3 config TRACE_IRQFLAGS_SUPPORT
6 source "lib/Kconfig.debug"
9 bool "Filter access to /dev/mem"
11 If this option is disabled, you allow userspace (root) access to all
12 of memory, including kernel and userspace memory. Accidental
13 access to this is obviously disastrous, but specific access can
14 be used by people debugging the kernel. Note that with PAT support
15 enabled, even in this case there are restrictions on /dev/mem
16 use due to the cache aliasing requirements.
18 If this option is switched on, the /dev/mem file only allows
19 userspace access to PCI space and the BIOS code and data regions.
20 This is sufficient for dosemu and X and all common users of
25 config X86_VERBOSE_BOOTUP
26 bool "Enable verbose x86 bootup info messages"
29 Enables the informational output from the decompression stage
30 (e.g. bzImage) of the boot. If you disable this you will still
31 see errors. Disable this if you want silent bootup.
34 bool "Early printk" if EXPERT
37 Write kernel log output directly into the VGA buffer or to a serial
40 This is useful for kernel debugging when your machine crashes very
41 early before the console code is initialized. For normal operation
42 it is not recommended because it looks ugly and doesn't cooperate
43 with klogd/syslogd or the X server. You should normally N here,
44 unless you want to debug such a crash.
46 config EARLY_PRINTK_DBGP
47 bool "Early printk via EHCI debug port"
48 depends on EARLY_PRINTK && PCI
50 Write kernel log output directly into the EHCI debug port.
52 This is useful for kernel debugging when your machine crashes very
53 early before the console code is initialized. For normal operation
54 it is not recommended because it looks ugly and doesn't cooperate
55 with klogd/syslogd or the X server. You should normally N here,
56 unless you want to debug such a crash. You need usb debug device.
58 config EARLY_PRINTK_EFI
59 bool "Early printk via the EFI framebuffer"
60 depends on EFI && EARLY_PRINTK
63 Write kernel log output directly into the EFI framebuffer.
65 This is useful for kernel debugging when your machine crashes very
66 early before the console code is initialized.
68 config X86_PTDUMP_CORE
72 bool "Export kernel pagetable layout to userspace via debugfs"
73 depends on DEBUG_KERNEL
75 select X86_PTDUMP_CORE
77 Say Y here if you want to show the kernel pagetable layout in a
78 debugfs file. This information is only useful for kernel developers
79 who are working in architecture specific areas of the kernel.
80 It is probably not a good idea to enable this feature in a production
85 bool "Dump the EFI pagetable"
87 select X86_PTDUMP_CORE
89 Enable this if you want to dump the EFI page table before
90 enabling virtual mode. This can be used to debug miscellaneous
91 issues with the mapping of the EFI runtime regions into that
94 config DEBUG_RODATA_TEST
95 bool "Testcase for the marking rodata read-only"
98 This option enables a testcase for the setting rodata read-only
99 as well as for the change_page_attr() infrastructure.
103 bool "Warn on W+X mappings at boot"
104 select X86_PTDUMP_CORE
106 Generate a warning if any W+X mappings are found at boot.
108 This is useful for discovering cases where the kernel is leaving
109 W+X mappings after applying NX, as such mappings are a security risk.
111 Look for a message in dmesg output like this:
113 x86/mm: Checked W+X mappings: passed, no W+X pages found.
115 or like this, if the check failed:
117 x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found.
119 Note that even if the check fails, your kernel is possibly
120 still fine, as W+X mappings are not a security hole in
121 themselves, what they do is that they make the exploitation
122 of other unfixed kernel bugs easier.
124 There is no runtime or memory usage effect of this option
125 once the kernel has booted up - it's a one time check.
127 If in doubt, say "Y".
129 config DEBUG_SET_MODULE_RONX
130 bool "Set loadable kernel module data as NX and text as RO"
133 This option helps catch unintended modifications to loadable
134 kernel module's text and read-only data. It also prevents execution
135 of module data. Such protection may interfere with run-time code
136 patching and dynamic kernel tracing - and they might also protect
137 against certain classes of kernel exploits.
138 If in doubt, say "N".
141 tristate "Testcase for the NX non-executable stack feature"
142 depends on DEBUG_KERNEL && m
144 This option enables a testcase for the CPU NX capability
145 and the software setup of this feature.
150 bool "Enable doublefault exception handler" if EXPERT
152 This option allows trapping of rare doublefault exceptions that
153 would otherwise cause a system to silently reboot. Disabling this
154 option saves about 4k and might cause you much additional grey
157 config DEBUG_TLBFLUSH
158 bool "Set upper limit of TLB entries to flush one-by-one"
159 depends on DEBUG_KERNEL
164 This option allows the user to tune the amount of TLB entries the
165 kernel flushes one-by-one instead of doing a full TLB flush. In
166 certain situations, the former is cheaper. This is controlled by the
167 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
168 to -1, the code flushes the whole TLB unconditionally. Otherwise,
169 for positive values of it, the kernel will use single TLB entry
170 invalidating instructions according to the following formula:
172 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
174 If in doubt, say "N".
177 bool "Enable IOMMU debugging"
178 depends on GART_IOMMU && DEBUG_KERNEL
181 Force the IOMMU to on even when you have less than 4GB of
182 memory and add debugging code. On overflow always panic. And
183 allow to enable IOMMU leak tracing. Can be disabled at boot
184 time with iommu=noforce. This will also enable scatter gather
185 list merging. Currently not recommended for production
186 code. When you use it make sure you have a big enough
187 IOMMU/AGP aperture. Most of the options enabled by this can
188 be set more finegrained using the iommu= command line
189 options. See Documentation/x86/x86_64/boot-options.txt for more
193 bool "Enable IOMMU stress-test mode"
195 This option disables various optimizations in IOMMU related
196 code to do real stress testing of the IOMMU code. This option
197 will cause a performance drop and should only be enabled for
201 bool "IOMMU leak tracing"
202 depends on IOMMU_DEBUG && DMA_API_DEBUG
204 Add a simple leak tracer to the IOMMU code. This is useful when you
205 are debugging a buggy device driver that leaks IOMMU mappings.
207 config HAVE_MMIOTRACE_SUPPORT
210 config X86_DECODER_SELFTEST
211 bool "x86 instruction decoder selftest"
212 depends on DEBUG_KERNEL && KPROBES
213 depends on !COMPILE_TEST
215 Perform x86 instruction decoder selftests at build time.
216 This option is useful for checking the sanity of x86 instruction
224 config IO_DELAY_TYPE_0X80
228 config IO_DELAY_TYPE_0XED
232 config IO_DELAY_TYPE_UDELAY
236 config IO_DELAY_TYPE_NONE
241 prompt "IO delay type"
242 default IO_DELAY_0X80
245 bool "port 0x80 based port-IO delay [recommended]"
247 This is the traditional Linux IO delay used for in/out_p.
248 It is the most tested hence safest selection here.
251 bool "port 0xed based port-IO delay"
253 Use port 0xed as the IO delay. This frees up port 0x80 which is
254 often used as a hardware-debug port.
256 config IO_DELAY_UDELAY
257 bool "udelay based port-IO delay"
259 Use udelay(2) as the IO delay method. This provides the delay
260 while not having any side-effect on the IO port space.
263 bool "no port-IO delay"
265 No port-IO delay. Will break on old boxes that require port-IO
266 delay for certain operations. Should work on most new machines.
271 config DEFAULT_IO_DELAY_TYPE
273 default IO_DELAY_TYPE_0X80
277 config DEFAULT_IO_DELAY_TYPE
279 default IO_DELAY_TYPE_0XED
283 config DEFAULT_IO_DELAY_TYPE
285 default IO_DELAY_TYPE_UDELAY
289 config DEFAULT_IO_DELAY_TYPE
291 default IO_DELAY_TYPE_NONE
294 config DEBUG_BOOT_PARAMS
295 bool "Debug boot parameters"
296 depends on DEBUG_KERNEL
299 This option will cause struct boot_params to be exported via debugfs.
302 bool "CPA self-test code"
303 depends on DEBUG_KERNEL
305 Do change_page_attr() self-tests every 30 seconds.
307 config OPTIMIZE_INLINING
308 bool "Allow gcc to uninline functions marked 'inline'"
310 This option determines if the kernel forces gcc to inline the functions
311 developers have marked 'inline'. Doing so takes away freedom from gcc to
312 do what it thinks is best, which is desirable for the gcc 3.x series of
313 compilers. The gcc 4.x series have a rewritten inlining algorithm and
314 enabling this option will generate a smaller kernel there. Hopefully
315 this algorithm is so good that allowing gcc 4.x and above to make the
316 decision will become the default in the future. Until then this option
317 is there to test gcc for this.
322 bool "Debug low-level entry code"
323 depends on DEBUG_KERNEL
325 This option enables sanity checks in x86's low-level entry code.
326 Some of these sanity checks may slow down kernel entries and
327 exits or otherwise impact performance.
329 This is currently used to help test NMI code.
333 config DEBUG_NMI_SELFTEST
335 depends on DEBUG_KERNEL && X86_LOCAL_APIC
337 Enabling this option turns on a quick NMI selftest to verify
338 that the NMI behaves correctly.
340 This might help diagnose strange hangs that rely on NMI to
345 config DEBUG_IMR_SELFTEST
346 bool "Isolated Memory Region self test"
350 This option enables automated sanity testing of the IMR code.
351 Some simple tests are run to verify IMR bounds checking, alignment
352 and overlapping. This option is really only useful if you are
353 debugging an IMR memory map or are modifying the IMR code and want to
356 If unsure say N here.
358 config X86_DEBUG_STATIC_CPU_HAS
359 bool "Debug alternatives"
360 depends on DEBUG_KERNEL
362 This option causes additional code to be generated which
363 fails if static_cpu_has() is used before alternatives have
369 bool "Debug the x86 FPU code"
370 depends on DEBUG_KERNEL
373 If this option is enabled then there will be extra sanity
374 checks and (boot time) debug printouts added to the kernel.
375 This debugging adds some small amount of runtime overhead
380 config PUNIT_ATOM_DEBUG
381 tristate "ATOM Punit debug driver"
385 This is a debug driver, which gets the power states
386 of all Punit North Complex devices. The power states of
387 each device is exposed as part of the debugfs interface.
388 The current power state can be read from
389 /sys/kernel/debug/punit_atom/dev_power_state