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

  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