Commit | Line | Data |
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1da177e4 LT |
1 | menu "Kernel hacking" |
2 | ||
55f327fa | 3 | config TRACE_IRQFLAGS_SUPPORT |
d013a27c | 4 | def_bool y |
55f327fa | 5 | |
1da177e4 LT |
6 | source "lib/Kconfig.debug" |
7 | ||
d092633b | 8 | config STRICT_DEVMEM |
16104b55 | 9 | bool "Filter access to /dev/mem" |
8f9ca475 | 10 | ---help--- |
f2d0f1de | 11 | If this option is disabled, you allow userspace (root) access to all |
16104b55 SR |
12 | of memory, including kernel and userspace memory. Accidental |
13 | access to this is obviously disastrous, but specific access can | |
d092633b IM |
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. | |
16104b55 SR |
17 | |
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 | |
21 | /dev/mem. | |
22 | ||
23 | If in doubt, say Y. | |
ae531c26 | 24 | |
6bcb13b3 BC |
25 | config X86_VERBOSE_BOOTUP |
26 | bool "Enable verbose x86 bootup info messages" | |
27 | default y | |
8f9ca475 | 28 | ---help--- |
6bcb13b3 BC |
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. | |
32 | ||
1da177e4 | 33 | config EARLY_PRINTK |
076f9776 | 34 | bool "Early printk" if EMBEDDED |
1da177e4 | 35 | default y |
8f9ca475 | 36 | ---help--- |
1da177e4 LT |
37 | Write kernel log output directly into the VGA buffer or to a serial |
38 | port. | |
39 | ||
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. | |
45 | ||
5c05917e YL |
46 | config EARLY_PRINTK_DBGP |
47 | bool "Early printk via EHCI debug port" | |
9749986a | 48 | depends on EARLY_PRINTK && PCI |
8f9ca475 | 49 | ---help--- |
5c05917e YL |
50 | Write kernel log output directly into the EHCI debug port. |
51 | ||
52 | This is useful for kernel debugging when your machine crashes very | |
53 | early before the console code is initialized. For normal operation | |
54 | it is not recommended because it looks ugly and doesn't cooperate | |
55 | with klogd/syslogd or the X server. You should normally N here, | |
56 | unless you want to debug such a crash. You need usb debug device. | |
57 | ||
1da177e4 LT |
58 | config DEBUG_STACKOVERFLOW |
59 | bool "Check for stack overflows" | |
60 | depends on DEBUG_KERNEL | |
8f9ca475 | 61 | ---help--- |
dab175f3 AB |
62 | This option will cause messages to be printed if free stack space |
63 | drops below a certain limit. | |
1da177e4 | 64 | |
1da177e4 LT |
65 | config DEBUG_STACK_USAGE |
66 | bool "Stack utilization instrumentation" | |
67 | depends on DEBUG_KERNEL | |
8f9ca475 | 68 | ---help--- |
1da177e4 LT |
69 | Enables the display of the minimum amount of free stack which each |
70 | task has ever had available in the sysrq-T and sysrq-P debug output. | |
71 | ||
72 | This option will slow down process creation somewhat. | |
73 | ||
c49a4955 | 74 | config DEBUG_PER_CPU_MAPS |
75 | bool "Debug access to per_cpu maps" | |
76 | depends on DEBUG_KERNEL | |
3e5095d1 | 77 | depends on SMP |
8f9ca475 | 78 | ---help--- |
c49a4955 | 79 | Say Y to verify that the per_cpu map being accessed has |
80 | been setup. Adds a fair amount of code to kernel memory | |
81 | and decreases performance. | |
82 | ||
83 | Say N if unsure. | |
84 | ||
926e5392 AV |
85 | config X86_PTDUMP |
86 | bool "Export kernel pagetable layout to userspace via debugfs" | |
fe770bf0 | 87 | depends on DEBUG_KERNEL |
926e5392 | 88 | select DEBUG_FS |
8f9ca475 | 89 | ---help--- |
926e5392 AV |
90 | Say Y here if you want to show the kernel pagetable layout in a |
91 | debugfs file. This information is only useful for kernel developers | |
92 | who are working in architecture specific areas of the kernel. | |
93 | It is probably not a good idea to enable this feature in a production | |
94 | kernel. | |
95 | If in doubt, say "N" | |
96 | ||
63aaf308 AV |
97 | config DEBUG_RODATA |
98 | bool "Write protect kernel read-only data structures" | |
11201e60 | 99 | default y |
63aaf308 | 100 | depends on DEBUG_KERNEL |
8f9ca475 | 101 | ---help--- |
63aaf308 AV |
102 | Mark the kernel read-only data as write-protected in the pagetables, |
103 | in order to catch accidental (and incorrect) writes to such const | |
11201e60 IM |
104 | data. This is recommended so that we can catch kernel bugs sooner. |
105 | If in doubt, say "Y". | |
63aaf308 | 106 | |
aba8391f IM |
107 | config DEBUG_RODATA_TEST |
108 | bool "Testcase for the DEBUG_RODATA feature" | |
109 | depends on DEBUG_RODATA | |
72370f2a | 110 | default y |
8f9ca475 | 111 | ---help--- |
aba8391f IM |
112 | This option enables a testcase for the DEBUG_RODATA |
113 | feature as well as for the change_page_attr() infrastructure. | |
114 | If in doubt, say "N" | |
115 | ||
116 | config DEBUG_NX_TEST | |
117 | tristate "Testcase for the NX non-executable stack feature" | |
118 | depends on DEBUG_KERNEL && m | |
8f9ca475 | 119 | ---help--- |
aba8391f IM |
120 | This option enables a testcase for the CPU NX capability |
121 | and the software setup of this feature. | |
122 | If in doubt, say "N" | |
123 | ||
1da177e4 LT |
124 | config 4KSTACKS |
125 | bool "Use 4Kb for kernel stacks instead of 8Kb" | |
d013a27c | 126 | depends on X86_32 |
8f9ca475 | 127 | ---help--- |
1da177e4 LT |
128 | If you say Y here the kernel will use a 4Kb stacksize for the |
129 | kernel stack attached to each process/thread. This facilitates | |
130 | running more threads on a system and also reduces the pressure | |
131 | on the VM subsystem for higher order allocations. This option | |
132 | will also use IRQ stacks to compensate for the reduced stackspace. | |
133 | ||
102e41fd AK |
134 | config DOUBLEFAULT |
135 | default y | |
136 | bool "Enable doublefault exception handler" if EMBEDDED | |
d013a27c | 137 | depends on X86_32 |
8f9ca475 | 138 | ---help--- |
d013a27c RD |
139 | This option allows trapping of rare doublefault exceptions that |
140 | would otherwise cause a system to silently reboot. Disabling this | |
141 | option saves about 4k and might cause you much additional grey | |
142 | hair. | |
143 | ||
144 | config IOMMU_DEBUG | |
145 | bool "Enable IOMMU debugging" | |
966396d3 | 146 | depends on GART_IOMMU && DEBUG_KERNEL |
d013a27c | 147 | depends on X86_64 |
8f9ca475 | 148 | ---help--- |
d013a27c RD |
149 | Force the IOMMU to on even when you have less than 4GB of |
150 | memory and add debugging code. On overflow always panic. And | |
151 | allow to enable IOMMU leak tracing. Can be disabled at boot | |
152 | time with iommu=noforce. This will also enable scatter gather | |
153 | list merging. Currently not recommended for production | |
154 | code. When you use it make sure you have a big enough | |
155 | IOMMU/AGP aperture. Most of the options enabled by this can | |
156 | be set more finegrained using the iommu= command line | |
157 | options. See Documentation/x86_64/boot-options.txt for more | |
158 | details. | |
159 | ||
2be69c79 JR |
160 | config IOMMU_STRESS |
161 | bool "Enable IOMMU stress-test mode" | |
162 | ---help--- | |
163 | This option disables various optimizations in IOMMU related | |
164 | code to do real stress testing of the IOMMU code. This option | |
165 | will cause a performance drop and should only be enabled for | |
166 | testing. | |
167 | ||
d013a27c RD |
168 | config IOMMU_LEAK |
169 | bool "IOMMU leak tracing" | |
19c1a6f5 | 170 | depends on IOMMU_DEBUG && DMA_API_DEBUG |
8f9ca475 | 171 | ---help--- |
d013a27c RD |
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. | |
174 | ||
6bc5c366 PP |
175 | config HAVE_MMIOTRACE_SUPPORT |
176 | def_bool y | |
8b7d89d0 | 177 | |
ca0e9bad | 178 | config X86_DECODER_SELFTEST |
cbe5c34c OH |
179 | bool "x86 instruction decoder selftest" |
180 | depends on DEBUG_KERNEL && KPROBES | |
ca0e9bad MH |
181 | ---help--- |
182 | Perform x86 instruction decoder selftests at build time. | |
183 | This option is useful for checking the sanity of x86 instruction | |
184 | decoder code. | |
185 | If unsure, say "N". | |
186 | ||
6e7c4025 IM |
187 | # |
188 | # IO delay types: | |
189 | # | |
190 | ||
191 | config IO_DELAY_TYPE_0X80 | |
192 | int | |
193 | default "0" | |
194 | ||
195 | config IO_DELAY_TYPE_0XED | |
196 | int | |
197 | default "1" | |
198 | ||
199 | config IO_DELAY_TYPE_UDELAY | |
200 | int | |
201 | default "2" | |
202 | ||
203 | config IO_DELAY_TYPE_NONE | |
204 | int | |
205 | default "3" | |
206 | ||
207 | choice | |
208 | prompt "IO delay type" | |
fd59e9e9 | 209 | default IO_DELAY_0X80 |
6e7c4025 IM |
210 | |
211 | config IO_DELAY_0X80 | |
212 | bool "port 0x80 based port-IO delay [recommended]" | |
8f9ca475 | 213 | ---help--- |
6e7c4025 IM |
214 | This is the traditional Linux IO delay used for in/out_p. |
215 | It is the most tested hence safest selection here. | |
216 | ||
217 | config IO_DELAY_0XED | |
218 | bool "port 0xed based port-IO delay" | |
8f9ca475 | 219 | ---help--- |
6e7c4025 IM |
220 | Use port 0xed as the IO delay. This frees up port 0x80 which is |
221 | often used as a hardware-debug port. | |
222 | ||
223 | config IO_DELAY_UDELAY | |
224 | bool "udelay based port-IO delay" | |
8f9ca475 | 225 | ---help--- |
6e7c4025 IM |
226 | Use udelay(2) as the IO delay method. This provides the delay |
227 | while not having any side-effect on the IO port space. | |
228 | ||
229 | config IO_DELAY_NONE | |
230 | bool "no port-IO delay" | |
8f9ca475 | 231 | ---help--- |
6e7c4025 IM |
232 | No port-IO delay. Will break on old boxes that require port-IO |
233 | delay for certain operations. Should work on most new machines. | |
234 | ||
235 | endchoice | |
236 | ||
237 | if IO_DELAY_0X80 | |
238 | config DEFAULT_IO_DELAY_TYPE | |
239 | int | |
240 | default IO_DELAY_TYPE_0X80 | |
241 | endif | |
242 | ||
243 | if IO_DELAY_0XED | |
244 | config DEFAULT_IO_DELAY_TYPE | |
245 | int | |
246 | default IO_DELAY_TYPE_0XED | |
247 | endif | |
248 | ||
249 | if IO_DELAY_UDELAY | |
250 | config DEFAULT_IO_DELAY_TYPE | |
251 | int | |
252 | default IO_DELAY_TYPE_UDELAY | |
253 | endif | |
254 | ||
255 | if IO_DELAY_NONE | |
256 | config DEFAULT_IO_DELAY_TYPE | |
257 | int | |
258 | default IO_DELAY_TYPE_NONE | |
259 | endif | |
b02aae9c | 260 | |
6d7d7433 HY |
261 | config DEBUG_BOOT_PARAMS |
262 | bool "Debug boot parameters" | |
263 | depends on DEBUG_KERNEL | |
264 | depends on DEBUG_FS | |
8f9ca475 | 265 | ---help--- |
6d7d7433 HY |
266 | This option will cause struct boot_params to be exported via debugfs. |
267 | ||
0c42f392 | 268 | config CPA_DEBUG |
971a52d6 | 269 | bool "CPA self-test code" |
f316fe68 | 270 | depends on DEBUG_KERNEL |
8f9ca475 | 271 | ---help--- |
971a52d6 | 272 | Do change_page_attr() self-tests every 30 seconds. |
0c42f392 | 273 | |
60a3cdd0 IM |
274 | config OPTIMIZE_INLINING |
275 | bool "Allow gcc to uninline functions marked 'inline'" | |
8f9ca475 | 276 | ---help--- |
60a3cdd0 IM |
277 | This option determines if the kernel forces gcc to inline the functions |
278 | developers have marked 'inline'. Doing so takes away freedom from gcc to | |
279 | do what it thinks is best, which is desirable for the gcc 3.x series of | |
280 | compilers. The gcc 4.x series have a rewritten inlining algorithm and | |
63fb7085 SW |
281 | enabling this option will generate a smaller kernel there. Hopefully |
282 | this algorithm is so good that allowing gcc 4.x and above to make the | |
283 | decision will become the default in the future. Until then this option | |
284 | is there to test gcc for this. | |
c9af1e33 | 285 | |
3f9b5cc0 IM |
286 | If unsure, say N. |
287 | ||
63312b6a AV |
288 | config DEBUG_STRICT_USER_COPY_CHECKS |
289 | bool "Strict copy size checks" | |
ad8f4356 | 290 | depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING |
63312b6a AV |
291 | ---help--- |
292 | Enabling this option turns a certain set of sanity checks for user | |
293 | copy operations into compile time failures. | |
294 | ||
295 | The copy_from_user() etc checks are there to help test if there | |
296 | are sufficient security checks on the length argument of | |
297 | the copy operation, by having gcc prove that the argument is | |
298 | within bounds. | |
299 | ||
300 | If unsure, or if you run an older (pre 4.4) gcc, say N. | |
301 | ||
c9af1e33 | 302 | endmenu |