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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 |
6a108a14 | 34 | bool "Early printk" if EXPERT |
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 | ||
1ea7c673 AC |
46 | config EARLY_PRINTK_INTEL_MID |
47 | bool "Early printk for Intel MID platform support" | |
48 | depends on EARLY_PRINTK && X86_INTEL_MID | |
c20b5c33 | 49 | |
5c05917e YL |
50 | config EARLY_PRINTK_DBGP |
51 | bool "Early printk via EHCI debug port" | |
9749986a | 52 | depends on EARLY_PRINTK && PCI |
8f9ca475 | 53 | ---help--- |
5c05917e YL |
54 | Write kernel log output directly into the EHCI debug port. |
55 | ||
56 | This is useful for kernel debugging when your machine crashes very | |
57 | early before the console code is initialized. For normal operation | |
58 | it is not recommended because it looks ugly and doesn't cooperate | |
59 | with klogd/syslogd or the X server. You should normally N here, | |
60 | unless you want to debug such a crash. You need usb debug device. | |
61 | ||
926e5392 AV |
62 | config X86_PTDUMP |
63 | bool "Export kernel pagetable layout to userspace via debugfs" | |
fe770bf0 | 64 | depends on DEBUG_KERNEL |
926e5392 | 65 | select DEBUG_FS |
8f9ca475 | 66 | ---help--- |
926e5392 AV |
67 | Say Y here if you want to show the kernel pagetable layout in a |
68 | debugfs file. This information is only useful for kernel developers | |
69 | who are working in architecture specific areas of the kernel. | |
70 | It is probably not a good idea to enable this feature in a production | |
71 | kernel. | |
72 | If in doubt, say "N" | |
73 | ||
63aaf308 AV |
74 | config DEBUG_RODATA |
75 | bool "Write protect kernel read-only data structures" | |
11201e60 | 76 | default y |
63aaf308 | 77 | depends on DEBUG_KERNEL |
8f9ca475 | 78 | ---help--- |
63aaf308 AV |
79 | Mark the kernel read-only data as write-protected in the pagetables, |
80 | in order to catch accidental (and incorrect) writes to such const | |
11201e60 IM |
81 | data. This is recommended so that we can catch kernel bugs sooner. |
82 | If in doubt, say "Y". | |
63aaf308 | 83 | |
aba8391f IM |
84 | config DEBUG_RODATA_TEST |
85 | bool "Testcase for the DEBUG_RODATA feature" | |
86 | depends on DEBUG_RODATA | |
72370f2a | 87 | default y |
8f9ca475 | 88 | ---help--- |
aba8391f IM |
89 | This option enables a testcase for the DEBUG_RODATA |
90 | feature as well as for the change_page_attr() infrastructure. | |
91 | If in doubt, say "N" | |
92 | ||
84e1c6bb MC |
93 | config DEBUG_SET_MODULE_RONX |
94 | bool "Set loadable kernel module data as NX and text as RO" | |
95 | depends on MODULES | |
96 | ---help--- | |
97 | This option helps catch unintended modifications to loadable | |
98 | kernel module's text and read-only data. It also prevents execution | |
99 | of module data. Such protection may interfere with run-time code | |
100 | patching and dynamic kernel tracing - and they might also protect | |
101 | against certain classes of kernel exploits. | |
102 | If in doubt, say "N". | |
103 | ||
aba8391f IM |
104 | config DEBUG_NX_TEST |
105 | tristate "Testcase for the NX non-executable stack feature" | |
106 | depends on DEBUG_KERNEL && m | |
8f9ca475 | 107 | ---help--- |
aba8391f IM |
108 | This option enables a testcase for the CPU NX capability |
109 | and the software setup of this feature. | |
110 | If in doubt, say "N" | |
111 | ||
102e41fd AK |
112 | config DOUBLEFAULT |
113 | default y | |
6a108a14 | 114 | bool "Enable doublefault exception handler" if EXPERT |
8f9ca475 | 115 | ---help--- |
d013a27c RD |
116 | This option allows trapping of rare doublefault exceptions that |
117 | would otherwise cause a system to silently reboot. Disabling this | |
118 | option saves about 4k and might cause you much additional grey | |
119 | hair. | |
120 | ||
3df3212f AS |
121 | config DEBUG_TLBFLUSH |
122 | bool "Set upper limit of TLB entries to flush one-by-one" | |
cd69aa6b | 123 | depends on DEBUG_KERNEL |
3df3212f AS |
124 | ---help--- |
125 | ||
126 | X86-only for now. | |
127 | ||
128 | This option allows the user to tune the amount of TLB entries the | |
129 | kernel flushes one-by-one instead of doing a full TLB flush. In | |
130 | certain situations, the former is cheaper. This is controlled by the | |
131 | tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it | |
132 | to -1, the code flushes the whole TLB unconditionally. Otherwise, | |
133 | for positive values of it, the kernel will use single TLB entry | |
134 | invalidating instructions according to the following formula: | |
135 | ||
136 | flush_entries <= active_tlb_entries / 2^tlb_flushall_shift | |
137 | ||
138 | If in doubt, say "N". | |
139 | ||
d013a27c RD |
140 | config IOMMU_DEBUG |
141 | bool "Enable IOMMU debugging" | |
966396d3 | 142 | depends on GART_IOMMU && DEBUG_KERNEL |
d013a27c | 143 | depends on X86_64 |
8f9ca475 | 144 | ---help--- |
d013a27c RD |
145 | Force the IOMMU to on even when you have less than 4GB of |
146 | memory and add debugging code. On overflow always panic. And | |
147 | allow to enable IOMMU leak tracing. Can be disabled at boot | |
148 | time with iommu=noforce. This will also enable scatter gather | |
149 | list merging. Currently not recommended for production | |
150 | code. When you use it make sure you have a big enough | |
151 | IOMMU/AGP aperture. Most of the options enabled by this can | |
152 | be set more finegrained using the iommu= command line | |
395cf969 | 153 | options. See Documentation/x86/x86_64/boot-options.txt for more |
d013a27c RD |
154 | details. |
155 | ||
2be69c79 JR |
156 | config IOMMU_STRESS |
157 | bool "Enable IOMMU stress-test mode" | |
158 | ---help--- | |
159 | This option disables various optimizations in IOMMU related | |
160 | code to do real stress testing of the IOMMU code. This option | |
161 | will cause a performance drop and should only be enabled for | |
162 | testing. | |
163 | ||
d013a27c RD |
164 | config IOMMU_LEAK |
165 | bool "IOMMU leak tracing" | |
19c1a6f5 | 166 | depends on IOMMU_DEBUG && DMA_API_DEBUG |
8f9ca475 | 167 | ---help--- |
d013a27c RD |
168 | Add a simple leak tracer to the IOMMU code. This is useful when you |
169 | are debugging a buggy device driver that leaks IOMMU mappings. | |
170 | ||
6bc5c366 PP |
171 | config HAVE_MMIOTRACE_SUPPORT |
172 | def_bool y | |
8b7d89d0 | 173 | |
ca0e9bad | 174 | config X86_DECODER_SELFTEST |
cbe5c34c OH |
175 | bool "x86 instruction decoder selftest" |
176 | depends on DEBUG_KERNEL && KPROBES | |
ca0e9bad MH |
177 | ---help--- |
178 | Perform x86 instruction decoder selftests at build time. | |
179 | This option is useful for checking the sanity of x86 instruction | |
180 | decoder code. | |
181 | If unsure, say "N". | |
182 | ||
6e7c4025 IM |
183 | # |
184 | # IO delay types: | |
185 | # | |
186 | ||
187 | config IO_DELAY_TYPE_0X80 | |
188 | int | |
189 | default "0" | |
190 | ||
191 | config IO_DELAY_TYPE_0XED | |
192 | int | |
193 | default "1" | |
194 | ||
195 | config IO_DELAY_TYPE_UDELAY | |
196 | int | |
197 | default "2" | |
198 | ||
199 | config IO_DELAY_TYPE_NONE | |
200 | int | |
201 | default "3" | |
202 | ||
203 | choice | |
204 | prompt "IO delay type" | |
fd59e9e9 | 205 | default IO_DELAY_0X80 |
6e7c4025 IM |
206 | |
207 | config IO_DELAY_0X80 | |
208 | bool "port 0x80 based port-IO delay [recommended]" | |
8f9ca475 | 209 | ---help--- |
6e7c4025 IM |
210 | This is the traditional Linux IO delay used for in/out_p. |
211 | It is the most tested hence safest selection here. | |
212 | ||
213 | config IO_DELAY_0XED | |
214 | bool "port 0xed based port-IO delay" | |
8f9ca475 | 215 | ---help--- |
6e7c4025 IM |
216 | Use port 0xed as the IO delay. This frees up port 0x80 which is |
217 | often used as a hardware-debug port. | |
218 | ||
219 | config IO_DELAY_UDELAY | |
220 | bool "udelay based port-IO delay" | |
8f9ca475 | 221 | ---help--- |
6e7c4025 IM |
222 | Use udelay(2) as the IO delay method. This provides the delay |
223 | while not having any side-effect on the IO port space. | |
224 | ||
225 | config IO_DELAY_NONE | |
226 | bool "no port-IO delay" | |
8f9ca475 | 227 | ---help--- |
6e7c4025 IM |
228 | No port-IO delay. Will break on old boxes that require port-IO |
229 | delay for certain operations. Should work on most new machines. | |
230 | ||
231 | endchoice | |
232 | ||
233 | if IO_DELAY_0X80 | |
234 | config DEFAULT_IO_DELAY_TYPE | |
235 | int | |
236 | default IO_DELAY_TYPE_0X80 | |
237 | endif | |
238 | ||
239 | if IO_DELAY_0XED | |
240 | config DEFAULT_IO_DELAY_TYPE | |
241 | int | |
242 | default IO_DELAY_TYPE_0XED | |
243 | endif | |
244 | ||
245 | if IO_DELAY_UDELAY | |
246 | config DEFAULT_IO_DELAY_TYPE | |
247 | int | |
248 | default IO_DELAY_TYPE_UDELAY | |
249 | endif | |
250 | ||
251 | if IO_DELAY_NONE | |
252 | config DEFAULT_IO_DELAY_TYPE | |
253 | int | |
254 | default IO_DELAY_TYPE_NONE | |
255 | endif | |
b02aae9c | 256 | |
6d7d7433 HY |
257 | config DEBUG_BOOT_PARAMS |
258 | bool "Debug boot parameters" | |
259 | depends on DEBUG_KERNEL | |
260 | depends on DEBUG_FS | |
8f9ca475 | 261 | ---help--- |
6d7d7433 HY |
262 | This option will cause struct boot_params to be exported via debugfs. |
263 | ||
0c42f392 | 264 | config CPA_DEBUG |
971a52d6 | 265 | bool "CPA self-test code" |
f316fe68 | 266 | depends on DEBUG_KERNEL |
8f9ca475 | 267 | ---help--- |
971a52d6 | 268 | Do change_page_attr() self-tests every 30 seconds. |
0c42f392 | 269 | |
60a3cdd0 IM |
270 | config OPTIMIZE_INLINING |
271 | bool "Allow gcc to uninline functions marked 'inline'" | |
8f9ca475 | 272 | ---help--- |
60a3cdd0 IM |
273 | This option determines if the kernel forces gcc to inline the functions |
274 | developers have marked 'inline'. Doing so takes away freedom from gcc to | |
275 | do what it thinks is best, which is desirable for the gcc 3.x series of | |
276 | compilers. The gcc 4.x series have a rewritten inlining algorithm and | |
63fb7085 SW |
277 | enabling this option will generate a smaller kernel there. Hopefully |
278 | this algorithm is so good that allowing gcc 4.x and above to make the | |
279 | decision will become the default in the future. Until then this option | |
280 | is there to test gcc for this. | |
c9af1e33 | 281 | |
3f9b5cc0 IM |
282 | If unsure, say N. |
283 | ||
99e8b9ca DZ |
284 | config DEBUG_NMI_SELFTEST |
285 | bool "NMI Selftest" | |
4f941c57 | 286 | depends on DEBUG_KERNEL && X86_LOCAL_APIC |
99e8b9ca DZ |
287 | ---help--- |
288 | Enabling this option turns on a quick NMI selftest to verify | |
289 | that the NMI behaves correctly. | |
290 | ||
291 | This might help diagnose strange hangs that rely on NMI to | |
292 | function properly. | |
293 | ||
294 | If unsure, say N. | |
295 | ||
5700f743 BP |
296 | config X86_DEBUG_STATIC_CPU_HAS |
297 | bool "Debug alternatives" | |
298 | depends on DEBUG_KERNEL | |
299 | ---help--- | |
300 | This option causes additional code to be generated which | |
301 | fails if static_cpu_has() is used before alternatives have | |
302 | run. | |
303 | ||
304 | If unsure, say N. | |
305 | ||
c9af1e33 | 306 | endmenu |