1 # SPDX-License-Identifier: GPL-2.0
3 config TRACE_IRQFLAGS_NMI_SUPPORT
6 config EARLY_PRINTK_USB
9 config X86_VERBOSE_BOOTUP
10 bool "Enable verbose x86 bootup info messages"
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.
18 bool "Early printk" if EXPERT
21 Write kernel log output directly into the VGA buffer or to a serial
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.
30 config EARLY_PRINTK_DBGP
31 bool "Early printk via EHCI debug port"
32 depends on EARLY_PRINTK && PCI
33 select EARLY_PRINTK_USB
35 Write kernel log output directly into the EHCI debug port.
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.
43 config EARLY_PRINTK_USB_XDBC
44 bool "Early printk via the xHCI debug port"
45 depends on EARLY_PRINTK && PCI
46 select EARLY_PRINTK_USB
48 Write kernel log output directly into the xHCI debug port.
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.
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.
59 You should normally say N here, unless you want to debug early
60 crashes or need a very simple printk logging facility.
63 bool "Dump the EFI pagetable"
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
73 bool "Set upper limit of TLB entries to flush one-by-one"
74 depends on DEBUG_KERNEL
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:
87 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
92 bool "Enable IOMMU debugging"
93 depends on GART_IOMMU && DEBUG_KERNEL
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
108 bool "IOMMU leak tracing"
109 depends on IOMMU_DEBUG && DMA_API_DEBUG
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.
114 config HAVE_MMIOTRACE_SUPPORT
117 config X86_DECODER_SELFTEST
118 bool "x86 instruction decoder selftest"
119 depends on DEBUG_KERNEL && INSTRUCTION_DECODER
120 depends on !COMPILE_TEST
122 Perform x86 instruction decoder selftests at build time.
123 This option is useful for checking the sanity of x86 instruction
128 prompt "IO delay type"
129 default IO_DELAY_0X80
132 bool "port 0x80 based port-IO delay [recommended]"
134 This is the traditional Linux IO delay used for in/out_p.
135 It is the most tested hence safest selection here.
138 bool "port 0xed based port-IO delay"
140 Use port 0xed as the IO delay. This frees up port 0x80 which is
141 often used as a hardware-debug port.
143 config IO_DELAY_UDELAY
144 bool "udelay based port-IO delay"
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.
150 bool "no port-IO delay"
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.
157 config DEBUG_BOOT_PARAMS
158 bool "Debug boot parameters"
159 depends on DEBUG_KERNEL
162 This option will cause struct boot_params to be exported via debugfs.
165 bool "CPA self-test code"
166 depends on DEBUG_KERNEL
168 Do change_page_attr() self-tests every 30 seconds.
171 bool "Debug low-level entry code"
172 depends on DEBUG_KERNEL
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.
180 config DEBUG_NMI_SELFTEST
182 depends on DEBUG_KERNEL && X86_LOCAL_APIC
184 Enabling this option turns on a quick NMI selftest to verify
185 that the NMI behaves correctly.
187 This might help diagnose strange hangs that rely on NMI to
192 config DEBUG_IMR_SELFTEST
193 bool "Isolated Memory Region self test"
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
202 If unsure say N here.
205 bool "Debug the x86 FPU code"
206 depends on DEBUG_KERNEL
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
216 config PUNIT_ATOM_DEBUG
217 tristate "ATOM Punit debug driver"
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
229 prompt "Choose kernel unwinder"
230 default UNWINDER_ORC if X86_64
231 default UNWINDER_FRAME_POINTER if X86_32
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.
240 select STACK_VALIDATION
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.
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.
250 Enabling this option will increase the kernel's runtime memory usage
251 by roughly 2-4MB, depending on your kernel config.
253 config UNWINDER_FRAME_POINTER
254 bool "Frame pointer unwinder"
257 This option enables the frame pointer unwinder for unwinding kernel
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%.
264 config UNWINDER_GUESS
265 bool "Guess unwinder"
267 depends on !STACKDEPOT
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.
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
280 depends on !UNWINDER_ORC && !UNWINDER_GUESS