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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" | |
48 | default n | |
9749986a | 49 | depends on EARLY_PRINTK && PCI |
8f9ca475 | 50 | ---help--- |
5c05917e YL |
51 | Write kernel log output directly into the EHCI debug port. |
52 | ||
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. | |
58 | ||
1da177e4 LT |
59 | config DEBUG_STACKOVERFLOW |
60 | bool "Check for stack overflows" | |
61 | depends on DEBUG_KERNEL | |
8f9ca475 | 62 | ---help--- |
dab175f3 AB |
63 | This option will cause messages to be printed if free stack space |
64 | drops below a certain limit. | |
1da177e4 | 65 | |
1da177e4 LT |
66 | config DEBUG_STACK_USAGE |
67 | bool "Stack utilization instrumentation" | |
68 | depends on DEBUG_KERNEL | |
8f9ca475 | 69 | ---help--- |
1da177e4 LT |
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. | |
72 | ||
73 | This option will slow down process creation somewhat. | |
74 | ||
c49a4955 | 75 | config DEBUG_PER_CPU_MAPS |
76 | bool "Debug access to per_cpu maps" | |
77 | depends on DEBUG_KERNEL | |
3e5095d1 | 78 | depends on SMP |
c49a4955 | 79 | default n |
8f9ca475 | 80 | ---help--- |
c49a4955 | 81 | Say Y to verify that the per_cpu map being accessed has |
82 | been setup. Adds a fair amount of code to kernel memory | |
83 | and decreases performance. | |
84 | ||
85 | Say N if unsure. | |
86 | ||
926e5392 AV |
87 | config X86_PTDUMP |
88 | bool "Export kernel pagetable layout to userspace via debugfs" | |
fe770bf0 | 89 | depends on DEBUG_KERNEL |
926e5392 | 90 | select DEBUG_FS |
8f9ca475 | 91 | ---help--- |
926e5392 AV |
92 | Say Y here if you want to show the kernel pagetable layout in a |
93 | debugfs file. This information is only useful for kernel developers | |
94 | who are working in architecture specific areas of the kernel. | |
95 | It is probably not a good idea to enable this feature in a production | |
96 | kernel. | |
97 | If in doubt, say "N" | |
98 | ||
63aaf308 AV |
99 | config DEBUG_RODATA |
100 | bool "Write protect kernel read-only data structures" | |
11201e60 | 101 | default y |
63aaf308 | 102 | depends on DEBUG_KERNEL |
8f9ca475 | 103 | ---help--- |
63aaf308 AV |
104 | Mark the kernel read-only data as write-protected in the pagetables, |
105 | in order to catch accidental (and incorrect) writes to such const | |
11201e60 IM |
106 | data. This is recommended so that we can catch kernel bugs sooner. |
107 | If in doubt, say "Y". | |
63aaf308 | 108 | |
aba8391f IM |
109 | config DEBUG_RODATA_TEST |
110 | bool "Testcase for the DEBUG_RODATA feature" | |
111 | depends on DEBUG_RODATA | |
72370f2a | 112 | default y |
8f9ca475 | 113 | ---help--- |
aba8391f IM |
114 | This option enables a testcase for the DEBUG_RODATA |
115 | feature as well as for the change_page_attr() infrastructure. | |
116 | If in doubt, say "N" | |
117 | ||
118 | config DEBUG_NX_TEST | |
119 | tristate "Testcase for the NX non-executable stack feature" | |
120 | depends on DEBUG_KERNEL && m | |
8f9ca475 | 121 | ---help--- |
aba8391f IM |
122 | This option enables a testcase for the CPU NX capability |
123 | and the software setup of this feature. | |
124 | If in doubt, say "N" | |
125 | ||
1da177e4 LT |
126 | config 4KSTACKS |
127 | bool "Use 4Kb for kernel stacks instead of 8Kb" | |
d013a27c | 128 | depends on X86_32 |
8f9ca475 | 129 | ---help--- |
1da177e4 LT |
130 | If you say Y here the kernel will use a 4Kb stacksize for the |
131 | kernel stack attached to each process/thread. This facilitates | |
132 | running more threads on a system and also reduces the pressure | |
133 | on the VM subsystem for higher order allocations. This option | |
134 | will also use IRQ stacks to compensate for the reduced stackspace. | |
135 | ||
102e41fd AK |
136 | config DOUBLEFAULT |
137 | default y | |
138 | bool "Enable doublefault exception handler" if EMBEDDED | |
d013a27c | 139 | depends on X86_32 |
8f9ca475 | 140 | ---help--- |
d013a27c RD |
141 | This option allows trapping of rare doublefault exceptions that |
142 | would otherwise cause a system to silently reboot. Disabling this | |
143 | option saves about 4k and might cause you much additional grey | |
144 | hair. | |
145 | ||
146 | config IOMMU_DEBUG | |
147 | bool "Enable IOMMU debugging" | |
966396d3 | 148 | depends on GART_IOMMU && DEBUG_KERNEL |
d013a27c | 149 | depends on X86_64 |
8f9ca475 | 150 | ---help--- |
d013a27c RD |
151 | Force the IOMMU to on even when you have less than 4GB of |
152 | memory and add debugging code. On overflow always panic. And | |
153 | allow to enable IOMMU leak tracing. Can be disabled at boot | |
154 | time with iommu=noforce. This will also enable scatter gather | |
155 | list merging. Currently not recommended for production | |
156 | code. When you use it make sure you have a big enough | |
157 | IOMMU/AGP aperture. Most of the options enabled by this can | |
158 | be set more finegrained using the iommu= command line | |
159 | options. See Documentation/x86_64/boot-options.txt for more | |
160 | details. | |
161 | ||
162 | config IOMMU_LEAK | |
163 | bool "IOMMU leak tracing" | |
19c1a6f5 | 164 | depends on IOMMU_DEBUG && DMA_API_DEBUG |
8f9ca475 | 165 | ---help--- |
d013a27c RD |
166 | Add a simple leak tracer to the IOMMU code. This is useful when you |
167 | are debugging a buggy device driver that leaks IOMMU mappings. | |
168 | ||
6bc5c366 PP |
169 | config HAVE_MMIOTRACE_SUPPORT |
170 | def_bool y | |
8b7d89d0 | 171 | |
6e7c4025 IM |
172 | # |
173 | # IO delay types: | |
174 | # | |
175 | ||
176 | config IO_DELAY_TYPE_0X80 | |
177 | int | |
178 | default "0" | |
179 | ||
180 | config IO_DELAY_TYPE_0XED | |
181 | int | |
182 | default "1" | |
183 | ||
184 | config IO_DELAY_TYPE_UDELAY | |
185 | int | |
186 | default "2" | |
187 | ||
188 | config IO_DELAY_TYPE_NONE | |
189 | int | |
190 | default "3" | |
191 | ||
192 | choice | |
193 | prompt "IO delay type" | |
fd59e9e9 | 194 | default IO_DELAY_0X80 |
6e7c4025 IM |
195 | |
196 | config IO_DELAY_0X80 | |
197 | bool "port 0x80 based port-IO delay [recommended]" | |
8f9ca475 | 198 | ---help--- |
6e7c4025 IM |
199 | This is the traditional Linux IO delay used for in/out_p. |
200 | It is the most tested hence safest selection here. | |
201 | ||
202 | config IO_DELAY_0XED | |
203 | bool "port 0xed based port-IO delay" | |
8f9ca475 | 204 | ---help--- |
6e7c4025 IM |
205 | Use port 0xed as the IO delay. This frees up port 0x80 which is |
206 | often used as a hardware-debug port. | |
207 | ||
208 | config IO_DELAY_UDELAY | |
209 | bool "udelay based port-IO delay" | |
8f9ca475 | 210 | ---help--- |
6e7c4025 IM |
211 | Use udelay(2) as the IO delay method. This provides the delay |
212 | while not having any side-effect on the IO port space. | |
213 | ||
214 | config IO_DELAY_NONE | |
215 | bool "no port-IO delay" | |
8f9ca475 | 216 | ---help--- |
6e7c4025 IM |
217 | No port-IO delay. Will break on old boxes that require port-IO |
218 | delay for certain operations. Should work on most new machines. | |
219 | ||
220 | endchoice | |
221 | ||
222 | if IO_DELAY_0X80 | |
223 | config DEFAULT_IO_DELAY_TYPE | |
224 | int | |
225 | default IO_DELAY_TYPE_0X80 | |
226 | endif | |
227 | ||
228 | if IO_DELAY_0XED | |
229 | config DEFAULT_IO_DELAY_TYPE | |
230 | int | |
231 | default IO_DELAY_TYPE_0XED | |
232 | endif | |
233 | ||
234 | if IO_DELAY_UDELAY | |
235 | config DEFAULT_IO_DELAY_TYPE | |
236 | int | |
237 | default IO_DELAY_TYPE_UDELAY | |
238 | endif | |
239 | ||
240 | if IO_DELAY_NONE | |
241 | config DEFAULT_IO_DELAY_TYPE | |
242 | int | |
243 | default IO_DELAY_TYPE_NONE | |
244 | endif | |
b02aae9c | 245 | |
6d7d7433 HY |
246 | config DEBUG_BOOT_PARAMS |
247 | bool "Debug boot parameters" | |
248 | depends on DEBUG_KERNEL | |
249 | depends on DEBUG_FS | |
8f9ca475 | 250 | ---help--- |
6d7d7433 HY |
251 | This option will cause struct boot_params to be exported via debugfs. |
252 | ||
0c42f392 | 253 | config CPA_DEBUG |
971a52d6 | 254 | bool "CPA self-test code" |
f316fe68 | 255 | depends on DEBUG_KERNEL |
8f9ca475 | 256 | ---help--- |
971a52d6 | 257 | Do change_page_attr() self-tests every 30 seconds. |
0c42f392 | 258 | |
60a3cdd0 IM |
259 | config OPTIMIZE_INLINING |
260 | bool "Allow gcc to uninline functions marked 'inline'" | |
8f9ca475 | 261 | ---help--- |
60a3cdd0 IM |
262 | This option determines if the kernel forces gcc to inline the functions |
263 | developers have marked 'inline'. Doing so takes away freedom from gcc to | |
264 | do what it thinks is best, which is desirable for the gcc 3.x series of | |
265 | compilers. The gcc 4.x series have a rewritten inlining algorithm and | |
63fb7085 SW |
266 | enabling this option will generate a smaller kernel there. Hopefully |
267 | this algorithm is so good that allowing gcc 4.x and above to make the | |
268 | decision will become the default in the future. Until then this option | |
269 | is there to test gcc for this. | |
c9af1e33 | 270 | |
3f9b5cc0 IM |
271 | If unsure, say N. |
272 | ||
c9af1e33 | 273 | endmenu |