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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
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