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_DBGP
47 bool "Early printk via EHCI debug port"
49 depends on EARLY_PRINTK && PCI
51 Write kernel log output directly into the EHCI debug port.
53 This is useful for kernel debugging when your machine crashes very
54 early before the console code is initialized. For normal operation
55 it is not recommended because it looks ugly and doesn't cooperate
56 with klogd/syslogd or the X server. You should normally N here,
57 unless you want to debug such a crash. You need usb debug device.
59 config DEBUG_STACKOVERFLOW
60 bool "Check for stack overflows"
61 depends on DEBUG_KERNEL
63 This option will cause messages to be printed if free stack space
64 drops below a certain limit.
66 config DEBUG_STACK_USAGE
67 bool "Stack utilization instrumentation"
68 depends on DEBUG_KERNEL
70 Enables the display of the minimum amount of free stack which each
71 task has ever had available in the sysrq-T and sysrq-P debug output.
73 This option will slow down process creation somewhat.
75 config DEBUG_PAGEALLOC
76 bool "Debug page memory allocations"
77 depends on DEBUG_KERNEL
79 Unmap pages from the kernel linear mapping after free_pages().
80 This results in a large slowdown, but helps to find certain types
81 of memory corruptions.
83 config DEBUG_PER_CPU_MAPS
84 bool "Debug access to per_cpu maps"
85 depends on DEBUG_KERNEL
89 Say Y to verify that the per_cpu map being accessed has
90 been setup. Adds a fair amount of code to kernel memory
91 and decreases performance.
96 bool "Export kernel pagetable layout to userspace via debugfs"
97 depends on DEBUG_KERNEL
100 Say Y here if you want to show the kernel pagetable layout in a
101 debugfs file. This information is only useful for kernel developers
102 who are working in architecture specific areas of the kernel.
103 It is probably not a good idea to enable this feature in a production
108 bool "Write protect kernel read-only data structures"
110 depends on DEBUG_KERNEL
112 Mark the kernel read-only data as write-protected in the pagetables,
113 in order to catch accidental (and incorrect) writes to such const
114 data. This is recommended so that we can catch kernel bugs sooner.
115 If in doubt, say "Y".
117 config DIRECT_GBPAGES
118 bool "Enable gbpages-mapped kernel pagetables"
119 depends on DEBUG_KERNEL && EXPERIMENTAL && X86_64
121 Enable gigabyte pages support (if the CPU supports it). This can
122 improve the kernel's performance a tiny bit by reducing TLB
125 This is experimental code.
127 If in doubt, say "N".
129 config DEBUG_RODATA_TEST
130 bool "Testcase for the DEBUG_RODATA feature"
131 depends on DEBUG_RODATA
134 This option enables a testcase for the DEBUG_RODATA
135 feature as well as for the change_page_attr() infrastructure.
139 tristate "Testcase for the NX non-executable stack feature"
140 depends on DEBUG_KERNEL && m
142 This option enables a testcase for the CPU NX capability
143 and the software setup of this feature.
147 bool "Use 4Kb for kernel stacks instead of 8Kb"
150 If you say Y here the kernel will use a 4Kb stacksize for the
151 kernel stack attached to each process/thread. This facilitates
152 running more threads on a system and also reduces the pressure
153 on the VM subsystem for higher order allocations. This option
154 will also use IRQ stacks to compensate for the reduced stackspace.
158 bool "Enable doublefault exception handler" if EMBEDDED
161 This option allows trapping of rare doublefault exceptions that
162 would otherwise cause a system to silently reboot. Disabling this
163 option saves about 4k and might cause you much additional grey
167 bool "Enable IOMMU debugging"
168 depends on GART_IOMMU && DEBUG_KERNEL
171 Force the IOMMU to on even when you have less than 4GB of
172 memory and add debugging code. On overflow always panic. And
173 allow to enable IOMMU leak tracing. Can be disabled at boot
174 time with iommu=noforce. This will also enable scatter gather
175 list merging. Currently not recommended for production
176 code. When you use it make sure you have a big enough
177 IOMMU/AGP aperture. Most of the options enabled by this can
178 be set more finegrained using the iommu= command line
179 options. See Documentation/x86_64/boot-options.txt for more
183 bool "IOMMU leak tracing"
184 depends on DEBUG_KERNEL
185 depends on IOMMU_DEBUG
187 Add a simple leak tracer to the IOMMU code. This is useful when you
188 are debugging a buggy device driver that leaks IOMMU mappings.
190 config MMIOTRACE_HOOKS
194 bool "Memory mapped IO tracing"
195 depends on DEBUG_KERNEL && PCI
197 select MMIOTRACE_HOOKS
199 Mmiotrace traces Memory Mapped I/O access and is meant for
200 debugging and reverse engineering. It is called from the ioremap
201 implementation and works via page faults. Tracing is disabled by
202 default and can be enabled at run-time.
204 See Documentation/tracers/mmiotrace.txt.
205 If you are not helping to develop drivers, say N.
207 config MMIOTRACE_TEST
208 tristate "Test module for mmiotrace"
209 depends on MMIOTRACE && m
211 This is a dumb module for testing mmiotrace. It is very dangerous
212 as it will write garbage to IO memory starting at a given address.
213 However, it should be safe to use on e.g. unused portion of VRAM.
215 Say N, unless you absolutely know what you are doing.
221 config IO_DELAY_TYPE_0X80
225 config IO_DELAY_TYPE_0XED
229 config IO_DELAY_TYPE_UDELAY
233 config IO_DELAY_TYPE_NONE
238 prompt "IO delay type"
239 default IO_DELAY_0X80
242 bool "port 0x80 based port-IO delay [recommended]"
244 This is the traditional Linux IO delay used for in/out_p.
245 It is the most tested hence safest selection here.
248 bool "port 0xed based port-IO delay"
250 Use port 0xed as the IO delay. This frees up port 0x80 which is
251 often used as a hardware-debug port.
253 config IO_DELAY_UDELAY
254 bool "udelay based port-IO delay"
256 Use udelay(2) as the IO delay method. This provides the delay
257 while not having any side-effect on the IO port space.
260 bool "no port-IO delay"
262 No port-IO delay. Will break on old boxes that require port-IO
263 delay for certain operations. Should work on most new machines.
268 config DEFAULT_IO_DELAY_TYPE
270 default IO_DELAY_TYPE_0X80
274 config DEFAULT_IO_DELAY_TYPE
276 default IO_DELAY_TYPE_0XED
280 config DEFAULT_IO_DELAY_TYPE
282 default IO_DELAY_TYPE_UDELAY
286 config DEFAULT_IO_DELAY_TYPE
288 default IO_DELAY_TYPE_NONE
291 config DEBUG_BOOT_PARAMS
292 bool "Debug boot parameters"
293 depends on DEBUG_KERNEL
296 This option will cause struct boot_params to be exported via debugfs.
299 bool "CPA self-test code"
300 depends on DEBUG_KERNEL
302 Do change_page_attr() self-tests every 30 seconds.
304 config OPTIMIZE_INLINING
305 bool "Allow gcc to uninline functions marked 'inline'"
307 This option determines if the kernel forces gcc to inline the functions
308 developers have marked 'inline'. Doing so takes away freedom from gcc to
309 do what it thinks is best, which is desirable for the gcc 3.x series of
310 compilers. The gcc 4.x series have a rewritten inlining algorithm and
311 disabling this option will generate a smaller kernel there. Hopefully
312 this algorithm is so good that allowing gcc4 to make the decision can
313 become the default in the future, until then this option is there to