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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 |
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 | ||
72548e83 MF |
62 | config EARLY_PRINTK_EFI |
63 | bool "Early printk via the EFI framebuffer" | |
64 | depends on EFI && EARLY_PRINTK | |
65 | select FONT_SUPPORT | |
66 | ---help--- | |
67 | Write kernel log output directly into the EFI framebuffer. | |
68 | ||
69 | This is useful for kernel debugging when your machine crashes very | |
70 | early before the console code is initialized. | |
71 | ||
926e5392 AV |
72 | config X86_PTDUMP |
73 | bool "Export kernel pagetable layout to userspace via debugfs" | |
fe770bf0 | 74 | depends on DEBUG_KERNEL |
926e5392 | 75 | select DEBUG_FS |
8f9ca475 | 76 | ---help--- |
926e5392 AV |
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 | |
81 | kernel. | |
82 | If in doubt, say "N" | |
83 | ||
63aaf308 AV |
84 | config DEBUG_RODATA |
85 | bool "Write protect kernel read-only data structures" | |
11201e60 | 86 | default y |
63aaf308 | 87 | depends on DEBUG_KERNEL |
8f9ca475 | 88 | ---help--- |
63aaf308 AV |
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 | |
11201e60 IM |
91 | data. This is recommended so that we can catch kernel bugs sooner. |
92 | If in doubt, say "Y". | |
63aaf308 | 93 | |
aba8391f IM |
94 | config DEBUG_RODATA_TEST |
95 | bool "Testcase for the DEBUG_RODATA feature" | |
96 | depends on DEBUG_RODATA | |
72370f2a | 97 | default y |
8f9ca475 | 98 | ---help--- |
aba8391f IM |
99 | This option enables a testcase for the DEBUG_RODATA |
100 | feature as well as for the change_page_attr() infrastructure. | |
101 | If in doubt, say "N" | |
102 | ||
84e1c6bb MC |
103 | config DEBUG_SET_MODULE_RONX |
104 | bool "Set loadable kernel module data as NX and text as RO" | |
105 | depends on MODULES | |
106 | ---help--- | |
107 | This option helps catch unintended modifications to loadable | |
108 | kernel module's text and read-only data. It also prevents execution | |
109 | of module data. Such protection may interfere with run-time code | |
110 | patching and dynamic kernel tracing - and they might also protect | |
111 | against certain classes of kernel exploits. | |
112 | If in doubt, say "N". | |
113 | ||
aba8391f IM |
114 | config DEBUG_NX_TEST |
115 | tristate "Testcase for the NX non-executable stack feature" | |
116 | depends on DEBUG_KERNEL && m | |
8f9ca475 | 117 | ---help--- |
aba8391f IM |
118 | This option enables a testcase for the CPU NX capability |
119 | and the software setup of this feature. | |
120 | If in doubt, say "N" | |
121 | ||
102e41fd AK |
122 | config DOUBLEFAULT |
123 | default y | |
6a108a14 | 124 | bool "Enable doublefault exception handler" if EXPERT |
8f9ca475 | 125 | ---help--- |
d013a27c RD |
126 | This option allows trapping of rare doublefault exceptions that |
127 | would otherwise cause a system to silently reboot. Disabling this | |
128 | option saves about 4k and might cause you much additional grey | |
129 | hair. | |
130 | ||
3df3212f AS |
131 | config DEBUG_TLBFLUSH |
132 | bool "Set upper limit of TLB entries to flush one-by-one" | |
cd69aa6b | 133 | depends on DEBUG_KERNEL |
3df3212f AS |
134 | ---help--- |
135 | ||
136 | X86-only for now. | |
137 | ||
138 | This option allows the user to tune the amount of TLB entries the | |
139 | kernel flushes one-by-one instead of doing a full TLB flush. In | |
140 | certain situations, the former is cheaper. This is controlled by the | |
141 | tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it | |
142 | to -1, the code flushes the whole TLB unconditionally. Otherwise, | |
143 | for positive values of it, the kernel will use single TLB entry | |
144 | invalidating instructions according to the following formula: | |
145 | ||
146 | flush_entries <= active_tlb_entries / 2^tlb_flushall_shift | |
147 | ||
148 | If in doubt, say "N". | |
149 | ||
d013a27c RD |
150 | config IOMMU_DEBUG |
151 | bool "Enable IOMMU debugging" | |
966396d3 | 152 | depends on GART_IOMMU && DEBUG_KERNEL |
d013a27c | 153 | depends on X86_64 |
8f9ca475 | 154 | ---help--- |
d013a27c RD |
155 | Force the IOMMU to on even when you have less than 4GB of |
156 | memory and add debugging code. On overflow always panic. And | |
157 | allow to enable IOMMU leak tracing. Can be disabled at boot | |
158 | time with iommu=noforce. This will also enable scatter gather | |
159 | list merging. Currently not recommended for production | |
160 | code. When you use it make sure you have a big enough | |
161 | IOMMU/AGP aperture. Most of the options enabled by this can | |
162 | be set more finegrained using the iommu= command line | |
395cf969 | 163 | options. See Documentation/x86/x86_64/boot-options.txt for more |
d013a27c RD |
164 | details. |
165 | ||
2be69c79 JR |
166 | config IOMMU_STRESS |
167 | bool "Enable IOMMU stress-test mode" | |
168 | ---help--- | |
169 | This option disables various optimizations in IOMMU related | |
170 | code to do real stress testing of the IOMMU code. This option | |
171 | will cause a performance drop and should only be enabled for | |
172 | testing. | |
173 | ||
d013a27c RD |
174 | config IOMMU_LEAK |
175 | bool "IOMMU leak tracing" | |
19c1a6f5 | 176 | depends on IOMMU_DEBUG && DMA_API_DEBUG |
8f9ca475 | 177 | ---help--- |
d013a27c RD |
178 | Add a simple leak tracer to the IOMMU code. This is useful when you |
179 | are debugging a buggy device driver that leaks IOMMU mappings. | |
180 | ||
6bc5c366 PP |
181 | config HAVE_MMIOTRACE_SUPPORT |
182 | def_bool y | |
8b7d89d0 | 183 | |
ca0e9bad | 184 | config X86_DECODER_SELFTEST |
cbe5c34c OH |
185 | bool "x86 instruction decoder selftest" |
186 | depends on DEBUG_KERNEL && KPROBES | |
ca0e9bad MH |
187 | ---help--- |
188 | Perform x86 instruction decoder selftests at build time. | |
189 | This option is useful for checking the sanity of x86 instruction | |
190 | decoder code. | |
191 | If unsure, say "N". | |
192 | ||
6e7c4025 IM |
193 | # |
194 | # IO delay types: | |
195 | # | |
196 | ||
197 | config IO_DELAY_TYPE_0X80 | |
198 | int | |
199 | default "0" | |
200 | ||
201 | config IO_DELAY_TYPE_0XED | |
202 | int | |
203 | default "1" | |
204 | ||
205 | config IO_DELAY_TYPE_UDELAY | |
206 | int | |
207 | default "2" | |
208 | ||
209 | config IO_DELAY_TYPE_NONE | |
210 | int | |
211 | default "3" | |
212 | ||
213 | choice | |
214 | prompt "IO delay type" | |
fd59e9e9 | 215 | default IO_DELAY_0X80 |
6e7c4025 IM |
216 | |
217 | config IO_DELAY_0X80 | |
218 | bool "port 0x80 based port-IO delay [recommended]" | |
8f9ca475 | 219 | ---help--- |
6e7c4025 IM |
220 | This is the traditional Linux IO delay used for in/out_p. |
221 | It is the most tested hence safest selection here. | |
222 | ||
223 | config IO_DELAY_0XED | |
224 | bool "port 0xed based port-IO delay" | |
8f9ca475 | 225 | ---help--- |
6e7c4025 IM |
226 | Use port 0xed as the IO delay. This frees up port 0x80 which is |
227 | often used as a hardware-debug port. | |
228 | ||
229 | config IO_DELAY_UDELAY | |
230 | bool "udelay based port-IO delay" | |
8f9ca475 | 231 | ---help--- |
6e7c4025 IM |
232 | Use udelay(2) as the IO delay method. This provides the delay |
233 | while not having any side-effect on the IO port space. | |
234 | ||
235 | config IO_DELAY_NONE | |
236 | bool "no port-IO delay" | |
8f9ca475 | 237 | ---help--- |
6e7c4025 IM |
238 | No port-IO delay. Will break on old boxes that require port-IO |
239 | delay for certain operations. Should work on most new machines. | |
240 | ||
241 | endchoice | |
242 | ||
243 | if IO_DELAY_0X80 | |
244 | config DEFAULT_IO_DELAY_TYPE | |
245 | int | |
246 | default IO_DELAY_TYPE_0X80 | |
247 | endif | |
248 | ||
249 | if IO_DELAY_0XED | |
250 | config DEFAULT_IO_DELAY_TYPE | |
251 | int | |
252 | default IO_DELAY_TYPE_0XED | |
253 | endif | |
254 | ||
255 | if IO_DELAY_UDELAY | |
256 | config DEFAULT_IO_DELAY_TYPE | |
257 | int | |
258 | default IO_DELAY_TYPE_UDELAY | |
259 | endif | |
260 | ||
261 | if IO_DELAY_NONE | |
262 | config DEFAULT_IO_DELAY_TYPE | |
263 | int | |
264 | default IO_DELAY_TYPE_NONE | |
265 | endif | |
b02aae9c | 266 | |
6d7d7433 HY |
267 | config DEBUG_BOOT_PARAMS |
268 | bool "Debug boot parameters" | |
269 | depends on DEBUG_KERNEL | |
270 | depends on DEBUG_FS | |
8f9ca475 | 271 | ---help--- |
6d7d7433 HY |
272 | This option will cause struct boot_params to be exported via debugfs. |
273 | ||
0c42f392 | 274 | config CPA_DEBUG |
971a52d6 | 275 | bool "CPA self-test code" |
f316fe68 | 276 | depends on DEBUG_KERNEL |
8f9ca475 | 277 | ---help--- |
971a52d6 | 278 | Do change_page_attr() self-tests every 30 seconds. |
0c42f392 | 279 | |
60a3cdd0 IM |
280 | config OPTIMIZE_INLINING |
281 | bool "Allow gcc to uninline functions marked 'inline'" | |
8f9ca475 | 282 | ---help--- |
60a3cdd0 IM |
283 | This option determines if the kernel forces gcc to inline the functions |
284 | developers have marked 'inline'. Doing so takes away freedom from gcc to | |
285 | do what it thinks is best, which is desirable for the gcc 3.x series of | |
286 | compilers. The gcc 4.x series have a rewritten inlining algorithm and | |
63fb7085 SW |
287 | enabling this option will generate a smaller kernel there. Hopefully |
288 | this algorithm is so good that allowing gcc 4.x and above to make the | |
289 | decision will become the default in the future. Until then this option | |
290 | is there to test gcc for this. | |
c9af1e33 | 291 | |
3f9b5cc0 IM |
292 | If unsure, say N. |
293 | ||
99e8b9ca DZ |
294 | config DEBUG_NMI_SELFTEST |
295 | bool "NMI Selftest" | |
4f941c57 | 296 | depends on DEBUG_KERNEL && X86_LOCAL_APIC |
99e8b9ca DZ |
297 | ---help--- |
298 | Enabling this option turns on a quick NMI selftest to verify | |
299 | that the NMI behaves correctly. | |
300 | ||
301 | This might help diagnose strange hangs that rely on NMI to | |
302 | function properly. | |
303 | ||
304 | If unsure, say N. | |
305 | ||
5700f743 BP |
306 | config X86_DEBUG_STATIC_CPU_HAS |
307 | bool "Debug alternatives" | |
308 | depends on DEBUG_KERNEL | |
309 | ---help--- | |
310 | This option causes additional code to be generated which | |
311 | fails if static_cpu_has() is used before alternatives have | |
312 | run. | |
313 | ||
314 | If unsure, say N. | |
315 | ||
c9af1e33 | 316 | endmenu |