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 EMBEDDED
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"
49 depends on EARLY_PRINTK && PCI
51 Write kernel log output directly into the EHCI debug port.
53 This is useful for kernel debugging when your machine crashes very
54 early before the console code is initialized. For normal operation
55 it is not recommended because it looks ugly and doesn't cooperate
56 with klogd/syslogd or the X server. You should normally N here,
57 unless you want to debug such a crash. You need usb debug device.
59 config DEBUG_STACKOVERFLOW
60 bool "Check for stack overflows"
61 depends on DEBUG_KERNEL
63 This option will cause messages to be printed if free stack space
64 drops below a certain limit.
66 config DEBUG_STACK_USAGE
67 bool "Stack utilization instrumentation"
68 depends on DEBUG_KERNEL
70 Enables the display of the minimum amount of free stack which each
71 task has ever had available in the sysrq-T and sysrq-P debug output.
73 This option will slow down process creation somewhat.
75 config DEBUG_PER_CPU_MAPS
76 bool "Debug access to per_cpu maps"
77 depends on DEBUG_KERNEL
81 Say Y to verify that the per_cpu map being accessed has
82 been setup. Adds a fair amount of code to kernel memory
83 and decreases performance.
88 bool "Export kernel pagetable layout to userspace via debugfs"
89 depends on DEBUG_KERNEL
92 Say Y here if you want to show the kernel pagetable layout in a
93 debugfs file. This information is only useful for kernel developers
94 who are working in architecture specific areas of the kernel.
95 It is probably not a good idea to enable this feature in a production
100 bool "Write protect kernel read-only data structures"
102 depends on DEBUG_KERNEL
104 Mark the kernel read-only data as write-protected in the pagetables,
105 in order to catch accidental (and incorrect) writes to such const
106 data. This is recommended so that we can catch kernel bugs sooner.
107 If in doubt, say "Y".
109 config DEBUG_RODATA_TEST
110 bool "Testcase for the DEBUG_RODATA feature"
111 depends on DEBUG_RODATA
114 This option enables a testcase for the DEBUG_RODATA
115 feature as well as for the change_page_attr() infrastructure.
119 tristate "Testcase for the NX non-executable stack feature"
120 depends on DEBUG_KERNEL && m
122 This option enables a testcase for the CPU NX capability
123 and the software setup of this feature.
127 bool "Use 4Kb for kernel stacks instead of 8Kb"
130 If you say Y here the kernel will use a 4Kb stacksize for the
131 kernel stack attached to each process/thread. This facilitates
132 running more threads on a system and also reduces the pressure
133 on the VM subsystem for higher order allocations. This option
134 will also use IRQ stacks to compensate for the reduced stackspace.
138 bool "Enable doublefault exception handler" if EMBEDDED
141 This option allows trapping of rare doublefault exceptions that
142 would otherwise cause a system to silently reboot. Disabling this
143 option saves about 4k and might cause you much additional grey
147 bool "Enable IOMMU debugging"
148 depends on GART_IOMMU && DEBUG_KERNEL
151 Force the IOMMU to on even when you have less than 4GB of
152 memory and add debugging code. On overflow always panic. And
153 allow to enable IOMMU leak tracing. Can be disabled at boot
154 time with iommu=noforce. This will also enable scatter gather
155 list merging. Currently not recommended for production
156 code. When you use it make sure you have a big enough
157 IOMMU/AGP aperture. Most of the options enabled by this can
158 be set more finegrained using the iommu= command line
159 options. See Documentation/x86_64/boot-options.txt for more
163 bool "Enable IOMMU stress-test mode"
165 This option disables various optimizations in IOMMU related
166 code to do real stress testing of the IOMMU code. This option
167 will cause a performance drop and should only be enabled for
171 bool "IOMMU leak tracing"
172 depends on IOMMU_DEBUG && DMA_API_DEBUG
174 Add a simple leak tracer to the IOMMU code. This is useful when you
175 are debugging a buggy device driver that leaks IOMMU mappings.
177 config X86_DS_SELFTEST
180 depends on DEBUG_KERNEL
183 Perform Debug Store selftests at boot time.
184 If in doubt, say "N".
186 config HAVE_MMIOTRACE_SUPPORT
193 config IO_DELAY_TYPE_0X80
197 config IO_DELAY_TYPE_0XED
201 config IO_DELAY_TYPE_UDELAY
205 config IO_DELAY_TYPE_NONE
210 prompt "IO delay type"
211 default IO_DELAY_0X80
214 bool "port 0x80 based port-IO delay [recommended]"
216 This is the traditional Linux IO delay used for in/out_p.
217 It is the most tested hence safest selection here.
220 bool "port 0xed based port-IO delay"
222 Use port 0xed as the IO delay. This frees up port 0x80 which is
223 often used as a hardware-debug port.
225 config IO_DELAY_UDELAY
226 bool "udelay based port-IO delay"
228 Use udelay(2) as the IO delay method. This provides the delay
229 while not having any side-effect on the IO port space.
232 bool "no port-IO delay"
234 No port-IO delay. Will break on old boxes that require port-IO
235 delay for certain operations. Should work on most new machines.
240 config DEFAULT_IO_DELAY_TYPE
242 default IO_DELAY_TYPE_0X80
246 config DEFAULT_IO_DELAY_TYPE
248 default IO_DELAY_TYPE_0XED
252 config DEFAULT_IO_DELAY_TYPE
254 default IO_DELAY_TYPE_UDELAY
258 config DEFAULT_IO_DELAY_TYPE
260 default IO_DELAY_TYPE_NONE
264 bool "kmemcheck: trap use of uninitialized memory"
265 depends on DEBUG_KERNEL
266 depends on !X86_USE_3DNOW
267 depends on SLUB || SLAB
268 depends on !CC_OPTIMIZE_FOR_SIZE
269 depends on !FUNCTION_TRACER
274 This option enables tracing of dynamically allocated kernel memory
275 to see if memory is used before it has been given an initial value.
276 Be aware that this requires half of your memory for bookkeeping and
277 will insert extra code at *every* read and write to tracked memory
278 thus slow down the kernel code (but user code is unaffected).
280 The kernel may be started with kmemcheck=0 or kmemcheck=1 to disable
281 or enable kmemcheck at boot-time. If the kernel is started with
282 kmemcheck=0, the large memory and CPU overhead is not incurred.
285 prompt "kmemcheck: default mode at boot"
287 default KMEMCHECK_ONESHOT_BY_DEFAULT
289 This option controls the default behaviour of kmemcheck when the
290 kernel boots and no kmemcheck= parameter is given.
292 config KMEMCHECK_DISABLED_BY_DEFAULT
296 config KMEMCHECK_ENABLED_BY_DEFAULT
300 config KMEMCHECK_ONESHOT_BY_DEFAULT
304 In one-shot mode, only the first error detected is reported before
305 kmemcheck is disabled.
309 config KMEMCHECK_QUEUE_SIZE
310 int "kmemcheck: error queue size"
314 Select the maximum number of errors to store in the queue. Since
315 errors can occur virtually anywhere and in any context, we need a
316 temporary storage area which is guarantueed not to generate any
317 other faults. The queue will be emptied as soon as a tasklet may
318 be scheduled. If the queue is full, new error reports will be
321 config KMEMCHECK_SHADOW_COPY_SHIFT
322 int "kmemcheck: shadow copy size (5 => 32 bytes, 6 => 64 bytes)"
327 Select the number of shadow bytes to save along with each entry of
328 the queue. These bytes indicate what parts of an allocation are
329 initialized, uninitialized, etc. and will be displayed when an
330 error is detected to help the debugging of a particular problem.
332 config KMEMCHECK_PARTIAL_OK
333 bool "kmemcheck: allow partially uninitialized memory"
337 This option works around certain GCC optimizations that produce
338 32-bit reads from 16-bit variables where the upper 16 bits are
339 thrown away afterwards. This may of course also hide some real
342 config KMEMCHECK_BITOPS_OK
343 bool "kmemcheck: allow bit-field manipulation"
347 This option silences warnings that would be generated for bit-field
348 accesses where not all the bits are initialized at the same time.
349 This may also hide some real bugs.
351 config DEBUG_BOOT_PARAMS
352 bool "Debug boot parameters"
353 depends on DEBUG_KERNEL
356 This option will cause struct boot_params to be exported via debugfs.
359 bool "CPA self-test code"
360 depends on DEBUG_KERNEL
362 Do change_page_attr() self-tests every 30 seconds.
364 config OPTIMIZE_INLINING
365 bool "Allow gcc to uninline functions marked 'inline'"
367 This option determines if the kernel forces gcc to inline the functions
368 developers have marked 'inline'. Doing so takes away freedom from gcc to
369 do what it thinks is best, which is desirable for the gcc 3.x series of
370 compilers. The gcc 4.x series have a rewritten inlining algorithm and
371 enabling this option will generate a smaller kernel there. Hopefully
372 this algorithm is so good that allowing gcc 4.x and above to make the
373 decision will become the default in the future. Until then this option
374 is there to test gcc for this.