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_MRST
47 bool "Early printk for MRST platform support"
48 depends on EARLY_PRINTK && X86_MRST
50 config EARLY_PRINTK_DBGP
51 bool "Early printk via EHCI debug port"
52 depends on EARLY_PRINTK && PCI
54 Write kernel log output directly into the EHCI debug port.
56 This is useful for kernel debugging when your machine crashes very
57 early before the console code is initialized. For normal operation
58 it is not recommended because it looks ugly and doesn't cooperate
59 with klogd/syslogd or the X server. You should normally N here,
60 unless you want to debug such a crash. You need usb debug device.
62 config DEBUG_STACKOVERFLOW
63 bool "Check for stack overflows"
64 depends on DEBUG_KERNEL
66 This option will cause messages to be printed if free stack space
67 drops below a certain limit.
69 config DEBUG_STACK_USAGE
70 bool "Stack utilization instrumentation"
71 depends on DEBUG_KERNEL
73 Enables the display of the minimum amount of free stack which each
74 task has ever had available in the sysrq-T and sysrq-P debug output.
76 This option will slow down process creation somewhat.
78 config DEBUG_PER_CPU_MAPS
79 bool "Debug access to per_cpu maps"
80 depends on DEBUG_KERNEL
83 Say Y to verify that the per_cpu map being accessed has
84 been setup. Adds a fair amount of code to kernel memory
85 and decreases performance.
90 bool "Export kernel pagetable layout to userspace via debugfs"
91 depends on DEBUG_KERNEL
94 Say Y here if you want to show the kernel pagetable layout in a
95 debugfs file. This information is only useful for kernel developers
96 who are working in architecture specific areas of the kernel.
97 It is probably not a good idea to enable this feature in a production
102 bool "Write protect kernel read-only data structures"
104 depends on DEBUG_KERNEL
106 Mark the kernel read-only data as write-protected in the pagetables,
107 in order to catch accidental (and incorrect) writes to such const
108 data. This is recommended so that we can catch kernel bugs sooner.
109 If in doubt, say "Y".
111 config DEBUG_RODATA_TEST
112 bool "Testcase for the DEBUG_RODATA feature"
113 depends on DEBUG_RODATA
116 This option enables a testcase for the DEBUG_RODATA
117 feature as well as for the change_page_attr() infrastructure.
121 tristate "Testcase for the NX non-executable stack feature"
122 depends on DEBUG_KERNEL && m
124 This option enables a testcase for the CPU NX capability
125 and the software setup of this feature.
129 bool "Use 4Kb for kernel stacks instead of 8Kb"
132 If you say Y here the kernel will use a 4Kb stacksize for the
133 kernel stack attached to each process/thread. This facilitates
134 running more threads on a system and also reduces the pressure
135 on the VM subsystem for higher order allocations. This option
136 will also use IRQ stacks to compensate for the reduced stackspace.
140 bool "Enable doublefault exception handler" if EMBEDDED
143 This option allows trapping of rare doublefault exceptions that
144 would otherwise cause a system to silently reboot. Disabling this
145 option saves about 4k and might cause you much additional grey
149 bool "Enable IOMMU debugging"
150 depends on GART_IOMMU && DEBUG_KERNEL
153 Force the IOMMU to on even when you have less than 4GB of
154 memory and add debugging code. On overflow always panic. And
155 allow to enable IOMMU leak tracing. Can be disabled at boot
156 time with iommu=noforce. This will also enable scatter gather
157 list merging. Currently not recommended for production
158 code. When you use it make sure you have a big enough
159 IOMMU/AGP aperture. Most of the options enabled by this can
160 be set more finegrained using the iommu= command line
161 options. See Documentation/x86_64/boot-options.txt for more
165 bool "Enable IOMMU stress-test mode"
167 This option disables various optimizations in IOMMU related
168 code to do real stress testing of the IOMMU code. This option
169 will cause a performance drop and should only be enabled for
173 bool "IOMMU leak tracing"
174 depends on IOMMU_DEBUG && DMA_API_DEBUG
176 Add a simple leak tracer to the IOMMU code. This is useful when you
177 are debugging a buggy device driver that leaks IOMMU mappings.
179 config HAVE_MMIOTRACE_SUPPORT
182 config X86_DECODER_SELFTEST
183 bool "x86 instruction decoder selftest"
184 depends on DEBUG_KERNEL && KPROBES
186 Perform x86 instruction decoder selftests at build time.
187 This option is useful for checking the sanity of x86 instruction
195 config IO_DELAY_TYPE_0X80
199 config IO_DELAY_TYPE_0XED
203 config IO_DELAY_TYPE_UDELAY
207 config IO_DELAY_TYPE_NONE
212 prompt "IO delay type"
213 default IO_DELAY_0X80
216 bool "port 0x80 based port-IO delay [recommended]"
218 This is the traditional Linux IO delay used for in/out_p.
219 It is the most tested hence safest selection here.
222 bool "port 0xed based port-IO delay"
224 Use port 0xed as the IO delay. This frees up port 0x80 which is
225 often used as a hardware-debug port.
227 config IO_DELAY_UDELAY
228 bool "udelay based port-IO delay"
230 Use udelay(2) as the IO delay method. This provides the delay
231 while not having any side-effect on the IO port space.
234 bool "no port-IO delay"
236 No port-IO delay. Will break on old boxes that require port-IO
237 delay for certain operations. Should work on most new machines.
242 config DEFAULT_IO_DELAY_TYPE
244 default IO_DELAY_TYPE_0X80
248 config DEFAULT_IO_DELAY_TYPE
250 default IO_DELAY_TYPE_0XED
254 config DEFAULT_IO_DELAY_TYPE
256 default IO_DELAY_TYPE_UDELAY
260 config DEFAULT_IO_DELAY_TYPE
262 default IO_DELAY_TYPE_NONE
265 config DEBUG_BOOT_PARAMS
266 bool "Debug boot parameters"
267 depends on DEBUG_KERNEL
270 This option will cause struct boot_params to be exported via debugfs.
273 bool "CPA self-test code"
274 depends on DEBUG_KERNEL
276 Do change_page_attr() self-tests every 30 seconds.
278 config OPTIMIZE_INLINING
279 bool "Allow gcc to uninline functions marked 'inline'"
281 This option determines if the kernel forces gcc to inline the functions
282 developers have marked 'inline'. Doing so takes away freedom from gcc to
283 do what it thinks is best, which is desirable for the gcc 3.x series of
284 compilers. The gcc 4.x series have a rewritten inlining algorithm and
285 enabling this option will generate a smaller kernel there. Hopefully
286 this algorithm is so good that allowing gcc 4.x and above to make the
287 decision will become the default in the future. Until then this option
288 is there to test gcc for this.
292 config DEBUG_STRICT_USER_COPY_CHECKS
293 bool "Strict copy size checks"
294 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
296 Enabling this option turns a certain set of sanity checks for user
297 copy operations into compile time failures.
299 The copy_from_user() etc checks are there to help test if there
300 are sufficient security checks on the length argument of
301 the copy operation, by having gcc prove that the argument is
304 If unsure, or if you run an older (pre 4.4) gcc, say N.