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
189 config X86_DECODER_SELFTEST
190 bool "x86 instruction decoder selftest"
191 depends on DEBUG_KERNEL && KPROBES
193 Perform x86 instruction decoder selftests at build time.
194 This option is useful for checking the sanity of x86 instruction
202 config IO_DELAY_TYPE_0X80
206 config IO_DELAY_TYPE_0XED
210 config IO_DELAY_TYPE_UDELAY
214 config IO_DELAY_TYPE_NONE
219 prompt "IO delay type"
220 default IO_DELAY_0X80
223 bool "port 0x80 based port-IO delay [recommended]"
225 This is the traditional Linux IO delay used for in/out_p.
226 It is the most tested hence safest selection here.
229 bool "port 0xed based port-IO delay"
231 Use port 0xed as the IO delay. This frees up port 0x80 which is
232 often used as a hardware-debug port.
234 config IO_DELAY_UDELAY
235 bool "udelay based port-IO delay"
237 Use udelay(2) as the IO delay method. This provides the delay
238 while not having any side-effect on the IO port space.
241 bool "no port-IO delay"
243 No port-IO delay. Will break on old boxes that require port-IO
244 delay for certain operations. Should work on most new machines.
249 config DEFAULT_IO_DELAY_TYPE
251 default IO_DELAY_TYPE_0X80
255 config DEFAULT_IO_DELAY_TYPE
257 default IO_DELAY_TYPE_0XED
261 config DEFAULT_IO_DELAY_TYPE
263 default IO_DELAY_TYPE_UDELAY
267 config DEFAULT_IO_DELAY_TYPE
269 default IO_DELAY_TYPE_NONE
272 config DEBUG_BOOT_PARAMS
273 bool "Debug boot parameters"
274 depends on DEBUG_KERNEL
277 This option will cause struct boot_params to be exported via debugfs.
280 bool "CPA self-test code"
281 depends on DEBUG_KERNEL
283 Do change_page_attr() self-tests every 30 seconds.
285 config OPTIMIZE_INLINING
286 bool "Allow gcc to uninline functions marked 'inline'"
288 This option determines if the kernel forces gcc to inline the functions
289 developers have marked 'inline'. Doing so takes away freedom from gcc to
290 do what it thinks is best, which is desirable for the gcc 3.x series of
291 compilers. The gcc 4.x series have a rewritten inlining algorithm and
292 enabling this option will generate a smaller kernel there. Hopefully
293 this algorithm is so good that allowing gcc 4.x and above to make the
294 decision will become the default in the future. Until then this option
295 is there to test gcc for this.
299 config DEBUG_STRICT_USER_COPY_CHECKS
300 bool "Strict copy size checks"
301 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
303 Enabling this option turns a certain set of sanity checks for user
304 copy operations into compile time failures.
306 The copy_from_user() etc checks are there to help test if there
307 are sufficient security checks on the length argument of
308 the copy operation, by having gcc prove that the argument is
311 If unsure, or if you run an older (pre 4.4) gcc, say N.