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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 | ||
ae531c26 AV |
8 | config NONPROMISC_DEVMEM |
9 | bool "Disable promiscuous /dev/mem" | |
ae531c26 AV |
10 | help |
11 | The /dev/mem file by default only allows userspace access to PCI | |
12 | space and the BIOS code and data regions. This is sufficient for | |
13 | dosemu and X and all common users of /dev/mem. With this config | |
14 | option, you allow userspace access to all of memory, including | |
15 | kernel and userspace memory. Accidental access to this is | |
16 | obviously disasterous, but specific access can be used by people | |
17 | debugging the kernel. | |
18 | ||
1da177e4 | 19 | config EARLY_PRINTK |
076f9776 | 20 | bool "Early printk" if EMBEDDED |
1da177e4 LT |
21 | default y |
22 | help | |
23 | Write kernel log output directly into the VGA buffer or to a serial | |
24 | port. | |
25 | ||
26 | This is useful for kernel debugging when your machine crashes very | |
27 | early before the console code is initialized. For normal operation | |
28 | it is not recommended because it looks ugly and doesn't cooperate | |
29 | with klogd/syslogd or the X server. You should normally N here, | |
30 | unless you want to debug such a crash. | |
31 | ||
32 | config DEBUG_STACKOVERFLOW | |
33 | bool "Check for stack overflows" | |
34 | depends on DEBUG_KERNEL | |
dab175f3 AB |
35 | help |
36 | This option will cause messages to be printed if free stack space | |
37 | drops below a certain limit. | |
1da177e4 | 38 | |
1da177e4 LT |
39 | config DEBUG_STACK_USAGE |
40 | bool "Stack utilization instrumentation" | |
41 | depends on DEBUG_KERNEL | |
42 | help | |
43 | Enables the display of the minimum amount of free stack which each | |
44 | task has ever had available in the sysrq-T and sysrq-P debug output. | |
45 | ||
46 | This option will slow down process creation somewhat. | |
47 | ||
1da177e4 | 48 | config DEBUG_PAGEALLOC |
4a2f0acf | 49 | bool "Debug page memory allocations" |
b1d95f4e | 50 | depends on DEBUG_KERNEL |
1da177e4 LT |
51 | help |
52 | Unmap pages from the kernel linear mapping after free_pages(). | |
53 | This results in a large slowdown, but helps to find certain types | |
54 | of memory corruptions. | |
55 | ||
c49a4955 | 56 | config DEBUG_PER_CPU_MAPS |
57 | bool "Debug access to per_cpu maps" | |
58 | depends on DEBUG_KERNEL | |
59 | depends on X86_64_SMP | |
60 | default n | |
61 | help | |
62 | Say Y to verify that the per_cpu map being accessed has | |
63 | been setup. Adds a fair amount of code to kernel memory | |
64 | and decreases performance. | |
65 | ||
66 | Say N if unsure. | |
67 | ||
926e5392 AV |
68 | config X86_PTDUMP |
69 | bool "Export kernel pagetable layout to userspace via debugfs" | |
fe770bf0 | 70 | depends on DEBUG_KERNEL |
926e5392 AV |
71 | select DEBUG_FS |
72 | help | |
73 | Say Y here if you want to show the kernel pagetable layout in a | |
74 | debugfs file. This information is only useful for kernel developers | |
75 | who are working in architecture specific areas of the kernel. | |
76 | It is probably not a good idea to enable this feature in a production | |
77 | kernel. | |
78 | If in doubt, say "N" | |
79 | ||
63aaf308 AV |
80 | config DEBUG_RODATA |
81 | bool "Write protect kernel read-only data structures" | |
11201e60 | 82 | default y |
63aaf308 AV |
83 | depends on DEBUG_KERNEL |
84 | help | |
85 | Mark the kernel read-only data as write-protected in the pagetables, | |
86 | in order to catch accidental (and incorrect) writes to such const | |
11201e60 IM |
87 | data. This is recommended so that we can catch kernel bugs sooner. |
88 | If in doubt, say "Y". | |
63aaf308 | 89 | |
00d1c5e0 IM |
90 | config DIRECT_GBPAGES |
91 | bool "Enable gbpages-mapped kernel pagetables" | |
92 | depends on DEBUG_KERNEL && EXPERIMENTAL && X86_64 | |
93 | help | |
94 | Enable gigabyte pages support (if the CPU supports it). This can | |
95 | improve the kernel's performance a tiny bit by reducing TLB | |
96 | pressure. | |
97 | ||
98 | This is experimental code. | |
99 | ||
100 | If in doubt, say "N". | |
101 | ||
aba8391f IM |
102 | config DEBUG_RODATA_TEST |
103 | bool "Testcase for the DEBUG_RODATA feature" | |
104 | depends on DEBUG_RODATA | |
105 | help | |
106 | This option enables a testcase for the DEBUG_RODATA | |
107 | feature as well as for the change_page_attr() infrastructure. | |
108 | If in doubt, say "N" | |
109 | ||
110 | config DEBUG_NX_TEST | |
111 | tristate "Testcase for the NX non-executable stack feature" | |
112 | depends on DEBUG_KERNEL && m | |
113 | help | |
114 | This option enables a testcase for the CPU NX capability | |
115 | and the software setup of this feature. | |
116 | If in doubt, say "N" | |
117 | ||
1da177e4 LT |
118 | config 4KSTACKS |
119 | bool "Use 4Kb for kernel stacks instead of 8Kb" | |
d013a27c | 120 | depends on X86_32 |
1da177e4 LT |
121 | help |
122 | If you say Y here the kernel will use a 4Kb stacksize for the | |
123 | kernel stack attached to each process/thread. This facilitates | |
124 | running more threads on a system and also reduces the pressure | |
125 | on the VM subsystem for higher order allocations. This option | |
126 | will also use IRQ stacks to compensate for the reduced stackspace. | |
127 | ||
128 | config X86_FIND_SMP_CONFIG | |
d013a27c | 129 | def_bool y |
1da177e4 | 130 | depends on X86_LOCAL_APIC || X86_VOYAGER |
d013a27c | 131 | depends on X86_32 |
1da177e4 LT |
132 | |
133 | config X86_MPPARSE | |
d013a27c | 134 | def_bool y |
6b0c3d44 | 135 | depends on (X86_32 && (X86_LOCAL_APIC && !X86_VISWS)) || X86_64 |
1da177e4 | 136 | |
102e41fd AK |
137 | config DOUBLEFAULT |
138 | default y | |
139 | bool "Enable doublefault exception handler" if EMBEDDED | |
d013a27c RD |
140 | depends on X86_32 |
141 | help | |
142 | This option allows trapping of rare doublefault exceptions that | |
143 | would otherwise cause a system to silently reboot. Disabling this | |
144 | option saves about 4k and might cause you much additional grey | |
145 | hair. | |
146 | ||
147 | config IOMMU_DEBUG | |
148 | bool "Enable IOMMU debugging" | |
966396d3 | 149 | depends on GART_IOMMU && DEBUG_KERNEL |
d013a27c | 150 | depends on X86_64 |
102e41fd | 151 | help |
d013a27c RD |
152 | Force the IOMMU to on even when you have less than 4GB of |
153 | memory and add debugging code. On overflow always panic. And | |
154 | allow to enable IOMMU leak tracing. Can be disabled at boot | |
155 | time with iommu=noforce. This will also enable scatter gather | |
156 | list merging. Currently not recommended for production | |
157 | code. When you use it make sure you have a big enough | |
158 | IOMMU/AGP aperture. Most of the options enabled by this can | |
159 | be set more finegrained using the iommu= command line | |
160 | options. See Documentation/x86_64/boot-options.txt for more | |
161 | details. | |
162 | ||
163 | config IOMMU_LEAK | |
164 | bool "IOMMU leak tracing" | |
165 | depends on DEBUG_KERNEL | |
166 | depends on IOMMU_DEBUG | |
167 | help | |
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 | ||
6e7c4025 IM |
171 | # |
172 | # IO delay types: | |
173 | # | |
174 | ||
175 | config IO_DELAY_TYPE_0X80 | |
176 | int | |
177 | default "0" | |
178 | ||
179 | config IO_DELAY_TYPE_0XED | |
180 | int | |
181 | default "1" | |
182 | ||
183 | config IO_DELAY_TYPE_UDELAY | |
184 | int | |
185 | default "2" | |
186 | ||
187 | config IO_DELAY_TYPE_NONE | |
188 | int | |
189 | default "3" | |
190 | ||
191 | choice | |
192 | prompt "IO delay type" | |
fd59e9e9 | 193 | default IO_DELAY_0X80 |
6e7c4025 IM |
194 | |
195 | config IO_DELAY_0X80 | |
196 | bool "port 0x80 based port-IO delay [recommended]" | |
197 | help | |
198 | This is the traditional Linux IO delay used for in/out_p. | |
199 | It is the most tested hence safest selection here. | |
200 | ||
201 | config IO_DELAY_0XED | |
202 | bool "port 0xed based port-IO delay" | |
203 | help | |
204 | Use port 0xed as the IO delay. This frees up port 0x80 which is | |
205 | often used as a hardware-debug port. | |
206 | ||
207 | config IO_DELAY_UDELAY | |
208 | bool "udelay based port-IO delay" | |
209 | help | |
210 | Use udelay(2) as the IO delay method. This provides the delay | |
211 | while not having any side-effect on the IO port space. | |
212 | ||
213 | config IO_DELAY_NONE | |
214 | bool "no port-IO delay" | |
b02aae9c | 215 | help |
6e7c4025 IM |
216 | No port-IO delay. Will break on old boxes that require port-IO |
217 | delay for certain operations. Should work on most new machines. | |
218 | ||
219 | endchoice | |
220 | ||
221 | if IO_DELAY_0X80 | |
222 | config DEFAULT_IO_DELAY_TYPE | |
223 | int | |
224 | default IO_DELAY_TYPE_0X80 | |
225 | endif | |
226 | ||
227 | if IO_DELAY_0XED | |
228 | config DEFAULT_IO_DELAY_TYPE | |
229 | int | |
230 | default IO_DELAY_TYPE_0XED | |
231 | endif | |
232 | ||
233 | if IO_DELAY_UDELAY | |
234 | config DEFAULT_IO_DELAY_TYPE | |
235 | int | |
236 | default IO_DELAY_TYPE_UDELAY | |
237 | endif | |
238 | ||
239 | if IO_DELAY_NONE | |
240 | config DEFAULT_IO_DELAY_TYPE | |
241 | int | |
242 | default IO_DELAY_TYPE_NONE | |
243 | endif | |
b02aae9c | 244 | |
6d7d7433 HY |
245 | config DEBUG_BOOT_PARAMS |
246 | bool "Debug boot parameters" | |
247 | depends on DEBUG_KERNEL | |
248 | depends on DEBUG_FS | |
249 | help | |
250 | This option will cause struct boot_params to be exported via debugfs. | |
251 | ||
0c42f392 | 252 | config CPA_DEBUG |
971a52d6 | 253 | bool "CPA self-test code" |
f316fe68 | 254 | depends on DEBUG_KERNEL |
0c42f392 | 255 | help |
971a52d6 | 256 | Do change_page_attr() self-tests every 30 seconds. |
0c42f392 | 257 | |
60a3cdd0 IM |
258 | config OPTIMIZE_INLINING |
259 | bool "Allow gcc to uninline functions marked 'inline'" | |
6d98ca73 | 260 | depends on BROKEN |
60a3cdd0 IM |
261 | help |
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 | |
266 | disabling this option will generate a smaller kernel there. Hopefully | |
267 | this algorithm is so good that allowing gcc4 to make the decision can | |
268 | become the default in the future, until then this option is there to | |
269 | test gcc for this. | |
c9af1e33 IM |
270 | |
271 | endmenu | |
272 |