Commit | Line | Data |
---|---|---|
b2441318 | 1 | # SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | menu "Kernel hacking" |
3 | ||
55f327fa | 4 | config TRACE_IRQFLAGS_SUPPORT |
d013a27c | 5 | def_bool y |
55f327fa | 6 | |
1da177e4 LT |
7 | source "lib/Kconfig.debug" |
8 | ||
aeb9dd1d LB |
9 | config EARLY_PRINTK_USB |
10 | bool | |
11 | ||
6bcb13b3 BC |
12 | config X86_VERBOSE_BOOTUP |
13 | bool "Enable verbose x86 bootup info messages" | |
14 | default y | |
8f9ca475 | 15 | ---help--- |
6bcb13b3 BC |
16 | Enables the informational output from the decompression stage |
17 | (e.g. bzImage) of the boot. If you disable this you will still | |
18 | see errors. Disable this if you want silent bootup. | |
19 | ||
1da177e4 | 20 | config EARLY_PRINTK |
6a108a14 | 21 | bool "Early printk" if EXPERT |
1da177e4 | 22 | default y |
8f9ca475 | 23 | ---help--- |
1da177e4 LT |
24 | Write kernel log output directly into the VGA buffer or to a serial |
25 | port. | |
26 | ||
27 | This is useful for kernel debugging when your machine crashes very | |
28 | early before the console code is initialized. For normal operation | |
29 | it is not recommended because it looks ugly and doesn't cooperate | |
aeb9dd1d | 30 | with klogd/syslogd or the X server. You should normally say N here, |
1da177e4 LT |
31 | unless you want to debug such a crash. |
32 | ||
5c05917e YL |
33 | config EARLY_PRINTK_DBGP |
34 | bool "Early printk via EHCI debug port" | |
9749986a | 35 | depends on EARLY_PRINTK && PCI |
aeb9dd1d | 36 | select EARLY_PRINTK_USB |
8f9ca475 | 37 | ---help--- |
5c05917e YL |
38 | Write kernel log output directly into the EHCI debug port. |
39 | ||
40 | This is useful for kernel debugging when your machine crashes very | |
41 | early before the console code is initialized. For normal operation | |
42 | it is not recommended because it looks ugly and doesn't cooperate | |
aeb9dd1d | 43 | with klogd/syslogd or the X server. You should normally say N here, |
5c05917e YL |
44 | unless you want to debug such a crash. You need usb debug device. |
45 | ||
72548e83 MF |
46 | config EARLY_PRINTK_EFI |
47 | bool "Early printk via the EFI framebuffer" | |
48 | depends on EFI && EARLY_PRINTK | |
49 | select FONT_SUPPORT | |
50 | ---help--- | |
51 | Write kernel log output directly into the EFI framebuffer. | |
52 | ||
53 | This is useful for kernel debugging when your machine crashes very | |
54 | early before the console code is initialized. | |
55 | ||
aeb9dd1d LB |
56 | config EARLY_PRINTK_USB_XDBC |
57 | bool "Early printk via the xHCI debug port" | |
58 | depends on EARLY_PRINTK && PCI | |
59 | select EARLY_PRINTK_USB | |
60 | ---help--- | |
61 | Write kernel log output directly into the xHCI debug port. | |
62 | ||
63 | One use for this feature is kernel debugging, for example when your | |
64 | machine crashes very early before the regular console code is | |
65 | initialized. Other uses include simpler, lockless logging instead of | |
66 | a full-blown printk console driver + klogd. | |
67 | ||
68 | For normal production environments this is normally not recommended, | |
69 | because it doesn't feed events into klogd/syslogd and doesn't try to | |
70 | print anything on the screen. | |
71 | ||
72 | You should normally say N here, unless you want to debug early | |
73 | crashes or need a very simple printk logging facility. | |
74 | ||
5d8beee2 DW |
75 | config MCSAFE_TEST |
76 | def_bool n | |
77 | ||
e1a58320 SS |
78 | config X86_PTDUMP_CORE |
79 | def_bool n | |
80 | ||
926e5392 | 81 | config X86_PTDUMP |
8609d1b5 | 82 | tristate "Export kernel pagetable layout to userspace via debugfs" |
fe770bf0 | 83 | depends on DEBUG_KERNEL |
926e5392 | 84 | select DEBUG_FS |
e1a58320 | 85 | select X86_PTDUMP_CORE |
8f9ca475 | 86 | ---help--- |
926e5392 AV |
87 | Say Y here if you want to show the kernel pagetable layout in a |
88 | debugfs file. This information is only useful for kernel developers | |
89 | who are working in architecture specific areas of the kernel. | |
90 | It is probably not a good idea to enable this feature in a production | |
91 | kernel. | |
92 | If in doubt, say "N" | |
93 | ||
11cc8512 BP |
94 | config EFI_PGT_DUMP |
95 | bool "Dump the EFI pagetable" | |
e1a58320 SS |
96 | depends on EFI |
97 | select X86_PTDUMP_CORE | |
11cc8512 BP |
98 | ---help--- |
99 | Enable this if you want to dump the EFI page table before | |
100 | enabling virtual mode. This can be used to debug miscellaneous | |
101 | issues with the mapping of the EFI runtime regions into that | |
102 | table. | |
103 | ||
e1a58320 SS |
104 | config DEBUG_WX |
105 | bool "Warn on W+X mappings at boot" | |
e1a58320 SS |
106 | select X86_PTDUMP_CORE |
107 | ---help--- | |
108 | Generate a warning if any W+X mappings are found at boot. | |
109 | ||
110 | This is useful for discovering cases where the kernel is leaving | |
111 | W+X mappings after applying NX, as such mappings are a security risk. | |
112 | ||
113 | Look for a message in dmesg output like this: | |
114 | ||
115 | x86/mm: Checked W+X mappings: passed, no W+X pages found. | |
116 | ||
117 | or like this, if the check failed: | |
118 | ||
119 | x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found. | |
120 | ||
121 | Note that even if the check fails, your kernel is possibly | |
122 | still fine, as W+X mappings are not a security hole in | |
123 | themselves, what they do is that they make the exploitation | |
124 | of other unfixed kernel bugs easier. | |
125 | ||
126 | There is no runtime or memory usage effect of this option | |
127 | once the kernel has booted up - it's a one time check. | |
128 | ||
129 | If in doubt, say "Y". | |
130 | ||
102e41fd AK |
131 | config DOUBLEFAULT |
132 | default y | |
6a108a14 | 133 | bool "Enable doublefault exception handler" if EXPERT |
8f9ca475 | 134 | ---help--- |
d013a27c RD |
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 | ||
3df3212f AS |
140 | config DEBUG_TLBFLUSH |
141 | bool "Set upper limit of TLB entries to flush one-by-one" | |
cd69aa6b | 142 | depends on DEBUG_KERNEL |
3df3212f AS |
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 | ||
d013a27c RD |
159 | config IOMMU_DEBUG |
160 | bool "Enable IOMMU debugging" | |
966396d3 | 161 | depends on GART_IOMMU && DEBUG_KERNEL |
d013a27c | 162 | depends on X86_64 |
8f9ca475 | 163 | ---help--- |
d013a27c RD |
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 | |
395cf969 | 172 | options. See Documentation/x86/x86_64/boot-options.txt for more |
d013a27c RD |
173 | details. |
174 | ||
175 | config IOMMU_LEAK | |
176 | bool "IOMMU leak tracing" | |
19c1a6f5 | 177 | depends on IOMMU_DEBUG && DMA_API_DEBUG |
8f9ca475 | 178 | ---help--- |
d013a27c RD |
179 | Add a simple leak tracer to the IOMMU code. This is useful when you |
180 | are debugging a buggy device driver that leaks IOMMU mappings. | |
181 | ||
6bc5c366 PP |
182 | config HAVE_MMIOTRACE_SUPPORT |
183 | def_bool y | |
8b7d89d0 | 184 | |
ca0e9bad | 185 | config X86_DECODER_SELFTEST |
cbe5c34c OH |
186 | bool "x86 instruction decoder selftest" |
187 | depends on DEBUG_KERNEL && KPROBES | |
f8f20234 | 188 | depends on !COMPILE_TEST |
ca0e9bad MH |
189 | ---help--- |
190 | Perform x86 instruction decoder selftests at build time. | |
191 | This option is useful for checking the sanity of x86 instruction | |
192 | decoder code. | |
193 | If unsure, say "N". | |
194 | ||
6e7c4025 IM |
195 | # |
196 | # IO delay types: | |
197 | # | |
198 | ||
199 | config IO_DELAY_TYPE_0X80 | |
200 | int | |
201 | default "0" | |
202 | ||
203 | config IO_DELAY_TYPE_0XED | |
204 | int | |
205 | default "1" | |
206 | ||
207 | config IO_DELAY_TYPE_UDELAY | |
208 | int | |
209 | default "2" | |
210 | ||
211 | config IO_DELAY_TYPE_NONE | |
212 | int | |
213 | default "3" | |
214 | ||
215 | choice | |
216 | prompt "IO delay type" | |
fd59e9e9 | 217 | default IO_DELAY_0X80 |
6e7c4025 IM |
218 | |
219 | config IO_DELAY_0X80 | |
220 | bool "port 0x80 based port-IO delay [recommended]" | |
8f9ca475 | 221 | ---help--- |
6e7c4025 IM |
222 | This is the traditional Linux IO delay used for in/out_p. |
223 | It is the most tested hence safest selection here. | |
224 | ||
225 | config IO_DELAY_0XED | |
226 | bool "port 0xed based port-IO delay" | |
8f9ca475 | 227 | ---help--- |
6e7c4025 IM |
228 | Use port 0xed as the IO delay. This frees up port 0x80 which is |
229 | often used as a hardware-debug port. | |
230 | ||
231 | config IO_DELAY_UDELAY | |
232 | bool "udelay based port-IO delay" | |
8f9ca475 | 233 | ---help--- |
6e7c4025 IM |
234 | Use udelay(2) as the IO delay method. This provides the delay |
235 | while not having any side-effect on the IO port space. | |
236 | ||
237 | config IO_DELAY_NONE | |
238 | bool "no port-IO delay" | |
8f9ca475 | 239 | ---help--- |
6e7c4025 IM |
240 | No port-IO delay. Will break on old boxes that require port-IO |
241 | delay for certain operations. Should work on most new machines. | |
242 | ||
243 | endchoice | |
244 | ||
245 | if IO_DELAY_0X80 | |
246 | config DEFAULT_IO_DELAY_TYPE | |
247 | int | |
248 | default IO_DELAY_TYPE_0X80 | |
249 | endif | |
250 | ||
251 | if IO_DELAY_0XED | |
252 | config DEFAULT_IO_DELAY_TYPE | |
253 | int | |
254 | default IO_DELAY_TYPE_0XED | |
255 | endif | |
256 | ||
257 | if IO_DELAY_UDELAY | |
258 | config DEFAULT_IO_DELAY_TYPE | |
259 | int | |
260 | default IO_DELAY_TYPE_UDELAY | |
261 | endif | |
262 | ||
263 | if IO_DELAY_NONE | |
264 | config DEFAULT_IO_DELAY_TYPE | |
265 | int | |
266 | default IO_DELAY_TYPE_NONE | |
267 | endif | |
b02aae9c | 268 | |
6d7d7433 HY |
269 | config DEBUG_BOOT_PARAMS |
270 | bool "Debug boot parameters" | |
271 | depends on DEBUG_KERNEL | |
272 | depends on DEBUG_FS | |
8f9ca475 | 273 | ---help--- |
6d7d7433 HY |
274 | This option will cause struct boot_params to be exported via debugfs. |
275 | ||
0c42f392 | 276 | config CPA_DEBUG |
971a52d6 | 277 | bool "CPA self-test code" |
f316fe68 | 278 | depends on DEBUG_KERNEL |
8f9ca475 | 279 | ---help--- |
971a52d6 | 280 | Do change_page_attr() self-tests every 30 seconds. |
0c42f392 | 281 | |
60a3cdd0 IM |
282 | config OPTIMIZE_INLINING |
283 | bool "Allow gcc to uninline functions marked 'inline'" | |
8f9ca475 | 284 | ---help--- |
60a3cdd0 IM |
285 | This option determines if the kernel forces gcc to inline the functions |
286 | developers have marked 'inline'. Doing so takes away freedom from gcc to | |
287 | do what it thinks is best, which is desirable for the gcc 3.x series of | |
288 | compilers. The gcc 4.x series have a rewritten inlining algorithm and | |
63fb7085 SW |
289 | enabling this option will generate a smaller kernel there. Hopefully |
290 | this algorithm is so good that allowing gcc 4.x and above to make the | |
291 | decision will become the default in the future. Until then this option | |
292 | is there to test gcc for this. | |
c9af1e33 | 293 | |
3f9b5cc0 IM |
294 | If unsure, say N. |
295 | ||
a97439aa AL |
296 | config DEBUG_ENTRY |
297 | bool "Debug low-level entry code" | |
298 | depends on DEBUG_KERNEL | |
299 | ---help--- | |
300 | This option enables sanity checks in x86's low-level entry code. | |
301 | Some of these sanity checks may slow down kernel entries and | |
302 | exits or otherwise impact performance. | |
303 | ||
a97439aa AL |
304 | If unsure, say N. |
305 | ||
99e8b9ca DZ |
306 | config DEBUG_NMI_SELFTEST |
307 | bool "NMI Selftest" | |
4f941c57 | 308 | depends on DEBUG_KERNEL && X86_LOCAL_APIC |
99e8b9ca DZ |
309 | ---help--- |
310 | Enabling this option turns on a quick NMI selftest to verify | |
311 | that the NMI behaves correctly. | |
312 | ||
313 | This might help diagnose strange hangs that rely on NMI to | |
314 | function properly. | |
315 | ||
316 | If unsure, say N. | |
317 | ||
28a375df BD |
318 | config DEBUG_IMR_SELFTEST |
319 | bool "Isolated Memory Region self test" | |
320 | default n | |
321 | depends on INTEL_IMR | |
322 | ---help--- | |
323 | This option enables automated sanity testing of the IMR code. | |
324 | Some simple tests are run to verify IMR bounds checking, alignment | |
325 | and overlapping. This option is really only useful if you are | |
326 | debugging an IMR memory map or are modifying the IMR code and want to | |
327 | test your changes. | |
328 | ||
329 | If unsure say N here. | |
330 | ||
e97131a8 IM |
331 | config X86_DEBUG_FPU |
332 | bool "Debug the x86 FPU code" | |
333 | depends on DEBUG_KERNEL | |
334 | default y | |
335 | ---help--- | |
336 | If this option is enabled then there will be extra sanity | |
337 | checks and (boot time) debug printouts added to the kernel. | |
338 | This debugging adds some small amount of runtime overhead | |
339 | to the kernel. | |
340 | ||
341 | If unsure, say N. | |
342 | ||
956079e0 SP |
343 | config PUNIT_ATOM_DEBUG |
344 | tristate "ATOM Punit debug driver" | |
d689c64d | 345 | depends on PCI |
956079e0 SP |
346 | select DEBUG_FS |
347 | select IOSF_MBI | |
348 | ---help--- | |
349 | This is a debug driver, which gets the power states | |
350 | of all Punit North Complex devices. The power states of | |
351 | each device is exposed as part of the debugfs interface. | |
352 | The current power state can be read from | |
353 | /sys/kernel/debug/punit_atom/dev_power_state | |
354 | ||
81d38719 JP |
355 | choice |
356 | prompt "Choose kernel unwinder" | |
fc72ae40 JP |
357 | default UNWINDER_ORC if X86_64 |
358 | default UNWINDER_FRAME_POINTER if X86_32 | |
81d38719 JP |
359 | ---help--- |
360 | This determines which method will be used for unwinding kernel stack | |
361 | traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack, | |
362 | livepatch, lockdep, and more. | |
363 | ||
11af8474 | 364 | config UNWINDER_ORC |
ee9f8fce | 365 | bool "ORC unwinder" |
81d38719 | 366 | depends on X86_64 |
ee9f8fce JP |
367 | select STACK_VALIDATION |
368 | ---help--- | |
369 | This option enables the ORC (Oops Rewind Capability) unwinder for | |
370 | unwinding kernel stack traces. It uses a custom data format which is | |
371 | a simplified version of the DWARF Call Frame Information standard. | |
372 | ||
373 | This unwinder is more accurate across interrupt entry frames than the | |
a34a766f JP |
374 | frame pointer unwinder. It also enables a 5-10% performance |
375 | improvement across the entire kernel compared to frame pointers. | |
ee9f8fce JP |
376 | |
377 | Enabling this option will increase the kernel's runtime memory usage | |
378 | by roughly 2-4MB, depending on your kernel config. | |
379 | ||
fc72ae40 JP |
380 | config UNWINDER_FRAME_POINTER |
381 | bool "Frame pointer unwinder" | |
382 | select FRAME_POINTER | |
383 | ---help--- | |
384 | This option enables the frame pointer unwinder for unwinding kernel | |
385 | stack traces. | |
386 | ||
387 | The unwinder itself is fast and it uses less RAM than the ORC | |
388 | unwinder, but the kernel text size will grow by ~3% and the kernel's | |
389 | overall performance will degrade by roughly 5-10%. | |
390 | ||
391 | This option is recommended if you want to use the livepatch | |
392 | consistency model, as this is currently the only way to get a | |
393 | reliable stack trace (CONFIG_HAVE_RELIABLE_STACKTRACE). | |
394 | ||
11af8474 | 395 | config UNWINDER_GUESS |
81d38719 JP |
396 | bool "Guess unwinder" |
397 | depends on EXPERT | |
0a373d4f | 398 | depends on !STACKDEPOT |
81d38719 JP |
399 | ---help--- |
400 | This option enables the "guess" unwinder for unwinding kernel stack | |
401 | traces. It scans the stack and reports every kernel text address it | |
402 | finds. Some of the addresses it reports may be incorrect. | |
403 | ||
404 | While this option often produces false positives, it can still be | |
405 | useful in many cases. Unlike the other unwinders, it has no runtime | |
406 | overhead. | |
407 | ||
408 | endchoice | |
409 | ||
410 | config FRAME_POINTER | |
11af8474 | 411 | depends on !UNWINDER_ORC && !UNWINDER_GUESS |
81d38719 | 412 | bool |
ee9f8fce | 413 | |
c9af1e33 | 414 | endmenu |