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
110 This option enables a testcase for the DEBUG_RODATA
111 feature as well as for the change_page_attr() infrastructure.
115 tristate "Testcase for the NX non-executable stack feature"
116 depends on DEBUG_KERNEL && m
118 This option enables a testcase for the CPU NX capability
119 and the software setup of this feature.
123 bool "Use 4Kb for kernel stacks instead of 8Kb"
126 If you say Y here the kernel will use a 4Kb stacksize for the
127 kernel stack attached to each process/thread. This facilitates
128 running more threads on a system and also reduces the pressure
129 on the VM subsystem for higher order allocations. This option
130 will also use IRQ stacks to compensate for the reduced stackspace.
132 config X86_FIND_SMP_CONFIG
134 depends on X86_LOCAL_APIC || X86_VOYAGER
139 depends on (X86_32 && (X86_LOCAL_APIC && !X86_VISWS)) || X86_64
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
185 Mmiotrace traces Memory Mapped I/O access and is meant for
186 debugging and reverse engineering. It is called from the ioremap
187 implementation and works via page faults. Tracing is disabled by
188 default and can be enabled at run-time.
190 See Documentation/tracers/mmiotrace.txt.
191 If you are not helping to develop drivers, say N.
193 config MMIOTRACE_TEST
194 tristate "Test module for mmiotrace"
195 depends on MMIOTRACE && m
197 This is a dumb module for testing mmiotrace. It is very dangerous
198 as it will write garbage to IO memory starting at a given address.
199 However, it should be safe to use on e.g. unused portion of VRAM.
201 Say N, unless you absolutely know what you are doing.
207 config IO_DELAY_TYPE_0X80
211 config IO_DELAY_TYPE_0XED
215 config IO_DELAY_TYPE_UDELAY
219 config IO_DELAY_TYPE_NONE
224 prompt "IO delay type"
225 default IO_DELAY_0X80
228 bool "port 0x80 based port-IO delay [recommended]"
230 This is the traditional Linux IO delay used for in/out_p.
231 It is the most tested hence safest selection here.
234 bool "port 0xed based port-IO delay"
236 Use port 0xed as the IO delay. This frees up port 0x80 which is
237 often used as a hardware-debug port.
239 config IO_DELAY_UDELAY
240 bool "udelay based port-IO delay"
242 Use udelay(2) as the IO delay method. This provides the delay
243 while not having any side-effect on the IO port space.
246 bool "no port-IO delay"
248 No port-IO delay. Will break on old boxes that require port-IO
249 delay for certain operations. Should work on most new machines.
254 config DEFAULT_IO_DELAY_TYPE
256 default IO_DELAY_TYPE_0X80
260 config DEFAULT_IO_DELAY_TYPE
262 default IO_DELAY_TYPE_0XED
266 config DEFAULT_IO_DELAY_TYPE
268 default IO_DELAY_TYPE_UDELAY
272 config DEFAULT_IO_DELAY_TYPE
274 default IO_DELAY_TYPE_NONE
277 config DEBUG_BOOT_PARAMS
278 bool "Debug boot parameters"
279 depends on DEBUG_KERNEL
282 This option will cause struct boot_params to be exported via debugfs.
285 bool "CPA self-test code"
286 depends on DEBUG_KERNEL
288 Do change_page_attr() self-tests every 30 seconds.
290 config OPTIMIZE_INLINING
291 bool "Allow gcc to uninline functions marked 'inline'"
294 This option determines if the kernel forces gcc to inline the functions
295 developers have marked 'inline'. Doing so takes away freedom from gcc to
296 do what it thinks is best, which is desirable for the gcc 3.x series of
297 compilers. The gcc 4.x series have a rewritten inlining algorithm and
298 disabling this option will generate a smaller kernel there. Hopefully
299 this algorithm is so good that allowing gcc4 to make the decision can
300 become the default in the future, until then this option is there to