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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 | ||
6bcb13b3 BC |
8 | config X86_VERBOSE_BOOTUP |
9 | bool "Enable verbose x86 bootup info messages" | |
10 | default y | |
8f9ca475 | 11 | ---help--- |
6bcb13b3 BC |
12 | Enables the informational output from the decompression stage |
13 | (e.g. bzImage) of the boot. If you disable this you will still | |
14 | see errors. Disable this if you want silent bootup. | |
15 | ||
1da177e4 | 16 | config EARLY_PRINTK |
6a108a14 | 17 | bool "Early printk" if EXPERT |
1da177e4 | 18 | default y |
8f9ca475 | 19 | ---help--- |
1da177e4 LT |
20 | Write kernel log output directly into the VGA buffer or to a serial |
21 | port. | |
22 | ||
23 | This is useful for kernel debugging when your machine crashes very | |
24 | early before the console code is initialized. For normal operation | |
25 | it is not recommended because it looks ugly and doesn't cooperate | |
26 | with klogd/syslogd or the X server. You should normally N here, | |
27 | unless you want to debug such a crash. | |
28 | ||
5c05917e YL |
29 | config EARLY_PRINTK_DBGP |
30 | bool "Early printk via EHCI debug port" | |
9749986a | 31 | depends on EARLY_PRINTK && PCI |
8f9ca475 | 32 | ---help--- |
5c05917e YL |
33 | Write kernel log output directly into the EHCI debug port. |
34 | ||
35 | This is useful for kernel debugging when your machine crashes very | |
36 | early before the console code is initialized. For normal operation | |
37 | it is not recommended because it looks ugly and doesn't cooperate | |
38 | with klogd/syslogd or the X server. You should normally N here, | |
39 | unless you want to debug such a crash. You need usb debug device. | |
40 | ||
72548e83 MF |
41 | config EARLY_PRINTK_EFI |
42 | bool "Early printk via the EFI framebuffer" | |
43 | depends on EFI && EARLY_PRINTK | |
44 | select FONT_SUPPORT | |
45 | ---help--- | |
46 | Write kernel log output directly into the EFI framebuffer. | |
47 | ||
48 | This is useful for kernel debugging when your machine crashes very | |
49 | early before the console code is initialized. | |
50 | ||
e1a58320 SS |
51 | config X86_PTDUMP_CORE |
52 | def_bool n | |
53 | ||
926e5392 | 54 | config X86_PTDUMP |
8609d1b5 | 55 | tristate "Export kernel pagetable layout to userspace via debugfs" |
fe770bf0 | 56 | depends on DEBUG_KERNEL |
926e5392 | 57 | select DEBUG_FS |
e1a58320 | 58 | select X86_PTDUMP_CORE |
8f9ca475 | 59 | ---help--- |
926e5392 AV |
60 | Say Y here if you want to show the kernel pagetable layout in a |
61 | debugfs file. This information is only useful for kernel developers | |
62 | who are working in architecture specific areas of the kernel. | |
63 | It is probably not a good idea to enable this feature in a production | |
64 | kernel. | |
65 | If in doubt, say "N" | |
66 | ||
11cc8512 BP |
67 | config EFI_PGT_DUMP |
68 | bool "Dump the EFI pagetable" | |
e1a58320 SS |
69 | depends on EFI |
70 | select X86_PTDUMP_CORE | |
11cc8512 BP |
71 | ---help--- |
72 | Enable this if you want to dump the EFI page table before | |
73 | enabling virtual mode. This can be used to debug miscellaneous | |
74 | issues with the mapping of the EFI runtime regions into that | |
75 | table. | |
76 | ||
e1a58320 SS |
77 | config DEBUG_WX |
78 | bool "Warn on W+X mappings at boot" | |
e1a58320 SS |
79 | select X86_PTDUMP_CORE |
80 | ---help--- | |
81 | Generate a warning if any W+X mappings are found at boot. | |
82 | ||
83 | This is useful for discovering cases where the kernel is leaving | |
84 | W+X mappings after applying NX, as such mappings are a security risk. | |
85 | ||
86 | Look for a message in dmesg output like this: | |
87 | ||
88 | x86/mm: Checked W+X mappings: passed, no W+X pages found. | |
89 | ||
90 | or like this, if the check failed: | |
91 | ||
92 | x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found. | |
93 | ||
94 | Note that even if the check fails, your kernel is possibly | |
95 | still fine, as W+X mappings are not a security hole in | |
96 | themselves, what they do is that they make the exploitation | |
97 | of other unfixed kernel bugs easier. | |
98 | ||
99 | There is no runtime or memory usage effect of this option | |
100 | once the kernel has booted up - it's a one time check. | |
101 | ||
102 | If in doubt, say "Y". | |
103 | ||
102e41fd AK |
104 | config DOUBLEFAULT |
105 | default y | |
6a108a14 | 106 | bool "Enable doublefault exception handler" if EXPERT |
8f9ca475 | 107 | ---help--- |
d013a27c RD |
108 | This option allows trapping of rare doublefault exceptions that |
109 | would otherwise cause a system to silently reboot. Disabling this | |
110 | option saves about 4k and might cause you much additional grey | |
111 | hair. | |
112 | ||
3df3212f AS |
113 | config DEBUG_TLBFLUSH |
114 | bool "Set upper limit of TLB entries to flush one-by-one" | |
cd69aa6b | 115 | depends on DEBUG_KERNEL |
3df3212f AS |
116 | ---help--- |
117 | ||
118 | X86-only for now. | |
119 | ||
120 | This option allows the user to tune the amount of TLB entries the | |
121 | kernel flushes one-by-one instead of doing a full TLB flush. In | |
122 | certain situations, the former is cheaper. This is controlled by the | |
123 | tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it | |
124 | to -1, the code flushes the whole TLB unconditionally. Otherwise, | |
125 | for positive values of it, the kernel will use single TLB entry | |
126 | invalidating instructions according to the following formula: | |
127 | ||
128 | flush_entries <= active_tlb_entries / 2^tlb_flushall_shift | |
129 | ||
130 | If in doubt, say "N". | |
131 | ||
d013a27c RD |
132 | config IOMMU_DEBUG |
133 | bool "Enable IOMMU debugging" | |
966396d3 | 134 | depends on GART_IOMMU && DEBUG_KERNEL |
d013a27c | 135 | depends on X86_64 |
8f9ca475 | 136 | ---help--- |
d013a27c RD |
137 | Force the IOMMU to on even when you have less than 4GB of |
138 | memory and add debugging code. On overflow always panic. And | |
139 | allow to enable IOMMU leak tracing. Can be disabled at boot | |
140 | time with iommu=noforce. This will also enable scatter gather | |
141 | list merging. Currently not recommended for production | |
142 | code. When you use it make sure you have a big enough | |
143 | IOMMU/AGP aperture. Most of the options enabled by this can | |
144 | be set more finegrained using the iommu= command line | |
395cf969 | 145 | options. See Documentation/x86/x86_64/boot-options.txt for more |
d013a27c RD |
146 | details. |
147 | ||
2be69c79 JR |
148 | config IOMMU_STRESS |
149 | bool "Enable IOMMU stress-test mode" | |
150 | ---help--- | |
151 | This option disables various optimizations in IOMMU related | |
152 | code to do real stress testing of the IOMMU code. This option | |
153 | will cause a performance drop and should only be enabled for | |
154 | testing. | |
155 | ||
d013a27c RD |
156 | config IOMMU_LEAK |
157 | bool "IOMMU leak tracing" | |
19c1a6f5 | 158 | depends on IOMMU_DEBUG && DMA_API_DEBUG |
8f9ca475 | 159 | ---help--- |
d013a27c RD |
160 | Add a simple leak tracer to the IOMMU code. This is useful when you |
161 | are debugging a buggy device driver that leaks IOMMU mappings. | |
162 | ||
6bc5c366 PP |
163 | config HAVE_MMIOTRACE_SUPPORT |
164 | def_bool y | |
8b7d89d0 | 165 | |
ca0e9bad | 166 | config X86_DECODER_SELFTEST |
cbe5c34c OH |
167 | bool "x86 instruction decoder selftest" |
168 | depends on DEBUG_KERNEL && KPROBES | |
f8f20234 | 169 | depends on !COMPILE_TEST |
ca0e9bad MH |
170 | ---help--- |
171 | Perform x86 instruction decoder selftests at build time. | |
172 | This option is useful for checking the sanity of x86 instruction | |
173 | decoder code. | |
174 | If unsure, say "N". | |
175 | ||
6e7c4025 IM |
176 | # |
177 | # IO delay types: | |
178 | # | |
179 | ||
180 | config IO_DELAY_TYPE_0X80 | |
181 | int | |
182 | default "0" | |
183 | ||
184 | config IO_DELAY_TYPE_0XED | |
185 | int | |
186 | default "1" | |
187 | ||
188 | config IO_DELAY_TYPE_UDELAY | |
189 | int | |
190 | default "2" | |
191 | ||
192 | config IO_DELAY_TYPE_NONE | |
193 | int | |
194 | default "3" | |
195 | ||
196 | choice | |
197 | prompt "IO delay type" | |
fd59e9e9 | 198 | default IO_DELAY_0X80 |
6e7c4025 IM |
199 | |
200 | config IO_DELAY_0X80 | |
201 | bool "port 0x80 based port-IO delay [recommended]" | |
8f9ca475 | 202 | ---help--- |
6e7c4025 IM |
203 | This is the traditional Linux IO delay used for in/out_p. |
204 | It is the most tested hence safest selection here. | |
205 | ||
206 | config IO_DELAY_0XED | |
207 | bool "port 0xed based port-IO delay" | |
8f9ca475 | 208 | ---help--- |
6e7c4025 IM |
209 | Use port 0xed as the IO delay. This frees up port 0x80 which is |
210 | often used as a hardware-debug port. | |
211 | ||
212 | config IO_DELAY_UDELAY | |
213 | bool "udelay based port-IO delay" | |
8f9ca475 | 214 | ---help--- |
6e7c4025 IM |
215 | Use udelay(2) as the IO delay method. This provides the delay |
216 | while not having any side-effect on the IO port space. | |
217 | ||
218 | config IO_DELAY_NONE | |
219 | bool "no port-IO delay" | |
8f9ca475 | 220 | ---help--- |
6e7c4025 IM |
221 | No port-IO delay. Will break on old boxes that require port-IO |
222 | delay for certain operations. Should work on most new machines. | |
223 | ||
224 | endchoice | |
225 | ||
226 | if IO_DELAY_0X80 | |
227 | config DEFAULT_IO_DELAY_TYPE | |
228 | int | |
229 | default IO_DELAY_TYPE_0X80 | |
230 | endif | |
231 | ||
232 | if IO_DELAY_0XED | |
233 | config DEFAULT_IO_DELAY_TYPE | |
234 | int | |
235 | default IO_DELAY_TYPE_0XED | |
236 | endif | |
237 | ||
238 | if IO_DELAY_UDELAY | |
239 | config DEFAULT_IO_DELAY_TYPE | |
240 | int | |
241 | default IO_DELAY_TYPE_UDELAY | |
242 | endif | |
243 | ||
244 | if IO_DELAY_NONE | |
245 | config DEFAULT_IO_DELAY_TYPE | |
246 | int | |
247 | default IO_DELAY_TYPE_NONE | |
248 | endif | |
b02aae9c | 249 | |
6d7d7433 HY |
250 | config DEBUG_BOOT_PARAMS |
251 | bool "Debug boot parameters" | |
252 | depends on DEBUG_KERNEL | |
253 | depends on DEBUG_FS | |
8f9ca475 | 254 | ---help--- |
6d7d7433 HY |
255 | This option will cause struct boot_params to be exported via debugfs. |
256 | ||
0c42f392 | 257 | config CPA_DEBUG |
971a52d6 | 258 | bool "CPA self-test code" |
f316fe68 | 259 | depends on DEBUG_KERNEL |
8f9ca475 | 260 | ---help--- |
971a52d6 | 261 | Do change_page_attr() self-tests every 30 seconds. |
0c42f392 | 262 | |
60a3cdd0 IM |
263 | config OPTIMIZE_INLINING |
264 | bool "Allow gcc to uninline functions marked 'inline'" | |
8f9ca475 | 265 | ---help--- |
60a3cdd0 IM |
266 | This option determines if the kernel forces gcc to inline the functions |
267 | developers have marked 'inline'. Doing so takes away freedom from gcc to | |
268 | do what it thinks is best, which is desirable for the gcc 3.x series of | |
269 | compilers. The gcc 4.x series have a rewritten inlining algorithm and | |
63fb7085 SW |
270 | enabling this option will generate a smaller kernel there. Hopefully |
271 | this algorithm is so good that allowing gcc 4.x and above to make the | |
272 | decision will become the default in the future. Until then this option | |
273 | is there to test gcc for this. | |
c9af1e33 | 274 | |
3f9b5cc0 IM |
275 | If unsure, say N. |
276 | ||
a97439aa AL |
277 | config DEBUG_ENTRY |
278 | bool "Debug low-level entry code" | |
279 | depends on DEBUG_KERNEL | |
280 | ---help--- | |
281 | This option enables sanity checks in x86's low-level entry code. | |
282 | Some of these sanity checks may slow down kernel entries and | |
283 | exits or otherwise impact performance. | |
284 | ||
285 | This is currently used to help test NMI code. | |
286 | ||
287 | If unsure, say N. | |
288 | ||
99e8b9ca DZ |
289 | config DEBUG_NMI_SELFTEST |
290 | bool "NMI Selftest" | |
4f941c57 | 291 | depends on DEBUG_KERNEL && X86_LOCAL_APIC |
99e8b9ca DZ |
292 | ---help--- |
293 | Enabling this option turns on a quick NMI selftest to verify | |
294 | that the NMI behaves correctly. | |
295 | ||
296 | This might help diagnose strange hangs that rely on NMI to | |
297 | function properly. | |
298 | ||
299 | If unsure, say N. | |
300 | ||
28a375df BD |
301 | config DEBUG_IMR_SELFTEST |
302 | bool "Isolated Memory Region self test" | |
303 | default n | |
304 | depends on INTEL_IMR | |
305 | ---help--- | |
306 | This option enables automated sanity testing of the IMR code. | |
307 | Some simple tests are run to verify IMR bounds checking, alignment | |
308 | and overlapping. This option is really only useful if you are | |
309 | debugging an IMR memory map or are modifying the IMR code and want to | |
310 | test your changes. | |
311 | ||
312 | If unsure say N here. | |
313 | ||
e97131a8 IM |
314 | config X86_DEBUG_FPU |
315 | bool "Debug the x86 FPU code" | |
316 | depends on DEBUG_KERNEL | |
317 | default y | |
318 | ---help--- | |
319 | If this option is enabled then there will be extra sanity | |
320 | checks and (boot time) debug printouts added to the kernel. | |
321 | This debugging adds some small amount of runtime overhead | |
322 | to the kernel. | |
323 | ||
324 | If unsure, say N. | |
325 | ||
956079e0 SP |
326 | config PUNIT_ATOM_DEBUG |
327 | tristate "ATOM Punit debug driver" | |
328 | select DEBUG_FS | |
329 | select IOSF_MBI | |
330 | ---help--- | |
331 | This is a debug driver, which gets the power states | |
332 | of all Punit North Complex devices. The power states of | |
333 | each device is exposed as part of the debugfs interface. | |
334 | The current power state can be read from | |
335 | /sys/kernel/debug/punit_atom/dev_power_state | |
336 | ||
c9af1e33 | 337 | endmenu |