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
76 This option allows the user to tune the amount of TLB entries the
77 kernel flushes one-by-one instead of doing a full TLB flush. In
78 certain situations, the former is cheaper. This is controlled by the
79 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
80 to -1, the code flushes the whole TLB unconditionally. Otherwise,
81 for positive values of it, the kernel will use single TLB entry
82 invalidating instructions according to the following formula:
84 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
89 bool "Enable IOMMU debugging"
90 depends on GART_IOMMU && DEBUG_KERNEL
93 Force the IOMMU to on even when you have less than 4GB of
94 memory and add debugging code. On overflow always panic. And
95 allow to enable IOMMU leak tracing. Can be disabled at boot
96 time with iommu=noforce. This will also enable scatter gather
97 list merging. Currently not recommended for production
98 code. When you use it make sure you have a big enough
99 IOMMU/AGP aperture. Most of the options enabled by this can
100 be set more finegrained using the iommu= command line
101 options. See Documentation/x86/x86_64/boot-options.rst for more
105 bool "IOMMU leak tracing"
106 depends on IOMMU_DEBUG && DMA_API_DEBUG
108 Add a simple leak tracer to the IOMMU code. This is useful when you
109 are debugging a buggy device driver that leaks IOMMU mappings.
111 config HAVE_MMIOTRACE_SUPPORT
114 config X86_DECODER_SELFTEST
115 bool "x86 instruction decoder selftest"
116 depends on DEBUG_KERNEL && INSTRUCTION_DECODER
117 depends on !COMPILE_TEST
119 Perform x86 instruction decoder selftests at build time.
120 This option is useful for checking the sanity of x86 instruction
125 prompt "IO delay type"
126 default IO_DELAY_0X80
129 bool "port 0x80 based port-IO delay [recommended]"
131 This is the traditional Linux IO delay used for in/out_p.
132 It is the most tested hence safest selection here.
135 bool "port 0xed based port-IO delay"
137 Use port 0xed as the IO delay. This frees up port 0x80 which is
138 often used as a hardware-debug port.
140 config IO_DELAY_UDELAY
141 bool "udelay based port-IO delay"
143 Use udelay(2) as the IO delay method. This provides the delay
144 while not having any side-effect on the IO port space.
147 bool "no port-IO delay"
149 No port-IO delay. Will break on old boxes that require port-IO
150 delay for certain operations. Should work on most new machines.
154 config DEBUG_BOOT_PARAMS
155 bool "Debug boot parameters"
156 depends on DEBUG_KERNEL
159 This option will cause struct boot_params to be exported via debugfs.
162 bool "CPA self-test code"
163 depends on DEBUG_KERNEL
165 Do change_page_attr() self-tests every 30 seconds.
168 bool "Debug low-level entry code"
169 depends on DEBUG_KERNEL
171 This option enables sanity checks in x86's low-level entry code.
172 Some of these sanity checks may slow down kernel entries and
173 exits or otherwise impact performance.
177 config DEBUG_NMI_SELFTEST
179 depends on DEBUG_KERNEL && X86_LOCAL_APIC
181 Enabling this option turns on a quick NMI selftest to verify
182 that the NMI behaves correctly.
184 This might help diagnose strange hangs that rely on NMI to
189 config DEBUG_IMR_SELFTEST
190 bool "Isolated Memory Region self test"
193 This option enables automated sanity testing of the IMR code.
194 Some simple tests are run to verify IMR bounds checking, alignment
195 and overlapping. This option is really only useful if you are
196 debugging an IMR memory map or are modifying the IMR code and want to
199 If unsure say N here.
202 bool "Debug the x86 FPU code"
203 depends on DEBUG_KERNEL
206 If this option is enabled then there will be extra sanity
207 checks and (boot time) debug printouts added to the kernel.
208 This debugging adds some small amount of runtime overhead
213 config PUNIT_ATOM_DEBUG
214 tristate "ATOM Punit debug driver"
219 This is a debug driver, which gets the power states
220 of all Punit North Complex devices. The power states of
221 each device is exposed as part of the debugfs interface.
222 The current power state can be read from
223 /sys/kernel/debug/punit_atom/dev_power_state
226 prompt "Choose kernel unwinder"
227 default UNWINDER_ORC if X86_64
228 default UNWINDER_FRAME_POINTER if X86_32
230 This determines which method will be used for unwinding kernel stack
231 traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack,
232 livepatch, lockdep, and more.
237 select STACK_VALIDATION
239 This option enables the ORC (Oops Rewind Capability) unwinder for
240 unwinding kernel stack traces. It uses a custom data format which is
241 a simplified version of the DWARF Call Frame Information standard.
243 This unwinder is more accurate across interrupt entry frames than the
244 frame pointer unwinder. It also enables a 5-10% performance
245 improvement across the entire kernel compared to frame pointers.
247 Enabling this option will increase the kernel's runtime memory usage
248 by roughly 2-4MB, depending on your kernel config.
250 config UNWINDER_FRAME_POINTER
251 bool "Frame pointer unwinder"
254 This option enables the frame pointer unwinder for unwinding kernel
257 The unwinder itself is fast and it uses less RAM than the ORC
258 unwinder, but the kernel text size will grow by ~3% and the kernel's
259 overall performance will degrade by roughly 5-10%.
261 config UNWINDER_GUESS
262 bool "Guess unwinder"
264 depends on !STACKDEPOT
266 This option enables the "guess" unwinder for unwinding kernel stack
267 traces. It scans the stack and reports every kernel text address it
268 finds. Some of the addresses it reports may be incorrect.
270 While this option often produces false positives, it can still be
271 useful in many cases. Unlike the other unwinders, it has no runtime
277 depends on !UNWINDER_ORC && !UNWINDER_GUESS