3 config TRACE_IRQFLAGS_SUPPORT
6 source "lib/Kconfig.debug"
8 config NONPROMISC_DEVMEM
9 bool "Disable promiscuous /dev/mem"
11 The /dev/mem file by default only allows userspace access to PCI
12 space and the BIOS code and data regions. This is sufficient for
13 dosemu and X and all common users of /dev/mem. With this config
14 option, you allow userspace access to all of memory, including
15 kernel and userspace memory. Accidental access to this is
16 obviously disasterous, but specific access can be used by people
19 config X86_VERBOSE_BOOTUP
20 bool "Enable verbose x86 bootup info messages"
23 Enables the informational output from the decompression stage
24 (e.g. bzImage) of the boot. If you disable this you will still
25 see errors. Disable this if you want silent bootup.
28 bool "Early printk" if EMBEDDED
31 Write kernel log output directly into the VGA buffer or to a serial
34 This is useful for kernel debugging when your machine crashes very
35 early before the console code is initialized. For normal operation
36 it is not recommended because it looks ugly and doesn't cooperate
37 with klogd/syslogd or the X server. You should normally N here,
38 unless you want to debug such a crash.
40 config DEBUG_STACKOVERFLOW
41 bool "Check for stack overflows"
42 depends on DEBUG_KERNEL
44 This option will cause messages to be printed if free stack space
45 drops below a certain limit.
47 config DEBUG_STACK_USAGE
48 bool "Stack utilization instrumentation"
49 depends on DEBUG_KERNEL
51 Enables the display of the minimum amount of free stack which each
52 task has ever had available in the sysrq-T and sysrq-P debug output.
54 This option will slow down process creation somewhat.
56 config DEBUG_PAGEALLOC
57 bool "Debug page memory allocations"
58 depends on DEBUG_KERNEL
60 Unmap pages from the kernel linear mapping after free_pages().
61 This results in a large slowdown, but helps to find certain types
62 of memory corruptions.
64 config DEBUG_PER_CPU_MAPS
65 bool "Debug access to per_cpu maps"
66 depends on DEBUG_KERNEL
70 Say Y to verify that the per_cpu map being accessed has
71 been setup. Adds a fair amount of code to kernel memory
72 and decreases performance.
77 bool "Export kernel pagetable layout to userspace via debugfs"
78 depends on DEBUG_KERNEL
81 Say Y here if you want to show the kernel pagetable layout in a
82 debugfs file. This information is only useful for kernel developers
83 who are working in architecture specific areas of the kernel.
84 It is probably not a good idea to enable this feature in a production
89 bool "Write protect kernel read-only data structures"
91 depends on DEBUG_KERNEL
93 Mark the kernel read-only data as write-protected in the pagetables,
94 in order to catch accidental (and incorrect) writes to such const
95 data. This is recommended so that we can catch kernel bugs sooner.
99 bool "Enable gbpages-mapped kernel pagetables"
100 depends on DEBUG_KERNEL && EXPERIMENTAL && X86_64
102 Enable gigabyte pages support (if the CPU supports it). This can
103 improve the kernel's performance a tiny bit by reducing TLB
106 This is experimental code.
108 If in doubt, say "N".
110 config DEBUG_RODATA_TEST
111 bool "Testcase for the DEBUG_RODATA feature"
112 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.
136 config X86_FIND_SMP_CONFIG
138 depends on X86_LOCAL_APIC || X86_VOYAGER
143 depends on (X86_32 && (X86_LOCAL_APIC && !X86_VISWS)) || X86_64
147 bool "Enable doublefault exception handler" if EMBEDDED
150 This option allows trapping of rare doublefault exceptions that
151 would otherwise cause a system to silently reboot. Disabling this
152 option saves about 4k and might cause you much additional grey
156 bool "Enable IOMMU debugging"
157 depends on GART_IOMMU && DEBUG_KERNEL
160 Force the IOMMU to on even when you have less than 4GB of
161 memory and add debugging code. On overflow always panic. And
162 allow to enable IOMMU leak tracing. Can be disabled at boot
163 time with iommu=noforce. This will also enable scatter gather
164 list merging. Currently not recommended for production
165 code. When you use it make sure you have a big enough
166 IOMMU/AGP aperture. Most of the options enabled by this can
167 be set more finegrained using the iommu= command line
168 options. See Documentation/x86_64/boot-options.txt for more
172 bool "IOMMU leak tracing"
173 depends on DEBUG_KERNEL
174 depends on IOMMU_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.
183 config IO_DELAY_TYPE_0X80
187 config IO_DELAY_TYPE_0XED
191 config IO_DELAY_TYPE_UDELAY
195 config IO_DELAY_TYPE_NONE
200 prompt "IO delay type"
201 default IO_DELAY_0X80
204 bool "port 0x80 based port-IO delay [recommended]"
206 This is the traditional Linux IO delay used for in/out_p.
207 It is the most tested hence safest selection here.
210 bool "port 0xed based port-IO delay"
212 Use port 0xed as the IO delay. This frees up port 0x80 which is
213 often used as a hardware-debug port.
215 config IO_DELAY_UDELAY
216 bool "udelay based port-IO delay"
218 Use udelay(2) as the IO delay method. This provides the delay
219 while not having any side-effect on the IO port space.
222 bool "no port-IO delay"
224 No port-IO delay. Will break on old boxes that require port-IO
225 delay for certain operations. Should work on most new machines.
230 config DEFAULT_IO_DELAY_TYPE
232 default IO_DELAY_TYPE_0X80
236 config DEFAULT_IO_DELAY_TYPE
238 default IO_DELAY_TYPE_0XED
242 config DEFAULT_IO_DELAY_TYPE
244 default IO_DELAY_TYPE_UDELAY
248 config DEFAULT_IO_DELAY_TYPE
250 default IO_DELAY_TYPE_NONE
253 config DEBUG_BOOT_PARAMS
254 bool "Debug boot parameters"
255 depends on DEBUG_KERNEL
258 This option will cause struct boot_params to be exported via debugfs.
261 bool "CPA self-test code"
262 depends on DEBUG_KERNEL
264 Do change_page_attr() self-tests every 30 seconds.
266 config OPTIMIZE_INLINING
267 bool "Allow gcc to uninline functions marked 'inline'"
270 This option determines if the kernel forces gcc to inline the functions
271 developers have marked 'inline'. Doing so takes away freedom from gcc to
272 do what it thinks is best, which is desirable for the gcc 3.x series of
273 compilers. The gcc 4.x series have a rewritten inlining algorithm and
274 disabling this option will generate a smaller kernel there. Hopefully
275 this algorithm is so good that allowing gcc4 to make the decision can
276 become the default in the future, until then this option is there to