---help---
229	  This option enables sanity checks in x86's low-level entry code.
230	  Some of these sanity checks may slow down kernel entries and
231	  exits or otherwise impact performance.
232
 
 
233	  If unsure, say N.
234
235config DEBUG_NMI_SELFTEST
236	bool "NMI Selftest"
237	depends on DEBUG_KERNEL && X86_LOCAL_APIC
238	---help---
239	  Enabling this option turns on a quick NMI selftest to verify
240	  that the NMI behaves correctly.
241
242	  This might help diagnose strange hangs that rely on NMI to
243	  function properly.
244
245	  If unsure, say N.
246
247config DEBUG_IMR_SELFTEST
248	bool "Isolated Memory Region self test"
 
249	depends on INTEL_IMR
250	---help---
251	  This option enables automated sanity testing of the IMR code.
252	  Some simple tests are run to verify IMR bounds checking, alignment
253	  and overlapping. This option is really only useful if you are
254	  debugging an IMR memory map or are modifying the IMR code and want to
255	  test your changes.
256
257	  If unsure say N here.
258
259config X86_DEBUG_FPU
260	bool "Debug the x86 FPU code"
261	depends on DEBUG_KERNEL
262	default y
263	---help---
264	  If this option is enabled then there will be extra sanity
265	  checks and (boot time) debug printouts added to the kernel.
266	  This debugging adds some small amount of runtime overhead
267	  to the kernel.
268
269	  If unsure, say N.
270
271config PUNIT_ATOM_DEBUG
272	tristate "ATOM Punit debug driver"
273	depends on PCI
274	select DEBUG_FS
275	select IOSF_MBI
276	---help---
277	  This is a debug driver, which gets the power states
278	  of all Punit North Complex devices. The power states of
279	  each device is exposed as part of the debugfs interface.
280	  The current power state can be read from
281	  /sys/kernel/debug/punit_atom/dev_power_state
282
283choice
284	prompt "Choose kernel unwinder"
285	default UNWINDER_ORC if X86_64
286	default UNWINDER_FRAME_POINTER if X86_32
287	---help---
288	  This determines which method will be used for unwinding kernel stack
289	  traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack,
290	  livepatch, lockdep, and more.
291
292config UNWINDER_ORC
293	bool "ORC unwinder"
294	depends on X86_64
295	select STACK_VALIDATION
296	---help---
297	  This option enables the ORC (Oops Rewind Capability) unwinder for
298	  unwinding kernel stack traces.  It uses a custom data format which is
299	  a simplified version of the DWARF Call Frame Information standard.
300
301	  This unwinder is more accurate across interrupt entry frames than the
302	  frame pointer unwinder.  It also enables a 5-10% performance
303	  improvement across the entire kernel compared to frame pointers.
304
305	  Enabling this option will increase the kernel's runtime memory usage
306	  by roughly 2-4MB, depending on your kernel config.
307
308config UNWINDER_FRAME_POINTER
309	bool "Frame pointer unwinder"
310	select FRAME_POINTER
311	---help---
312	  This option enables the frame pointer unwinder for unwinding kernel
313	  stack traces.
314
315	  The unwinder itself is fast and it uses less RAM than the ORC
316	  unwinder, but the kernel text size will grow by ~3% and the kernel's
317	  overall performance will degrade by roughly 5-10%.
318
319	  This option is recommended if you want to use the livepatch
320	  consistency model, as this is currently the only way to get a
321	  reliable stack trace (CONFIG_HAVE_RELIABLE_STACKTRACE).
322
323config UNWINDER_GUESS
324	bool "Guess unwinder"
325	depends on EXPERT
326	depends on !STACKDEPOT
327	---help---
328	  This option enables the "guess" unwinder for unwinding kernel stack
329	  traces.  It scans the stack and reports every kernel text address it
330	  finds.  Some of the addresses it reports may be incorrect.
331
332	  While this option often produces false positives, it can still be
333	  useful in many cases.  Unlike the other unwinders, it has no runtime
334	  overhead.
335
336endchoice
337
338config FRAME_POINTER
339	depends on !UNWINDER_ORC && !UNWINDER_GUESS
340	bool