3 config TRACE_IRQFLAGS_SUPPORT
6 source "lib/Kconfig.debug"
9 bool "Allow unlimited access to /dev/mem"
12 If this option is left on, you allow userspace (root) access to all
13 of memory, including kernel and userspace memory. Accidental
14 access to this is obviously disastrous, but specific access can
15 be used by people debugging the kernel.
17 If this option is switched on, the /dev/mem file only allows
18 userspace access to PCI space and the BIOS code and data regions.
19 This is sufficient for dosemu and X and all common users of
24 config X86_VERBOSE_BOOTUP
25 bool "Enable verbose x86 bootup info messages"
28 Enables the informational output from the decompression stage
29 (e.g. bzImage) of the boot. If you disable this you will still
30 see errors. Disable this if you want silent bootup.
33 bool "Early printk" if EMBEDDED
36 Write kernel log output directly into the VGA buffer or to a serial
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 N here,
43 unless you want to debug such a crash.
45 config DEBUG_STACKOVERFLOW
46 bool "Check for stack overflows"
47 depends on DEBUG_KERNEL
49 This option will cause messages to be printed if free stack space
50 drops below a certain limit.
52 config DEBUG_STACK_USAGE
53 bool "Stack utilization instrumentation"
54 depends on DEBUG_KERNEL
56 Enables the display of the minimum amount of free stack which each
57 task has ever had available in the sysrq-T and sysrq-P debug output.
59 This option will slow down process creation somewhat.
61 config DEBUG_PAGEALLOC
62 bool "Debug page memory allocations"
63 depends on DEBUG_KERNEL
65 Unmap pages from the kernel linear mapping after free_pages().
66 This results in a large slowdown, but helps to find certain types
67 of memory corruptions.
69 config DEBUG_PER_CPU_MAPS
70 bool "Debug access to per_cpu maps"
71 depends on DEBUG_KERNEL
75 Say Y to verify that the per_cpu map being accessed has
76 been setup. Adds a fair amount of code to kernel memory
77 and decreases performance.
82 bool "Export kernel pagetable layout to userspace via debugfs"
83 depends on DEBUG_KERNEL
86 Say Y here if you want to show the kernel pagetable layout in a
87 debugfs file. This information is only useful for kernel developers
88 who are working in architecture specific areas of the kernel.
89 It is probably not a good idea to enable this feature in a production
94 bool "Write protect kernel read-only data structures"
96 depends on DEBUG_KERNEL
98 Mark the kernel read-only data as write-protected in the pagetables,
99 in order to catch accidental (and incorrect) writes to such const
100 data. This is recommended so that we can catch kernel bugs sooner.
101 If in doubt, say "Y".
103 config DIRECT_GBPAGES
104 bool "Enable gbpages-mapped kernel pagetables"
105 depends on DEBUG_KERNEL && EXPERIMENTAL && X86_64
107 Enable gigabyte pages support (if the CPU supports it). This can
108 improve the kernel's performance a tiny bit by reducing TLB
111 This is experimental code.
113 If in doubt, say "N".
115 config DEBUG_RODATA_TEST
116 bool "Testcase for the DEBUG_RODATA feature"
117 depends on DEBUG_RODATA
119 This option enables a testcase for the DEBUG_RODATA
120 feature as well as for the change_page_attr() infrastructure.
124 tristate "Testcase for the NX non-executable stack feature"
125 depends on DEBUG_KERNEL && m
127 This option enables a testcase for the CPU NX capability
128 and the software setup of this feature.
132 bool "Use 4Kb for kernel stacks instead of 8Kb"
135 If you say Y here the kernel will use a 4Kb stacksize for the
136 kernel stack attached to each process/thread. This facilitates
137 running more threads on a system and also reduces the pressure
138 on the VM subsystem for higher order allocations. This option
139 will also use IRQ stacks to compensate for the reduced stackspace.
143 bool "Enable doublefault exception handler" if EMBEDDED
146 This option allows trapping of rare doublefault exceptions that
147 would otherwise cause a system to silently reboot. Disabling this
148 option saves about 4k and might cause you much additional grey
152 bool "Enable IOMMU debugging"
153 depends on GART_IOMMU && DEBUG_KERNEL
156 Force the IOMMU to on even when you have less than 4GB of
157 memory and add debugging code. On overflow always panic. And
158 allow to enable IOMMU leak tracing. Can be disabled at boot
159 time with iommu=noforce. This will also enable scatter gather
160 list merging. Currently not recommended for production
161 code. When you use it make sure you have a big enough
162 IOMMU/AGP aperture. Most of the options enabled by this can
163 be set more finegrained using the iommu= command line
164 options. See Documentation/x86_64/boot-options.txt for more
168 bool "IOMMU leak tracing"
169 depends on DEBUG_KERNEL
170 depends on IOMMU_DEBUG
172 Add a simple leak tracer to the IOMMU code. This is useful when you
173 are debugging a buggy device driver that leaks IOMMU mappings.
175 config MMIOTRACE_HOOKS
179 bool "Memory mapped IO tracing"
180 depends on DEBUG_KERNEL && PCI
182 select MMIOTRACE_HOOKS
184 Mmiotrace traces Memory Mapped I/O access and is meant for
185 debugging and reverse engineering. It is called from the ioremap
186 implementation and works via page faults. Tracing is disabled by
187 default and can be enabled at run-time.
189 See Documentation/tracers/mmiotrace.txt.
190 If you are not helping to develop drivers, say N.
192 config MMIOTRACE_TEST
193 tristate "Test module for mmiotrace"
194 depends on MMIOTRACE && m
196 This is a dumb module for testing mmiotrace. It is very dangerous
197 as it will write garbage to IO memory starting at a given address.
198 However, it should be safe to use on e.g. unused portion of VRAM.
200 Say N, unless you absolutely know what you are doing.
206 config IO_DELAY_TYPE_0X80
210 config IO_DELAY_TYPE_0XED
214 config IO_DELAY_TYPE_UDELAY
218 config IO_DELAY_TYPE_NONE
223 prompt "IO delay type"
224 default IO_DELAY_0X80
227 bool "port 0x80 based port-IO delay [recommended]"
229 This is the traditional Linux IO delay used for in/out_p.
230 It is the most tested hence safest selection here.
233 bool "port 0xed based port-IO delay"
235 Use port 0xed as the IO delay. This frees up port 0x80 which is
236 often used as a hardware-debug port.
238 config IO_DELAY_UDELAY
239 bool "udelay based port-IO delay"
241 Use udelay(2) as the IO delay method. This provides the delay
242 while not having any side-effect on the IO port space.
245 bool "no port-IO delay"
247 No port-IO delay. Will break on old boxes that require port-IO
248 delay for certain operations. Should work on most new machines.
253 config DEFAULT_IO_DELAY_TYPE
255 default IO_DELAY_TYPE_0X80
259 config DEFAULT_IO_DELAY_TYPE
261 default IO_DELAY_TYPE_0XED
265 config DEFAULT_IO_DELAY_TYPE
267 default IO_DELAY_TYPE_UDELAY
271 config DEFAULT_IO_DELAY_TYPE
273 default IO_DELAY_TYPE_NONE
276 config DEBUG_BOOT_PARAMS
277 bool "Debug boot parameters"
278 depends on DEBUG_KERNEL
281 This option will cause struct boot_params to be exported via debugfs.
284 bool "CPA self-test code"
285 depends on DEBUG_KERNEL
287 Do change_page_attr() self-tests every 30 seconds.
289 config OPTIMIZE_INLINING
290 bool "Allow gcc to uninline functions marked 'inline'"
293 This option determines if the kernel forces gcc to inline the functions
294 developers have marked 'inline'. Doing so takes away freedom from gcc to
295 do what it thinks is best, which is desirable for the gcc 3.x series of
296 compilers. The gcc 4.x series have a rewritten inlining algorithm and
297 disabling this option will generate a smaller kernel there. Hopefully
298 this algorithm is so good that allowing gcc4 to make the decision can
299 become the default in the future, until then this option is there to