3 config TRACE_IRQFLAGS_SUPPORT
6 source "lib/Kconfig.debug"
8 config NONPROMISC_DEVMEM
9 bool "Filter access to /dev/mem"
11 If this option is left off, you allow userspace 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.
16 If this option is switched on, the /dev/mem file only allows
17 userspace access to PCI space and the BIOS code and data regions.
18 This is sufficient for dosemu and X and all common users of
24 bool "Early printk" if EMBEDDED
27 Write kernel log output directly into the VGA buffer or to a serial
30 This is useful for kernel debugging when your machine crashes very
31 early before the console code is initialized. For normal operation
32 it is not recommended because it looks ugly and doesn't cooperate
33 with klogd/syslogd or the X server. You should normally N here,
34 unless you want to debug such a crash.
36 config DEBUG_STACKOVERFLOW
37 bool "Check for stack overflows"
38 depends on DEBUG_KERNEL
40 This option will cause messages to be printed if free stack space
41 drops below a certain limit.
43 config DEBUG_STACK_USAGE
44 bool "Stack utilization instrumentation"
45 depends on DEBUG_KERNEL
47 Enables the display of the minimum amount of free stack which each
48 task has ever had available in the sysrq-T and sysrq-P debug output.
50 This option will slow down process creation somewhat.
52 config DEBUG_PAGEALLOC
53 bool "Debug page memory allocations"
54 depends on DEBUG_KERNEL
56 Unmap pages from the kernel linear mapping after free_pages().
57 This results in a large slowdown, but helps to find certain types
58 of memory corruptions.
60 config DEBUG_PER_CPU_MAPS
61 bool "Debug access to per_cpu maps"
62 depends on DEBUG_KERNEL
66 Say Y to verify that the per_cpu map being accessed has
67 been setup. Adds a fair amount of code to kernel memory
68 and decreases performance.
73 bool "Export kernel pagetable layout to userspace via debugfs"
74 depends on DEBUG_KERNEL
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 "Write protect kernel read-only data structures"
87 depends on DEBUG_KERNEL
89 Mark the kernel read-only data as write-protected in the pagetables,
90 in order to catch accidental (and incorrect) writes to such const
91 data. This is recommended so that we can catch kernel bugs sooner.
95 bool "Enable gbpages-mapped kernel pagetables"
96 depends on DEBUG_KERNEL && EXPERIMENTAL && X86_64
98 Enable gigabyte pages support (if the CPU supports it). This can
99 improve the kernel's performance a tiny bit by reducing TLB
102 This is experimental code.
104 If in doubt, say "N".
106 config DEBUG_RODATA_TEST
107 bool "Testcase for the DEBUG_RODATA feature"
108 depends on DEBUG_RODATA
111 This option enables a testcase for the DEBUG_RODATA
112 feature as well as for the change_page_attr() infrastructure.
116 tristate "Testcase for the NX non-executable stack feature"
117 depends on DEBUG_KERNEL && m
119 This option enables a testcase for the CPU NX capability
120 and the software setup of this feature.
124 bool "Use 4Kb for kernel stacks instead of 8Kb"
127 If you say Y here the kernel will use a 4Kb stacksize for the
128 kernel stack attached to each process/thread. This facilitates
129 running more threads on a system and also reduces the pressure
130 on the VM subsystem for higher order allocations. This option
131 will also use IRQ stacks to compensate for the reduced stackspace.
133 config X86_FIND_SMP_CONFIG
135 depends on X86_LOCAL_APIC || X86_VOYAGER
140 depends on (X86_32 && (X86_LOCAL_APIC && !X86_VISWS)) || X86_64
144 bool "Enable doublefault exception handler" if EMBEDDED
147 This option allows trapping of rare doublefault exceptions that
148 would otherwise cause a system to silently reboot. Disabling this
149 option saves about 4k and might cause you much additional grey
153 bool "Enable IOMMU debugging"
154 depends on GART_IOMMU && DEBUG_KERNEL
157 Force the IOMMU to on even when you have less than 4GB of
158 memory and add debugging code. On overflow always panic. And
159 allow to enable IOMMU leak tracing. Can be disabled at boot
160 time with iommu=noforce. This will also enable scatter gather
161 list merging. Currently not recommended for production
162 code. When you use it make sure you have a big enough
163 IOMMU/AGP aperture. Most of the options enabled by this can
164 be set more finegrained using the iommu= command line
165 options. See Documentation/x86_64/boot-options.txt for more
169 bool "IOMMU leak tracing"
170 depends on DEBUG_KERNEL
171 depends on IOMMU_DEBUG
173 Add a simple leak tracer to the IOMMU code. This is useful when you
174 are debugging a buggy device driver that leaks IOMMU mappings.
180 config IO_DELAY_TYPE_0X80
184 config IO_DELAY_TYPE_0XED
188 config IO_DELAY_TYPE_UDELAY
192 config IO_DELAY_TYPE_NONE
197 prompt "IO delay type"
198 default IO_DELAY_0X80
201 bool "port 0x80 based port-IO delay [recommended]"
203 This is the traditional Linux IO delay used for in/out_p.
204 It is the most tested hence safest selection here.
207 bool "port 0xed based port-IO delay"
209 Use port 0xed as the IO delay. This frees up port 0x80 which is
210 often used as a hardware-debug port.
212 config IO_DELAY_UDELAY
213 bool "udelay based port-IO delay"
215 Use udelay(2) as the IO delay method. This provides the delay
216 while not having any side-effect on the IO port space.
219 bool "no port-IO delay"
221 No port-IO delay. Will break on old boxes that require port-IO
222 delay for certain operations. Should work on most new machines.
227 config DEFAULT_IO_DELAY_TYPE
229 default IO_DELAY_TYPE_0X80
233 config DEFAULT_IO_DELAY_TYPE
235 default IO_DELAY_TYPE_0XED
239 config DEFAULT_IO_DELAY_TYPE
241 default IO_DELAY_TYPE_UDELAY
245 config DEFAULT_IO_DELAY_TYPE
247 default IO_DELAY_TYPE_NONE
250 config DEBUG_BOOT_PARAMS
251 bool "Debug boot parameters"
252 depends on DEBUG_KERNEL
255 This option will cause struct boot_params to be exported via debugfs.
258 bool "CPA self-test code"
259 depends on DEBUG_KERNEL
261 Do change_page_attr() self-tests every 30 seconds.
263 config OPTIMIZE_INLINING
264 bool "Allow gcc to uninline functions marked 'inline'"
267 This option determines if the kernel forces gcc to inline the functions
268 developers have marked 'inline'. Doing so takes away freedom from gcc to
269 do what it thinks is best, which is desirable for the gcc 3.x series of
270 compilers. The gcc 4.x series have a rewritten inlining algorithm and
271 disabling this option will generate a smaller kernel there. Hopefully
272 this algorithm is so good that allowing gcc4 to make the decision can
273 become the default in the future, until then this option is there to