1 # SPDX-License-Identifier: GPL-2.0
3 config EARLY_PRINTK_USB
6 config X86_VERBOSE_BOOTUP
7 bool "Enable verbose x86 bootup info messages"
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.
15 bool "Early printk" if EXPERT
18 Write kernel log output directly into the VGA buffer or to a serial
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.
27 config EARLY_PRINTK_DBGP
28 bool "Early printk via EHCI debug port"
29 depends on EARLY_PRINTK && PCI
30 select EARLY_PRINTK_USB
32 Write kernel log output directly into the EHCI debug port.
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.
40 config EARLY_PRINTK_USB_XDBC
41 bool "Early printk via the xHCI debug port"
42 depends on EARLY_PRINTK && PCI
43 select EARLY_PRINTK_USB
45 Write kernel log output directly into the xHCI debug port.
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.
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.
56 You should normally say N here, unless you want to debug early
57 crashes or need a very simple printk logging facility.
60 bool "Dump the EFI pagetable"
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
70 bool "Set upper limit of TLB entries to flush one-by-one"
71 depends on DEBUG_KERNEL
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:
83 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
88 bool "Enable IOMMU debugging"
89 depends on GART_IOMMU && DEBUG_KERNEL
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
104 bool "IOMMU leak tracing"
105 depends on IOMMU_DEBUG && DMA_API_DEBUG
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.
110 config HAVE_MMIOTRACE_SUPPORT
113 config X86_DECODER_SELFTEST
114 bool "x86 instruction decoder selftest"
115 depends on DEBUG_KERNEL && INSTRUCTION_DECODER
116 depends on !COMPILE_TEST
118 Perform x86 instruction decoder selftests at build time.
119 This option is useful for checking the sanity of x86 instruction
124 prompt "IO delay type"
125 default IO_DELAY_0X80
128 bool "port 0x80 based port-IO delay [recommended]"
130 This is the traditional Linux IO delay used for in/out_p.
131 It is the most tested hence safest selection here.
134 bool "port 0xed based port-IO delay"
136 Use port 0xed as the IO delay. This frees up port 0x80 which is
137 often used as a hardware-debug port.
139 config IO_DELAY_UDELAY
140 bool "udelay based port-IO delay"
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.
146 bool "no port-IO delay"
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.
153 config DEBUG_BOOT_PARAMS
154 bool "Debug boot parameters"
155 depends on DEBUG_KERNEL
158 This option will cause struct boot_params to be exported via debugfs.
161 bool "CPA self-test code"
162 depends on DEBUG_KERNEL
164 Do change_page_attr() self-tests every 30 seconds.
167 bool "Debug low-level entry code"
168 depends on DEBUG_KERNEL
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.
176 config DEBUG_NMI_SELFTEST
178 depends on DEBUG_KERNEL && X86_LOCAL_APIC
180 Enabling this option turns on a quick NMI selftest to verify
181 that the NMI behaves correctly.
183 This might help diagnose strange hangs that rely on NMI to
188 config DEBUG_IMR_SELFTEST
189 bool "Isolated Memory Region self test"
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
198 If unsure say N here.
201 bool "Debug the x86 FPU code"
202 depends on DEBUG_KERNEL
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
212 config PUNIT_ATOM_DEBUG
213 tristate "ATOM Punit debug driver"
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
225 prompt "Choose kernel unwinder"
226 default UNWINDER_ORC if X86_64
227 default UNWINDER_FRAME_POINTER if X86_32
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.
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.
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.
246 Enabling this option will increase the kernel's runtime memory usage
247 by roughly 2-4MB, depending on your kernel config.
249 config UNWINDER_FRAME_POINTER
250 bool "Frame pointer unwinder"
253 This option enables the frame pointer unwinder for unwinding kernel
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%.
260 config UNWINDER_GUESS
261 bool "Guess unwinder"
263 depends on !STACKDEPOT
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.
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
276 depends on !UNWINDER_ORC && !UNWINDER_GUESS