1# SPDX-License-Identifier: GPL-2.0
2
3config TRACE_IRQFLAGS_NMI_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 EFI_PGT_DUMP
63	bool "Dump the EFI pagetable"
64	depends on EFI
65	select PTDUMP_CORE
66	help
67	  Enable this if you want to dump the EFI page table before
68	  enabling virtual mode. This can be used to debug miscellaneous
69	  issues with the mapping of the EFI runtime regions into that
70	  table.
71
72config DEBUG_TLBFLUSH
73	bool "Set upper limit of TLB entries to flush one-by-one"
74	depends on DEBUG_KERNEL
75	help
76
77	X86-only for now.
78
79	This option allows the user to tune the amount of TLB entries the
80	kernel flushes one-by-one instead of doing a full TLB flush. In
81	certain situations, the former is cheaper. This is controlled by the
82	tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
83	to -1, the code flushes the whole TLB unconditionally. Otherwise,
84	for positive values of it, the kernel will use single TLB entry
85	invalidating instructions according to the following formula:
86
87	flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
88
89	If in doubt, say "N".
90
91config IOMMU_DEBUG
92	bool "Enable IOMMU debugging"
93	depends on GART_IOMMU && DEBUG_KERNEL
94	depends on X86_64
95	help
96	  Force the IOMMU to on even when you have less than 4GB of
97	  memory and add debugging code. On overflow always panic. And
98	  allow to enable IOMMU leak tracing. Can be disabled at boot
99	  time with iommu=noforce. This will also enable scatter gather
100	  list merging.  Currently not recommended for production
101	  code. When you use it make sure you have a big enough
102	  IOMMU/AGP aperture.  Most of the options enabled by this can
103	  be set more finegrained using the iommu= command line
104	  options. See Documentation/x86/x86_64/boot-options.rst for more
105	  details.
106
107config IOMMU_LEAK
108	bool "IOMMU leak tracing"
109	depends on IOMMU_DEBUG && DMA_API_DEBUG
110	help
111	  Add a simple leak tracer to the IOMMU code. This is useful when you
112	  are debugging a buggy device driver that leaks IOMMU mappings.
113
114config HAVE_MMIOTRACE_SUPPORT
115	def_bool y
116
117config X86_DECODER_SELFTEST
118	bool "x86 instruction decoder selftest"
119	depends on DEBUG_KERNEL && INSTRUCTION_DECODER
120	depends on !COMPILE_TEST
121	help
122	 Perform x86 instruction decoder selftests at build time.
123	 This option is useful for checking the sanity of x86 instruction
124	 decoder code.
125	 If unsure, say "N".
126
127choice
128	prompt "IO delay type"
129	default IO_DELAY_0X80
130
131config IO_DELAY_0X80
132	bool "port 0x80 based port-IO delay [recommended]"
133	help
134	  This is the traditional Linux IO delay used for in/out_p.
135	  It is the most tested hence safest selection here.
136
137config IO_DELAY_0XED
138	bool "port 0xed based port-IO delay"
139	help
140	  Use port 0xed as the IO delay. This frees up port 0x80 which is
141	  often used as a hardware-debug port.
142
143config IO_DELAY_UDELAY
144	bool "udelay based port-IO delay"
145	help
146	  Use udelay(2) as the IO delay method. This provides the delay
147	  while not having any side-effect on the IO port space.
148
149config IO_DELAY_NONE
150	bool "no port-IO delay"
151	help
152	  No port-IO delay. Will break on old boxes that require port-IO
153	  delay for certain operations. Should work on most new machines.
154
155endchoice
156
157config DEBUG_BOOT_PARAMS
158	bool "Debug boot parameters"
159	depends on DEBUG_KERNEL
160	depends on DEBUG_FS
161	help
162	  This option will cause struct boot_params to be exported via debugfs.
163
164config CPA_DEBUG
165	bool "CPA self-test code"
166	depends on DEBUG_KERNEL
167	help
168	  Do change_page_attr() self-tests every 30 seconds.
169
170config DEBUG_ENTRY
171	bool "Debug low-level entry code"
172	depends on DEBUG_KERNEL
173	help
174	  This option enables sanity checks in x86's low-level entry code.
175	  Some of these sanity checks may slow down kernel entries and
176	  exits or otherwise impact performance.
177
178	  If unsure, say N.
179
180config DEBUG_NMI_SELFTEST
181	bool "NMI Selftest"
182	depends on DEBUG_KERNEL && X86_LOCAL_APIC
183	help
184	  Enabling this option turns on a quick NMI selftest to verify
185	  that the NMI behaves correctly.
186
187	  This might help diagnose strange hangs that rely on NMI to
188	  function properly.
189
190	  If unsure, say N.
191
192config DEBUG_IMR_SELFTEST
193	bool "Isolated Memory Region self test"
194	depends on INTEL_IMR
195	help
196	  This option enables automated sanity testing of the IMR code.
197	  Some simple tests are run to verify IMR bounds checking, alignment
198	  and overlapping. This option is really only useful if you are
199	  debugging an IMR memory map or are modifying the IMR code and want to
200	  test your changes.
201
202	  If unsure say N here.
203
204config X86_DEBUG_FPU
205	bool "Debug the x86 FPU code"
206	depends on DEBUG_KERNEL
207	default y
208	help
209	  If this option is enabled then there will be extra sanity
210	  checks and (boot time) debug printouts added to the kernel.
211	  This debugging adds some small amount of runtime overhead
212	  to the kernel.
213
214	  If unsure, say N.
215
216config PUNIT_ATOM_DEBUG
217	tristate "ATOM Punit debug driver"
218	depends on PCI
219	select DEBUG_FS
220	select IOSF_MBI
221	help
222	  This is a debug driver, which gets the power states
223	  of all Punit North Complex devices. The power states of
224	  each device is exposed as part of the debugfs interface.
225	  The current power state can be read from
226	  /sys/kernel/debug/punit_atom/dev_power_state
227
228choice
229	prompt "Choose kernel unwinder"
230	default UNWINDER_ORC if X86_64
231	default UNWINDER_FRAME_POINTER if X86_32
232	help
233	  This determines which method will be used for unwinding kernel stack
234	  traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack,
235	  livepatch, lockdep, and more.
236
237config UNWINDER_ORC
238	bool "ORC unwinder"
239	depends on X86_64
240	select STACK_VALIDATION
241	help
242	  This option enables the ORC (Oops Rewind Capability) unwinder for
243	  unwinding kernel stack traces.  It uses a custom data format which is
244	  a simplified version of the DWARF Call Frame Information standard.
245
246	  This unwinder is more accurate across interrupt entry frames than the
247	  frame pointer unwinder.  It also enables a 5-10% performance
248	  improvement across the entire kernel compared to frame pointers.
249
250	  Enabling this option will increase the kernel's runtime memory usage
251	  by roughly 2-4MB, depending on your kernel config.
252
253config UNWINDER_FRAME_POINTER
254	bool "Frame pointer unwinder"
255	select FRAME_POINTER
256	help
257	  This option enables the frame pointer unwinder for unwinding kernel
258	  stack traces.
259
260	  The unwinder itself is fast and it uses less RAM than the ORC
261	  unwinder, but the kernel text size will grow by ~3% and the kernel's
262	  overall performance will degrade by roughly 5-10%.
263
264config UNWINDER_GUESS
265	bool "Guess unwinder"
266	depends on EXPERT
267	depends on !STACKDEPOT
268	help
269	  This option enables the "guess" unwinder for unwinding kernel stack
270	  traces.  It scans the stack and reports every kernel text address it
271	  finds.  Some of the addresses it reports may be incorrect.
272
273	  While this option often produces false positives, it can still be
274	  useful in many cases.  Unlike the other unwinders, it has no runtime
275	  overhead.
276
277endchoice
278
279config FRAME_POINTER
280	depends on !UNWINDER_ORC && !UNWINDER_GUESS
281	bool
282