1menu "Kernel hacking" 2 3config TRACE_IRQFLAGS_SUPPORT 4 def_bool y 5 6source "lib/Kconfig.debug" 7 8config STRICT_DEVMEM 9 bool "Filter access to /dev/mem" 10 ---help--- 11 If this option is disabled, you allow userspace (root) access to all 12 of memory, including kernel and userspace memory. Accidental 13 access to this is obviously disastrous, but specific access can 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. 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. 24 25config X86_VERBOSE_BOOTUP 26 bool "Enable verbose x86 bootup info messages" 27 default y 28 ---help--- 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 33config EARLY_PRINTK 34 bool "Early printk" if EXPERT 35 default y 36 ---help--- 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 46config EARLY_PRINTK_DBGP 47 bool "Early printk via EHCI debug port" 48 depends on EARLY_PRINTK && PCI 49 ---help--- 50 Write kernel log output directly into the EHCI debug port. 51 52 This is useful for kernel debugging when your machine crashes very 53 early before the console code is initialized. For normal operation 54 it is not recommended because it looks ugly and doesn't cooperate 55 with klogd/syslogd or the X server. You should normally N here, 56 unless you want to debug such a crash. You need usb debug device. 57 58config EARLY_PRINTK_EFI 59 bool "Early printk via the EFI framebuffer" 60 depends on EFI && EARLY_PRINTK 61 select FONT_SUPPORT 62 ---help--- 63 Write kernel log output directly into the EFI framebuffer. 64 65 This is useful for kernel debugging when your machine crashes very 66 early before the console code is initialized. 67 68config X86_PTDUMP 69 bool "Export kernel pagetable layout to userspace via debugfs" 70 depends on DEBUG_KERNEL 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 80config EFI_PGT_DUMP 81 bool "Dump the EFI pagetable" 82 depends on EFI && X86_PTDUMP 83 ---help--- 84 Enable this if you want to dump the EFI page table before 85 enabling virtual mode. This can be used to debug miscellaneous 86 issues with the mapping of the EFI runtime regions into that 87 table. 88 89config DEBUG_RODATA 90 bool "Write protect kernel read-only data structures" 91 default y 92 depends on DEBUG_KERNEL 93 ---help--- 94 Mark the kernel read-only data as write-protected in the pagetables, 95 in order to catch accidental (and incorrect) writes to such const 96 data. This is recommended so that we can catch kernel bugs sooner. 97 If in doubt, say "Y". 98 99config DEBUG_RODATA_TEST 100 bool "Testcase for the DEBUG_RODATA feature" 101 depends on DEBUG_RODATA 102 default y 103 ---help--- 104 This option enables a testcase for the DEBUG_RODATA 105 feature as well as for the change_page_attr() infrastructure. 106 If in doubt, say "N" 107 108config DEBUG_SET_MODULE_RONX 109 bool "Set loadable kernel module data as NX and text as RO" 110 depends on MODULES 111 ---help--- 112 This option helps catch unintended modifications to loadable 113 kernel module's text and read-only data. It also prevents execution 114 of module data. Such protection may interfere with run-time code 115 patching and dynamic kernel tracing - and they might also protect 116 against certain classes of kernel exploits. 117 If in doubt, say "N". 118 119config DEBUG_NX_TEST 120 tristate "Testcase for the NX non-executable stack feature" 121 depends on DEBUG_KERNEL && m 122 ---help--- 123 This option enables a testcase for the CPU NX capability 124 and the software setup of this feature. 125 If in doubt, say "N" 126 127config DOUBLEFAULT 128 default y 129 bool "Enable doublefault exception handler" if EXPERT 130 ---help--- 131 This option allows trapping of rare doublefault exceptions that 132 would otherwise cause a system to silently reboot. Disabling this 133 option saves about 4k and might cause you much additional grey 134 hair. 135 136config DEBUG_TLBFLUSH 137 bool "Set upper limit of TLB entries to flush one-by-one" 138 depends on DEBUG_KERNEL 139 ---help--- 140 141 X86-only for now. 142 143 This option allows the user to tune the amount of TLB entries the 144 kernel flushes one-by-one instead of doing a full TLB flush. In 145 certain situations, the former is cheaper. This is controlled by the 146 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it 147 to -1, the code flushes the whole TLB unconditionally. Otherwise, 148 for positive values of it, the kernel will use single TLB entry 149 invalidating instructions according to the following formula: 150 151 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift 152 153 If in doubt, say "N". 154 155config IOMMU_DEBUG 156 bool "Enable IOMMU debugging" 157 depends on GART_IOMMU && DEBUG_KERNEL 158 depends on X86_64 159 ---help--- 160 Force the IOMMU to on even when you have less than 4GB of 161 memory and add debugging code. On overflow always panic. And 162 allow to enable IOMMU leak tracing. Can be disabled at boot 163 time with iommu=noforce. This will also enable scatter gather 164 list merging. Currently not recommended for production 165 code. When you use it make sure you have a big enough 166 IOMMU/AGP aperture. Most of the options enabled by this can 167 be set more finegrained using the iommu= command line 168 options. See Documentation/x86/x86_64/boot-options.txt for more 169 details. 170 171config IOMMU_STRESS 172 bool "Enable IOMMU stress-test mode" 173 ---help--- 174 This option disables various optimizations in IOMMU related 175 code to do real stress testing of the IOMMU code. This option 176 will cause a performance drop and should only be enabled for 177 testing. 178 179config IOMMU_LEAK 180 bool "IOMMU leak tracing" 181 depends on IOMMU_DEBUG && DMA_API_DEBUG 182 ---help--- 183 Add a simple leak tracer to the IOMMU code. This is useful when you 184 are debugging a buggy device driver that leaks IOMMU mappings. 185 186config HAVE_MMIOTRACE_SUPPORT 187 def_bool y 188 189config X86_DECODER_SELFTEST 190 bool "x86 instruction decoder selftest" 191 depends on DEBUG_KERNEL && KPROBES 192 depends on !COMPILE_TEST 193 ---help--- 194 Perform x86 instruction decoder selftests at build time. 195 This option is useful for checking the sanity of x86 instruction 196 decoder code. 197 If unsure, say "N". 198 199# 200# IO delay types: 201# 202 203config IO_DELAY_TYPE_0X80 204 int 205 default "0" 206 207config IO_DELAY_TYPE_0XED 208 int 209 default "1" 210 211config IO_DELAY_TYPE_UDELAY 212 int 213 default "2" 214 215config IO_DELAY_TYPE_NONE 216 int 217 default "3" 218 219choice 220 prompt "IO delay type" 221 default IO_DELAY_0X80 222 223config IO_DELAY_0X80 224 bool "port 0x80 based port-IO delay [recommended]" 225 ---help--- 226 This is the traditional Linux IO delay used for in/out_p. 227 It is the most tested hence safest selection here. 228 229config IO_DELAY_0XED 230 bool "port 0xed based port-IO delay" 231 ---help--- 232 Use port 0xed as the IO delay. This frees up port 0x80 which is 233 often used as a hardware-debug port. 234 235config IO_DELAY_UDELAY 236 bool "udelay based port-IO delay" 237 ---help--- 238 Use udelay(2) as the IO delay method. This provides the delay 239 while not having any side-effect on the IO port space. 240 241config IO_DELAY_NONE 242 bool "no port-IO delay" 243 ---help--- 244 No port-IO delay. Will break on old boxes that require port-IO 245 delay for certain operations. Should work on most new machines. 246 247endchoice 248 249if IO_DELAY_0X80 250config DEFAULT_IO_DELAY_TYPE 251 int 252 default IO_DELAY_TYPE_0X80 253endif 254 255if IO_DELAY_0XED 256config DEFAULT_IO_DELAY_TYPE 257 int 258 default IO_DELAY_TYPE_0XED 259endif 260 261if IO_DELAY_UDELAY 262config DEFAULT_IO_DELAY_TYPE 263 int 264 default IO_DELAY_TYPE_UDELAY 265endif 266 267if IO_DELAY_NONE 268config DEFAULT_IO_DELAY_TYPE 269 int 270 default IO_DELAY_TYPE_NONE 271endif 272 273config DEBUG_BOOT_PARAMS 274 bool "Debug boot parameters" 275 depends on DEBUG_KERNEL 276 depends on DEBUG_FS 277 ---help--- 278 This option will cause struct boot_params to be exported via debugfs. 279 280config CPA_DEBUG 281 bool "CPA self-test code" 282 depends on DEBUG_KERNEL 283 ---help--- 284 Do change_page_attr() self-tests every 30 seconds. 285 286config OPTIMIZE_INLINING 287 bool "Allow gcc to uninline functions marked 'inline'" 288 ---help--- 289 This option determines if the kernel forces gcc to inline the functions 290 developers have marked 'inline'. Doing so takes away freedom from gcc to 291 do what it thinks is best, which is desirable for the gcc 3.x series of 292 compilers. The gcc 4.x series have a rewritten inlining algorithm and 293 enabling this option will generate a smaller kernel there. Hopefully 294 this algorithm is so good that allowing gcc 4.x and above to make the 295 decision will become the default in the future. Until then this option 296 is there to test gcc for this. 297 298 If unsure, say N. 299 300config DEBUG_NMI_SELFTEST 301 bool "NMI Selftest" 302 depends on DEBUG_KERNEL && X86_LOCAL_APIC 303 ---help--- 304 Enabling this option turns on a quick NMI selftest to verify 305 that the NMI behaves correctly. 306 307 This might help diagnose strange hangs that rely on NMI to 308 function properly. 309 310 If unsure, say N. 311 312config DEBUG_IMR_SELFTEST 313 bool "Isolated Memory Region self test" 314 default n 315 depends on INTEL_IMR 316 ---help--- 317 This option enables automated sanity testing of the IMR code. 318 Some simple tests are run to verify IMR bounds checking, alignment 319 and overlapping. This option is really only useful if you are 320 debugging an IMR memory map or are modifying the IMR code and want to 321 test your changes. 322 323 If unsure say N here. 324 325config X86_DEBUG_STATIC_CPU_HAS 326 bool "Debug alternatives" 327 depends on DEBUG_KERNEL 328 ---help--- 329 This option causes additional code to be generated which 330 fails if static_cpu_has() is used before alternatives have 331 run. 332 333 If unsure, say N. 334 335endmenu 336