Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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 EFI_PGT_DUMP
66 bool "Dump the EFI pagetable"
67 depends on EFI
68 select PTDUMP_CORE
69 ---help---
70 Enable this if you want to dump the EFI page table before
71 enabling virtual mode. This can be used to debug miscellaneous
72 issues with the mapping of the EFI runtime regions into that
73 table.
74
75config DEBUG_WX
76 bool "Warn on W+X mappings at boot"
77 select PTDUMP_CORE
78 ---help---
79 Generate a warning if any W+X mappings are found at boot.
80
81 This is useful for discovering cases where the kernel is leaving
82 W+X mappings after applying NX, as such mappings are a security risk.
83
84 Look for a message in dmesg output like this:
85
86 x86/mm: Checked W+X mappings: passed, no W+X pages found.
87
88 or like this, if the check failed:
89
90 x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found.
91
92 Note that even if the check fails, your kernel is possibly
93 still fine, as W+X mappings are not a security hole in
94 themselves, what they do is that they make the exploitation
95 of other unfixed kernel bugs easier.
96
97 There is no runtime or memory usage effect of this option
98 once the kernel has booted up - it's a one time check.
99
100 If in doubt, say "Y".
101
102config DOUBLEFAULT
103 default y
104 bool "Enable doublefault exception handler" if EXPERT && X86_32
105 ---help---
106 This option allows trapping of rare doublefault exceptions that
107 would otherwise cause a system to silently reboot. Disabling this
108 option saves about 4k and might cause you much additional grey
109 hair.
110
111config DEBUG_TLBFLUSH
112 bool "Set upper limit of TLB entries to flush one-by-one"
113 depends on DEBUG_KERNEL
114 ---help---
115
116 X86-only for now.
117
118 This option allows the user to tune the amount of TLB entries the
119 kernel flushes one-by-one instead of doing a full TLB flush. In
120 certain situations, the former is cheaper. This is controlled by the
121 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
122 to -1, the code flushes the whole TLB unconditionally. Otherwise,
123 for positive values of it, the kernel will use single TLB entry
124 invalidating instructions according to the following formula:
125
126 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
127
128 If in doubt, say "N".
129
130config IOMMU_DEBUG
131 bool "Enable IOMMU debugging"
132 depends on GART_IOMMU && DEBUG_KERNEL
133 depends on X86_64
134 ---help---
135 Force the IOMMU to on even when you have less than 4GB of
136 memory and add debugging code. On overflow always panic. And
137 allow to enable IOMMU leak tracing. Can be disabled at boot
138 time with iommu=noforce. This will also enable scatter gather
139 list merging. Currently not recommended for production
140 code. When you use it make sure you have a big enough
141 IOMMU/AGP aperture. Most of the options enabled by this can
142 be set more finegrained using the iommu= command line
143 options. See Documentation/x86/x86_64/boot-options.rst for more
144 details.
145
146config IOMMU_LEAK
147 bool "IOMMU leak tracing"
148 depends on IOMMU_DEBUG && DMA_API_DEBUG
149 ---help---
150 Add a simple leak tracer to the IOMMU code. This is useful when you
151 are debugging a buggy device driver that leaks IOMMU mappings.
152
153config HAVE_MMIOTRACE_SUPPORT
154 def_bool y
155
156config X86_DECODER_SELFTEST
157 bool "x86 instruction decoder selftest"
158 depends on DEBUG_KERNEL && INSTRUCTION_DECODER
159 depends on !COMPILE_TEST
160 ---help---
161 Perform x86 instruction decoder selftests at build time.
162 This option is useful for checking the sanity of x86 instruction
163 decoder code.
164 If unsure, say "N".
165
166choice
167 prompt "IO delay type"
168 default IO_DELAY_0X80
169
170config IO_DELAY_0X80
171 bool "port 0x80 based port-IO delay [recommended]"
172 ---help---
173 This is the traditional Linux IO delay used for in/out_p.
174 It is the most tested hence safest selection here.
175
176config IO_DELAY_0XED
177 bool "port 0xed based port-IO delay"
178 ---help---
179 Use port 0xed as the IO delay. This frees up port 0x80 which is
180 often used as a hardware-debug port.
181
182config IO_DELAY_UDELAY
183 bool "udelay based port-IO delay"
184 ---help---
185 Use udelay(2) as the IO delay method. This provides the delay
186 while not having any side-effect on the IO port space.
187
188config IO_DELAY_NONE
189 bool "no port-IO delay"
190 ---help---
191 No port-IO delay. Will break on old boxes that require port-IO
192 delay for certain operations. Should work on most new machines.
193
194endchoice
195
196config DEBUG_BOOT_PARAMS
197 bool "Debug boot parameters"
198 depends on DEBUG_KERNEL
199 depends on DEBUG_FS
200 ---help---
201 This option will cause struct boot_params to be exported via debugfs.
202
203config CPA_DEBUG
204 bool "CPA self-test code"
205 depends on DEBUG_KERNEL
206 ---help---
207 Do change_page_attr() self-tests every 30 seconds.
208
209config DEBUG_ENTRY
210 bool "Debug low-level entry code"
211 depends on DEBUG_KERNEL
212 ---help---
213 This option enables sanity checks in x86's low-level entry code.
214 Some of these sanity checks may slow down kernel entries and
215 exits or otherwise impact performance.
216
217 If unsure, say N.
218
219config DEBUG_NMI_SELFTEST
220 bool "NMI Selftest"
221 depends on DEBUG_KERNEL && X86_LOCAL_APIC
222 ---help---
223 Enabling this option turns on a quick NMI selftest to verify
224 that the NMI behaves correctly.
225
226 This might help diagnose strange hangs that rely on NMI to
227 function properly.
228
229 If unsure, say N.
230
231config DEBUG_IMR_SELFTEST
232 bool "Isolated Memory Region self test"
233 depends on INTEL_IMR
234 ---help---
235 This option enables automated sanity testing of the IMR code.
236 Some simple tests are run to verify IMR bounds checking, alignment
237 and overlapping. This option is really only useful if you are
238 debugging an IMR memory map or are modifying the IMR code and want to
239 test your changes.
240
241 If unsure say N here.
242
243config X86_DEBUG_FPU
244 bool "Debug the x86 FPU code"
245 depends on DEBUG_KERNEL
246 default y
247 ---help---
248 If this option is enabled then there will be extra sanity
249 checks and (boot time) debug printouts added to the kernel.
250 This debugging adds some small amount of runtime overhead
251 to the kernel.
252
253 If unsure, say N.
254
255config PUNIT_ATOM_DEBUG
256 tristate "ATOM Punit debug driver"
257 depends on PCI
258 select DEBUG_FS
259 select IOSF_MBI
260 ---help---
261 This is a debug driver, which gets the power states
262 of all Punit North Complex devices. The power states of
263 each device is exposed as part of the debugfs interface.
264 The current power state can be read from
265 /sys/kernel/debug/punit_atom/dev_power_state
266
267choice
268 prompt "Choose kernel unwinder"
269 default UNWINDER_ORC if X86_64
270 default UNWINDER_FRAME_POINTER if X86_32
271 ---help---
272 This determines which method will be used for unwinding kernel stack
273 traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack,
274 livepatch, lockdep, and more.
275
276config UNWINDER_ORC
277 bool "ORC unwinder"
278 depends on X86_64
279 select STACK_VALIDATION
280 ---help---
281 This option enables the ORC (Oops Rewind Capability) unwinder for
282 unwinding kernel stack traces. It uses a custom data format which is
283 a simplified version of the DWARF Call Frame Information standard.
284
285 This unwinder is more accurate across interrupt entry frames than the
286 frame pointer unwinder. It also enables a 5-10% performance
287 improvement across the entire kernel compared to frame pointers.
288
289 Enabling this option will increase the kernel's runtime memory usage
290 by roughly 2-4MB, depending on your kernel config.
291
292config UNWINDER_FRAME_POINTER
293 bool "Frame pointer unwinder"
294 select FRAME_POINTER
295 ---help---
296 This option enables the frame pointer unwinder for unwinding kernel
297 stack traces.
298
299 The unwinder itself is fast and it uses less RAM than the ORC
300 unwinder, but the kernel text size will grow by ~3% and the kernel's
301 overall performance will degrade by roughly 5-10%.
302
303config UNWINDER_GUESS
304 bool "Guess unwinder"
305 depends on EXPERT
306 depends on !STACKDEPOT
307 ---help---
308 This option enables the "guess" unwinder for unwinding kernel stack
309 traces. It scans the stack and reports every kernel text address it
310 finds. Some of the addresses it reports may be incorrect.
311
312 While this option often produces false positives, it can still be
313 useful in many cases. Unlike the other unwinders, it has no runtime
314 overhead.
315
316endchoice
317
318config FRAME_POINTER
319 depends on !UNWINDER_ORC && !UNWINDER_GUESS
320 bool