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 FRAME_POINTER
252	help
253	  This option enables the frame pointer unwinder for unwinding kernel
254	  stack traces.
255
256	  The unwinder itself is fast and it uses less RAM than the ORC
257	  unwinder, but the kernel text size will grow by ~3% and the kernel's
258	  overall performance will degrade by roughly 5-10%.
259
260config UNWINDER_GUESS
261	bool "Guess unwinder"
262	depends on EXPERT
263	depends on !STACKDEPOT
264	help
265	  This option enables the "guess" unwinder for unwinding kernel stack
266	  traces.  It scans the stack and reports every kernel text address it
267	  finds.  Some of the addresses it reports may be incorrect.
268
269	  While this option often produces false positives, it can still be
270	  useful in many cases.  Unlike the other unwinders, it has no runtime
271	  overhead.
272
273endchoice
274
275config FRAME_POINTER
276	depends on !UNWINDER_ORC && !UNWINDER_GUESS
277	bool
278