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b2441318 | 1 | # SPDX-License-Identifier: GPL-2.0 |
1da177e4 | 2 | |
55f327fa | 3 | config TRACE_IRQFLAGS_SUPPORT |
d013a27c | 4 | def_bool y |
55f327fa | 5 | |
aeb9dd1d LB |
6 | config EARLY_PRINTK_USB |
7 | bool | |
8 | ||
6bcb13b3 BC |
9 | config X86_VERBOSE_BOOTUP |
10 | bool "Enable verbose x86 bootup info messages" | |
11 | default y | |
8f9ca475 | 12 | ---help--- |
6bcb13b3 BC |
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 | ||
1da177e4 | 17 | config EARLY_PRINTK |
6a108a14 | 18 | bool "Early printk" if EXPERT |
1da177e4 | 19 | default y |
8f9ca475 | 20 | ---help--- |
1da177e4 LT |
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 | |
aeb9dd1d | 27 | with klogd/syslogd or the X server. You should normally say N here, |
1da177e4 LT |
28 | unless you want to debug such a crash. |
29 | ||
5c05917e YL |
30 | config EARLY_PRINTK_DBGP |
31 | bool "Early printk via EHCI debug port" | |
9749986a | 32 | depends on EARLY_PRINTK && PCI |
aeb9dd1d | 33 | select EARLY_PRINTK_USB |
8f9ca475 | 34 | ---help--- |
5c05917e YL |
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 | |
aeb9dd1d | 40 | with klogd/syslogd or the X server. You should normally say N here, |
5c05917e YL |
41 | unless you want to debug such a crash. You need usb debug device. |
42 | ||
aeb9dd1d LB |
43 | config 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 | ||
5d8beee2 DW |
62 | config MCSAFE_TEST |
63 | def_bool n | |
64 | ||
e1a58320 SS |
65 | config X86_PTDUMP_CORE |
66 | def_bool n | |
67 | ||
926e5392 | 68 | config X86_PTDUMP |
8609d1b5 | 69 | tristate "Export kernel pagetable layout to userspace via debugfs" |
fe770bf0 | 70 | depends on DEBUG_KERNEL |
926e5392 | 71 | select DEBUG_FS |
e1a58320 | 72 | select X86_PTDUMP_CORE |
8f9ca475 | 73 | ---help--- |
926e5392 AV |
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 | ||
11cc8512 BP |
81 | config EFI_PGT_DUMP |
82 | bool "Dump the EFI pagetable" | |
e1a58320 SS |
83 | depends on EFI |
84 | select X86_PTDUMP_CORE | |
11cc8512 BP |
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 | ||
e1a58320 SS |
91 | config DEBUG_WX |
92 | bool "Warn on W+X mappings at boot" | |
e1a58320 SS |
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 | ||
102e41fd AK |
118 | config DOUBLEFAULT |
119 | default y | |
6a108a14 | 120 | bool "Enable doublefault exception handler" if EXPERT |
8f9ca475 | 121 | ---help--- |
d013a27c RD |
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 | ||
3df3212f AS |
127 | config DEBUG_TLBFLUSH |
128 | bool "Set upper limit of TLB entries to flush one-by-one" | |
cd69aa6b | 129 | depends on DEBUG_KERNEL |
3df3212f AS |
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 | ||
d013a27c RD |
146 | config IOMMU_DEBUG |
147 | bool "Enable IOMMU debugging" | |
966396d3 | 148 | depends on GART_IOMMU && DEBUG_KERNEL |
d013a27c | 149 | depends on X86_64 |
8f9ca475 | 150 | ---help--- |
d013a27c RD |
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 | |
cb1aaebe | 159 | options. See Documentation/x86/x86_64/boot-options.rst for more |
d013a27c RD |
160 | details. |
161 | ||
162 | config IOMMU_LEAK | |
163 | bool "IOMMU leak tracing" | |
19c1a6f5 | 164 | depends on IOMMU_DEBUG && DMA_API_DEBUG |
8f9ca475 | 165 | ---help--- |
d013a27c RD |
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 | ||
6bc5c366 PP |
169 | config HAVE_MMIOTRACE_SUPPORT |
170 | def_bool y | |
8b7d89d0 | 171 | |
ca0e9bad | 172 | config X86_DECODER_SELFTEST |
cbe5c34c | 173 | bool "x86 instruction decoder selftest" |
7720804a | 174 | depends on DEBUG_KERNEL && INSTRUCTION_DECODER |
f8f20234 | 175 | depends on !COMPILE_TEST |
ca0e9bad MH |
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 | ||
6e7c4025 IM |
182 | choice |
183 | prompt "IO delay type" | |
fd59e9e9 | 184 | default IO_DELAY_0X80 |
6e7c4025 IM |
185 | |
186 | config IO_DELAY_0X80 | |
187 | bool "port 0x80 based port-IO delay [recommended]" | |
8f9ca475 | 188 | ---help--- |
6e7c4025 IM |
189 | This is the traditional Linux IO delay used for in/out_p. |
190 | It is the most tested hence safest selection here. | |
191 | ||
192 | config IO_DELAY_0XED | |
193 | bool "port 0xed based port-IO delay" | |
8f9ca475 | 194 | ---help--- |
6e7c4025 IM |
195 | Use port 0xed as the IO delay. This frees up port 0x80 which is |
196 | often used as a hardware-debug port. | |
197 | ||
198 | config IO_DELAY_UDELAY | |
199 | bool "udelay based port-IO delay" | |
8f9ca475 | 200 | ---help--- |
6e7c4025 IM |
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 | ||
204 | config IO_DELAY_NONE | |
205 | bool "no port-IO delay" | |
8f9ca475 | 206 | ---help--- |
6e7c4025 IM |
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 | ||
210 | endchoice | |
211 | ||
6d7d7433 HY |
212 | config DEBUG_BOOT_PARAMS |
213 | bool "Debug boot parameters" | |
214 | depends on DEBUG_KERNEL | |
215 | depends on DEBUG_FS | |
8f9ca475 | 216 | ---help--- |
6d7d7433 HY |
217 | This option will cause struct boot_params to be exported via debugfs. |
218 | ||
0c42f392 | 219 | config CPA_DEBUG |
971a52d6 | 220 | bool "CPA self-test code" |
f316fe68 | 221 | depends on DEBUG_KERNEL |
8f9ca475 | 222 | ---help--- |
971a52d6 | 223 | Do change_page_attr() self-tests every 30 seconds. |
0c42f392 | 224 | |
a97439aa AL |
225 | config 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 | ||
a97439aa AL |
233 | If unsure, say N. |
234 | ||
99e8b9ca DZ |
235 | config DEBUG_NMI_SELFTEST |
236 | bool "NMI Selftest" | |
4f941c57 | 237 | depends on DEBUG_KERNEL && X86_LOCAL_APIC |
99e8b9ca DZ |
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 | ||
28a375df BD |
247 | config DEBUG_IMR_SELFTEST |
248 | bool "Isolated Memory Region self test" | |
28a375df BD |
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 | ||
e97131a8 IM |
259 | config 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 | ||
956079e0 SP |
271 | config PUNIT_ATOM_DEBUG |
272 | tristate "ATOM Punit debug driver" | |
d689c64d | 273 | depends on PCI |
956079e0 SP |
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 | ||
81d38719 JP |
283 | choice |
284 | prompt "Choose kernel unwinder" | |
fc72ae40 JP |
285 | default UNWINDER_ORC if X86_64 |
286 | default UNWINDER_FRAME_POINTER if X86_32 | |
81d38719 JP |
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 | ||
11af8474 | 292 | config UNWINDER_ORC |
ee9f8fce | 293 | bool "ORC unwinder" |
81d38719 | 294 | depends on X86_64 |
ee9f8fce JP |
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 | |
a34a766f JP |
302 | frame pointer unwinder. It also enables a 5-10% performance |
303 | improvement across the entire kernel compared to frame pointers. | |
ee9f8fce JP |
304 | |
305 | Enabling this option will increase the kernel's runtime memory usage | |
306 | by roughly 2-4MB, depending on your kernel config. | |
307 | ||
fc72ae40 JP |
308 | config 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 | ||
11af8474 | 323 | config UNWINDER_GUESS |
81d38719 JP |
324 | bool "Guess unwinder" |
325 | depends on EXPERT | |
0a373d4f | 326 | depends on !STACKDEPOT |
81d38719 JP |
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 | ||
336 | endchoice | |
337 | ||
338 | config FRAME_POINTER | |
11af8474 | 339 | depends on !UNWINDER_ORC && !UNWINDER_GUESS |
81d38719 | 340 | bool |