3 config TRACE_IRQFLAGS_SUPPORT
6 source "lib/Kconfig.debug"
8 config EARLY_PRINTK_USB
11 config X86_VERBOSE_BOOTUP
12 bool "Enable verbose x86 bootup info messages"
15 Enables the informational output from the decompression stage
16 (e.g. bzImage) of the boot. If you disable this you will still
17 see errors. Disable this if you want silent bootup.
20 bool "Early printk" if EXPERT
23 Write kernel log output directly into the VGA buffer or to a serial
26 This is useful for kernel debugging when your machine crashes very
27 early before the console code is initialized. For normal operation
28 it is not recommended because it looks ugly and doesn't cooperate
29 with klogd/syslogd or the X server. You should normally say N here,
30 unless you want to debug such a crash.
32 config EARLY_PRINTK_DBGP
33 bool "Early printk via EHCI debug port"
34 depends on EARLY_PRINTK && PCI
35 select EARLY_PRINTK_USB
37 Write kernel log output directly into the EHCI debug port.
39 This is useful for kernel debugging when your machine crashes very
40 early before the console code is initialized. For normal operation
41 it is not recommended because it looks ugly and doesn't cooperate
42 with klogd/syslogd or the X server. You should normally say N here,
43 unless you want to debug such a crash. You need usb debug device.
45 config EARLY_PRINTK_EFI
46 bool "Early printk via the EFI framebuffer"
47 depends on EFI && EARLY_PRINTK
50 Write kernel log output directly into the EFI framebuffer.
52 This is useful for kernel debugging when your machine crashes very
53 early before the console code is initialized.
55 config EARLY_PRINTK_USB_XDBC
56 bool "Early printk via the xHCI debug port"
57 depends on EARLY_PRINTK && PCI
58 select EARLY_PRINTK_USB
60 Write kernel log output directly into the xHCI debug port.
62 One use for this feature is kernel debugging, for example when your
63 machine crashes very early before the regular console code is
64 initialized. Other uses include simpler, lockless logging instead of
65 a full-blown printk console driver + klogd.
67 For normal production environments this is normally not recommended,
68 because it doesn't feed events into klogd/syslogd and doesn't try to
69 print anything on the screen.
71 You should normally say N here, unless you want to debug early
72 crashes or need a very simple printk logging facility.
74 config X86_PTDUMP_CORE
78 tristate "Export kernel pagetable layout to userspace via debugfs"
79 depends on DEBUG_KERNEL
81 select X86_PTDUMP_CORE
83 Say Y here if you want to show the kernel pagetable layout in a
84 debugfs file. This information is only useful for kernel developers
85 who are working in architecture specific areas of the kernel.
86 It is probably not a good idea to enable this feature in a production
91 bool "Dump the EFI pagetable"
93 select X86_PTDUMP_CORE
95 Enable this if you want to dump the EFI page table before
96 enabling virtual mode. This can be used to debug miscellaneous
97 issues with the mapping of the EFI runtime regions into that
101 bool "Warn on W+X mappings at boot"
102 select X86_PTDUMP_CORE
104 Generate a warning if any W+X mappings are found at boot.
106 This is useful for discovering cases where the kernel is leaving
107 W+X mappings after applying NX, as such mappings are a security risk.
109 Look for a message in dmesg output like this:
111 x86/mm: Checked W+X mappings: passed, no W+X pages found.
113 or like this, if the check failed:
115 x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found.
117 Note that even if the check fails, your kernel is possibly
118 still fine, as W+X mappings are not a security hole in
119 themselves, what they do is that they make the exploitation
120 of other unfixed kernel bugs easier.
122 There is no runtime or memory usage effect of this option
123 once the kernel has booted up - it's a one time check.
125 If in doubt, say "Y".
129 bool "Enable doublefault exception handler" if EXPERT
131 This option allows trapping of rare doublefault exceptions that
132 would otherwise cause a system to silently reboot. Disabling this
133 option saves about 4k and might cause you much additional grey
136 config DEBUG_TLBFLUSH
137 bool "Set upper limit of TLB entries to flush one-by-one"
138 depends on DEBUG_KERNEL
143 This option allows the user to tune the amount of TLB entries the
144 kernel flushes one-by-one instead of doing a full TLB flush. In
145 certain situations, the former is cheaper. This is controlled by the
146 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
147 to -1, the code flushes the whole TLB unconditionally. Otherwise,
148 for positive values of it, the kernel will use single TLB entry
149 invalidating instructions according to the following formula:
151 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
153 If in doubt, say "N".
156 bool "Enable IOMMU debugging"
157 depends on GART_IOMMU && DEBUG_KERNEL
160 Force the IOMMU to on even when you have less than 4GB of
161 memory and add debugging code. On overflow always panic. And
162 allow to enable IOMMU leak tracing. Can be disabled at boot
163 time with iommu=noforce. This will also enable scatter gather
164 list merging. Currently not recommended for production
165 code. When you use it make sure you have a big enough
166 IOMMU/AGP aperture. Most of the options enabled by this can
167 be set more finegrained using the iommu= command line
168 options. See Documentation/x86/x86_64/boot-options.txt for more
172 bool "Enable IOMMU stress-test mode"
174 This option disables various optimizations in IOMMU related
175 code to do real stress testing of the IOMMU code. This option
176 will cause a performance drop and should only be enabled for
180 bool "IOMMU leak tracing"
181 depends on IOMMU_DEBUG && DMA_API_DEBUG
183 Add a simple leak tracer to the IOMMU code. This is useful when you
184 are debugging a buggy device driver that leaks IOMMU mappings.
186 config HAVE_MMIOTRACE_SUPPORT
189 config X86_DECODER_SELFTEST
190 bool "x86 instruction decoder selftest"
191 depends on DEBUG_KERNEL && KPROBES
192 depends on !COMPILE_TEST
194 Perform x86 instruction decoder selftests at build time.
195 This option is useful for checking the sanity of x86 instruction
203 config IO_DELAY_TYPE_0X80
207 config IO_DELAY_TYPE_0XED
211 config IO_DELAY_TYPE_UDELAY
215 config IO_DELAY_TYPE_NONE
220 prompt "IO delay type"
221 default IO_DELAY_0X80
224 bool "port 0x80 based port-IO delay [recommended]"
226 This is the traditional Linux IO delay used for in/out_p.
227 It is the most tested hence safest selection here.
230 bool "port 0xed based port-IO delay"
232 Use port 0xed as the IO delay. This frees up port 0x80 which is
233 often used as a hardware-debug port.
235 config IO_DELAY_UDELAY
236 bool "udelay based port-IO delay"
238 Use udelay(2) as the IO delay method. This provides the delay
239 while not having any side-effect on the IO port space.
242 bool "no port-IO delay"
244 No port-IO delay. Will break on old boxes that require port-IO
245 delay for certain operations. Should work on most new machines.
250 config DEFAULT_IO_DELAY_TYPE
252 default IO_DELAY_TYPE_0X80
256 config DEFAULT_IO_DELAY_TYPE
258 default IO_DELAY_TYPE_0XED
262 config DEFAULT_IO_DELAY_TYPE
264 default IO_DELAY_TYPE_UDELAY
268 config DEFAULT_IO_DELAY_TYPE
270 default IO_DELAY_TYPE_NONE
273 config DEBUG_BOOT_PARAMS
274 bool "Debug boot parameters"
275 depends on DEBUG_KERNEL
278 This option will cause struct boot_params to be exported via debugfs.
281 bool "CPA self-test code"
282 depends on DEBUG_KERNEL
284 Do change_page_attr() self-tests every 30 seconds.
286 config OPTIMIZE_INLINING
287 bool "Allow gcc to uninline functions marked 'inline'"
289 This option determines if the kernel forces gcc to inline the functions
290 developers have marked 'inline'. Doing so takes away freedom from gcc to
291 do what it thinks is best, which is desirable for the gcc 3.x series of
292 compilers. The gcc 4.x series have a rewritten inlining algorithm and
293 enabling this option will generate a smaller kernel there. Hopefully
294 this algorithm is so good that allowing gcc 4.x and above to make the
295 decision will become the default in the future. Until then this option
296 is there to test gcc for this.
301 bool "Debug low-level entry code"
302 depends on DEBUG_KERNEL
304 This option enables sanity checks in x86's low-level entry code.
305 Some of these sanity checks may slow down kernel entries and
306 exits or otherwise impact performance.
308 This is currently used to help test NMI code.
312 config DEBUG_NMI_SELFTEST
314 depends on DEBUG_KERNEL && X86_LOCAL_APIC
316 Enabling this option turns on a quick NMI selftest to verify
317 that the NMI behaves correctly.
319 This might help diagnose strange hangs that rely on NMI to
324 config DEBUG_IMR_SELFTEST
325 bool "Isolated Memory Region self test"
329 This option enables automated sanity testing of the IMR code.
330 Some simple tests are run to verify IMR bounds checking, alignment
331 and overlapping. This option is really only useful if you are
332 debugging an IMR memory map or are modifying the IMR code and want to
335 If unsure say N here.
338 bool "Debug the x86 FPU code"
339 depends on DEBUG_KERNEL
342 If this option is enabled then there will be extra sanity
343 checks and (boot time) debug printouts added to the kernel.
344 This debugging adds some small amount of runtime overhead
349 config PUNIT_ATOM_DEBUG
350 tristate "ATOM Punit debug driver"
355 This is a debug driver, which gets the power states
356 of all Punit North Complex devices. The power states of
357 each device is exposed as part of the debugfs interface.
358 The current power state can be read from
359 /sys/kernel/debug/punit_atom/dev_power_state