3 config TRACE_IRQFLAGS_SUPPORT
6 source "lib/Kconfig.debug"
8 config X86_VERBOSE_BOOTUP
9 bool "Enable verbose x86 bootup info messages"
12 Enables the informational output from the decompression stage
13 (e.g. bzImage) of the boot. If you disable this you will still
14 see errors. Disable this if you want silent bootup.
17 bool "Early printk" if EXPERT
20 Write kernel log output directly into the VGA buffer or to a serial
23 This is useful for kernel debugging when your machine crashes very
24 early before the console code is initialized. For normal operation
25 it is not recommended because it looks ugly and doesn't cooperate
26 with klogd/syslogd or the X server. You should normally N here,
27 unless you want to debug such a crash.
29 config EARLY_PRINTK_DBGP
30 bool "Early printk via EHCI debug port"
31 depends on EARLY_PRINTK && PCI
33 Write kernel log output directly into the EHCI debug port.
35 This is useful for kernel debugging when your machine crashes very
36 early before the console code is initialized. For normal operation
37 it is not recommended because it looks ugly and doesn't cooperate
38 with klogd/syslogd or the X server. You should normally N here,
39 unless you want to debug such a crash. You need usb debug device.
41 config EARLY_PRINTK_EFI
42 bool "Early printk via the EFI framebuffer"
43 depends on EFI && EARLY_PRINTK
46 Write kernel log output directly into the EFI framebuffer.
48 This is useful for kernel debugging when your machine crashes very
49 early before the console code is initialized.
51 config X86_PTDUMP_CORE
55 tristate "Export kernel pagetable layout to userspace via debugfs"
56 depends on DEBUG_KERNEL
58 select X86_PTDUMP_CORE
60 Say Y here if you want to show the kernel pagetable layout in a
61 debugfs file. This information is only useful for kernel developers
62 who are working in architecture specific areas of the kernel.
63 It is probably not a good idea to enable this feature in a production
68 bool "Dump the EFI pagetable"
70 select X86_PTDUMP_CORE
72 Enable this if you want to dump the EFI page table before
73 enabling virtual mode. This can be used to debug miscellaneous
74 issues with the mapping of the EFI runtime regions into that
78 bool "Write protect kernel read-only data structures"
80 depends on DEBUG_KERNEL
82 Mark the kernel read-only data as write-protected in the pagetables,
83 in order to catch accidental (and incorrect) writes to such const
84 data. This is recommended so that we can catch kernel bugs sooner.
87 config DEBUG_RODATA_TEST
88 bool "Testcase for the DEBUG_RODATA feature"
89 depends on DEBUG_RODATA
92 This option enables a testcase for the DEBUG_RODATA
93 feature as well as for the change_page_attr() infrastructure.
97 bool "Warn on W+X mappings at boot"
98 depends on DEBUG_RODATA
99 select X86_PTDUMP_CORE
101 Generate a warning if any W+X mappings are found at boot.
103 This is useful for discovering cases where the kernel is leaving
104 W+X mappings after applying NX, as such mappings are a security risk.
106 Look for a message in dmesg output like this:
108 x86/mm: Checked W+X mappings: passed, no W+X pages found.
110 or like this, if the check failed:
112 x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found.
114 Note that even if the check fails, your kernel is possibly
115 still fine, as W+X mappings are not a security hole in
116 themselves, what they do is that they make the exploitation
117 of other unfixed kernel bugs easier.
119 There is no runtime or memory usage effect of this option
120 once the kernel has booted up - it's a one time check.
122 If in doubt, say "Y".
124 config DEBUG_SET_MODULE_RONX
125 bool "Set loadable kernel module data as NX and text as RO"
128 This option helps catch unintended modifications to loadable
129 kernel module's text and read-only data. It also prevents execution
130 of module data. Such protection may interfere with run-time code
131 patching and dynamic kernel tracing - and they might also protect
132 against certain classes of kernel exploits.
133 If in doubt, say "N".
136 tristate "Testcase for the NX non-executable stack feature"
137 depends on DEBUG_KERNEL && m
139 This option enables a testcase for the CPU NX capability
140 and the software setup of this feature.
145 bool "Enable doublefault exception handler" if EXPERT
147 This option allows trapping of rare doublefault exceptions that
148 would otherwise cause a system to silently reboot. Disabling this
149 option saves about 4k and might cause you much additional grey
152 config DEBUG_TLBFLUSH
153 bool "Set upper limit of TLB entries to flush one-by-one"
154 depends on DEBUG_KERNEL
159 This option allows the user to tune the amount of TLB entries the
160 kernel flushes one-by-one instead of doing a full TLB flush. In
161 certain situations, the former is cheaper. This is controlled by the
162 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
163 to -1, the code flushes the whole TLB unconditionally. Otherwise,
164 for positive values of it, the kernel will use single TLB entry
165 invalidating instructions according to the following formula:
167 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
169 If in doubt, say "N".
172 bool "Enable IOMMU debugging"
173 depends on GART_IOMMU && DEBUG_KERNEL
176 Force the IOMMU to on even when you have less than 4GB of
177 memory and add debugging code. On overflow always panic. And
178 allow to enable IOMMU leak tracing. Can be disabled at boot
179 time with iommu=noforce. This will also enable scatter gather
180 list merging. Currently not recommended for production
181 code. When you use it make sure you have a big enough
182 IOMMU/AGP aperture. Most of the options enabled by this can
183 be set more finegrained using the iommu= command line
184 options. See Documentation/x86/x86_64/boot-options.txt for more
188 bool "Enable IOMMU stress-test mode"
190 This option disables various optimizations in IOMMU related
191 code to do real stress testing of the IOMMU code. This option
192 will cause a performance drop and should only be enabled for
196 bool "IOMMU leak tracing"
197 depends on IOMMU_DEBUG && DMA_API_DEBUG
199 Add a simple leak tracer to the IOMMU code. This is useful when you
200 are debugging a buggy device driver that leaks IOMMU mappings.
202 config HAVE_MMIOTRACE_SUPPORT
205 config X86_DECODER_SELFTEST
206 bool "x86 instruction decoder selftest"
207 depends on DEBUG_KERNEL && KPROBES
208 depends on !COMPILE_TEST
210 Perform x86 instruction decoder selftests at build time.
211 This option is useful for checking the sanity of x86 instruction
219 config IO_DELAY_TYPE_0X80
223 config IO_DELAY_TYPE_0XED
227 config IO_DELAY_TYPE_UDELAY
231 config IO_DELAY_TYPE_NONE
236 prompt "IO delay type"
237 default IO_DELAY_0X80
240 bool "port 0x80 based port-IO delay [recommended]"
242 This is the traditional Linux IO delay used for in/out_p.
243 It is the most tested hence safest selection here.
246 bool "port 0xed based port-IO delay"
248 Use port 0xed as the IO delay. This frees up port 0x80 which is
249 often used as a hardware-debug port.
251 config IO_DELAY_UDELAY
252 bool "udelay based port-IO delay"
254 Use udelay(2) as the IO delay method. This provides the delay
255 while not having any side-effect on the IO port space.
258 bool "no port-IO delay"
260 No port-IO delay. Will break on old boxes that require port-IO
261 delay for certain operations. Should work on most new machines.
266 config DEFAULT_IO_DELAY_TYPE
268 default IO_DELAY_TYPE_0X80
272 config DEFAULT_IO_DELAY_TYPE
274 default IO_DELAY_TYPE_0XED
278 config DEFAULT_IO_DELAY_TYPE
280 default IO_DELAY_TYPE_UDELAY
284 config DEFAULT_IO_DELAY_TYPE
286 default IO_DELAY_TYPE_NONE
289 config DEBUG_BOOT_PARAMS
290 bool "Debug boot parameters"
291 depends on DEBUG_KERNEL
294 This option will cause struct boot_params to be exported via debugfs.
297 bool "CPA self-test code"
298 depends on DEBUG_KERNEL
300 Do change_page_attr() self-tests every 30 seconds.
302 config OPTIMIZE_INLINING
303 bool "Allow gcc to uninline functions marked 'inline'"
305 This option determines if the kernel forces gcc to inline the functions
306 developers have marked 'inline'. Doing so takes away freedom from gcc to
307 do what it thinks is best, which is desirable for the gcc 3.x series of
308 compilers. The gcc 4.x series have a rewritten inlining algorithm and
309 enabling this option will generate a smaller kernel there. Hopefully
310 this algorithm is so good that allowing gcc 4.x and above to make the
311 decision will become the default in the future. Until then this option
312 is there to test gcc for this.
317 bool "Debug low-level entry code"
318 depends on DEBUG_KERNEL
320 This option enables sanity checks in x86's low-level entry code.
321 Some of these sanity checks may slow down kernel entries and
322 exits or otherwise impact performance.
324 This is currently used to help test NMI code.
328 config DEBUG_NMI_SELFTEST
330 depends on DEBUG_KERNEL && X86_LOCAL_APIC
332 Enabling this option turns on a quick NMI selftest to verify
333 that the NMI behaves correctly.
335 This might help diagnose strange hangs that rely on NMI to
340 config DEBUG_IMR_SELFTEST
341 bool "Isolated Memory Region self test"
345 This option enables automated sanity testing of the IMR code.
346 Some simple tests are run to verify IMR bounds checking, alignment
347 and overlapping. This option is really only useful if you are
348 debugging an IMR memory map or are modifying the IMR code and want to
351 If unsure say N here.
353 config X86_DEBUG_STATIC_CPU_HAS
354 bool "Debug alternatives"
355 depends on DEBUG_KERNEL
357 This option causes additional code to be generated which
358 fails if static_cpu_has() is used before alternatives have
364 bool "Debug the x86 FPU code"
365 depends on DEBUG_KERNEL
368 If this option is enabled then there will be extra sanity
369 checks and (boot time) debug printouts added to the kernel.
370 This debugging adds some small amount of runtime overhead
375 config PUNIT_ATOM_DEBUG
376 tristate "ATOM Punit debug driver"
380 This is a debug driver, which gets the power states
381 of all Punit North Complex devices. The power states of
382 each device is exposed as part of the debugfs interface.
383 The current power state can be read from
384 /sys/kernel/debug/punit_atom/dev_power_state