1menu "Kernel hacking" 2 3config TRACE_IRQFLAGS_SUPPORT 4 def_bool y 5 6source "lib/Kconfig.debug" 7 8config X86_VERBOSE_BOOTUP 9 bool "Enable verbose x86 bootup info messages" 10 default y 11 ---help--- 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 16config EARLY_PRINTK 17 bool "Early printk" if EXPERT 18 default y 19 ---help--- 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 29config EARLY_PRINTK_DBGP 30 bool "Early printk via EHCI debug port" 31 depends on EARLY_PRINTK && PCI 32 ---help--- 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 41config 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 51config X86_PTDUMP_CORE 52 def_bool n 53 54config X86_PTDUMP 55 tristate "Export kernel pagetable layout to userspace via debugfs" 56 depends on DEBUG_KERNEL 57 select DEBUG_FS 58 select X86_PTDUMP_CORE 59 ---help--- 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 67config EFI_PGT_DUMP 68 bool "Dump the EFI pagetable" 69 depends on EFI 70 select X86_PTDUMP_CORE 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 77config DEBUG_RODATA_TEST 78 bool "Testcase for the marking rodata read-only" 79 default y 80 ---help--- 81 This option enables a testcase for the setting rodata read-only 82 as well as for the change_page_attr() infrastructure. 83 If in doubt, say "N" 84 85config DEBUG_WX 86 bool "Warn on W+X mappings at boot" 87 select X86_PTDUMP_CORE 88 ---help--- 89 Generate a warning if any W+X mappings are found at boot. 90 91 This is useful for discovering cases where the kernel is leaving 92 W+X mappings after applying NX, as such mappings are a security risk. 93 94 Look for a message in dmesg output like this: 95 96 x86/mm: Checked W+X mappings: passed, no W+X pages found. 97 98 or like this, if the check failed: 99 100 x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found. 101 102 Note that even if the check fails, your kernel is possibly 103 still fine, as W+X mappings are not a security hole in 104 themselves, what they do is that they make the exploitation 105 of other unfixed kernel bugs easier. 106 107 There is no runtime or memory usage effect of this option 108 once the kernel has booted up - it's a one time check. 109 110 If in doubt, say "Y". 111 112config DEBUG_SET_MODULE_RONX 113 bool "Set loadable kernel module data as NX and text as RO" 114 depends on MODULES 115 ---help--- 116 This option helps catch unintended modifications to loadable 117 kernel module's text and read-only data. It also prevents execution 118 of module data. Such protection may interfere with run-time code 119 patching and dynamic kernel tracing - and they might also protect 120 against certain classes of kernel exploits. 121 If in doubt, say "N". 122 123config DEBUG_NX_TEST 124 tristate "Testcase for the NX non-executable stack feature" 125 depends on DEBUG_KERNEL && m 126 ---help--- 127 This option enables a testcase for the CPU NX capability 128 and the software setup of this feature. 129 If in doubt, say "N" 130 131config DOUBLEFAULT 132 default y 133 bool "Enable doublefault exception handler" if EXPERT 134 ---help--- 135 This option allows trapping of rare doublefault exceptions that 136 would otherwise cause a system to silently reboot. Disabling this 137 option saves about 4k and might cause you much additional grey 138 hair. 139 140config DEBUG_TLBFLUSH 141 bool "Set upper limit of TLB entries to flush one-by-one" 142 depends on DEBUG_KERNEL 143 ---help--- 144 145 X86-only for now. 146 147 This option allows the user to tune the amount of TLB entries the 148 kernel flushes one-by-one instead of doing a full TLB flush. In 149 certain situations, the former is cheaper. This is controlled by the 150 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it 151 to -1, the code flushes the whole TLB unconditionally. Otherwise, 152 for positive values of it, the kernel will use single TLB entry 153 invalidating instructions according to the following formula: 154 155 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift 156 157 If in doubt, say "N". 158 159config IOMMU_DEBUG 160 bool "Enable IOMMU debugging" 161 depends on GART_IOMMU && DEBUG_KERNEL 162 depends on X86_64 163 ---help--- 164 Force the IOMMU to on even when you have less than 4GB of 165 memory and add debugging code. On overflow always panic. And 166 allow to enable IOMMU leak tracing. Can be disabled at boot 167 time with iommu=noforce. This will also enable scatter gather 168 list merging. Currently not recommended for production 169 code. When you use it make sure you have a big enough 170 IOMMU/AGP aperture. Most of the options enabled by this can 171 be set more finegrained using the iommu= command line 172 options. See Documentation/x86/x86_64/boot-options.txt for more 173 details. 174 175config IOMMU_STRESS 176 bool "Enable IOMMU stress-test mode" 177 ---help--- 178 This option disables various optimizations in IOMMU related 179 code to do real stress testing of the IOMMU code. This option 180 will cause a performance drop and should only be enabled for 181 testing. 182 183config IOMMU_LEAK 184 bool "IOMMU leak tracing" 185 depends on IOMMU_DEBUG && DMA_API_DEBUG 186 ---help--- 187 Add a simple leak tracer to the IOMMU code. This is useful when you 188 are debugging a buggy device driver that leaks IOMMU mappings. 189 190config HAVE_MMIOTRACE_SUPPORT 191 def_bool y 192 193config X86_DECODER_SELFTEST 194 bool "x86 instruction decoder selftest" 195 depends on DEBUG_KERNEL && KPROBES 196 depends on !COMPILE_TEST 197 ---help--- 198 Perform x86 instruction decoder selftests at build time. 199 This option is useful for checking the sanity of x86 instruction 200 decoder code. 201 If unsure, say "N". 202 203# 204# IO delay types: 205# 206 207config IO_DELAY_TYPE_0X80 208 int 209 default "0" 210 211config IO_DELAY_TYPE_0XED 212 int 213 default "1" 214 215config IO_DELAY_TYPE_UDELAY 216 int 217 default "2" 218 219config IO_DELAY_TYPE_NONE 220 int 221 default "3" 222 223choice 224 prompt "IO delay type" 225 default IO_DELAY_0X80 226 227config IO_DELAY_0X80 228 bool "port 0x80 based port-IO delay [recommended]" 229 ---help--- 230 This is the traditional Linux IO delay used for in/out_p. 231 It is the most tested hence safest selection here. 232 233config IO_DELAY_0XED 234 bool "port 0xed based port-IO delay" 235 ---help--- 236 Use port 0xed as the IO delay. This frees up port 0x80 which is 237 often used as a hardware-debug port. 238 239config IO_DELAY_UDELAY 240 bool "udelay based port-IO delay" 241 ---help--- 242 Use udelay(2) as the IO delay method. This provides the delay 243 while not having any side-effect on the IO port space. 244 245config IO_DELAY_NONE 246 bool "no port-IO delay" 247 ---help--- 248 No port-IO delay. Will break on old boxes that require port-IO 249 delay for certain operations. Should work on most new machines. 250 251endchoice 252 253if IO_DELAY_0X80 254config DEFAULT_IO_DELAY_TYPE 255 int 256 default IO_DELAY_TYPE_0X80 257endif 258 259if IO_DELAY_0XED 260config DEFAULT_IO_DELAY_TYPE 261 int 262 default IO_DELAY_TYPE_0XED 263endif 264 265if IO_DELAY_UDELAY 266config DEFAULT_IO_DELAY_TYPE 267 int 268 default IO_DELAY_TYPE_UDELAY 269endif 270 271if IO_DELAY_NONE 272config DEFAULT_IO_DELAY_TYPE 273 int 274 default IO_DELAY_TYPE_NONE 275endif 276 277config DEBUG_BOOT_PARAMS 278 bool "Debug boot parameters" 279 depends on DEBUG_KERNEL 280 depends on DEBUG_FS 281 ---help--- 282 This option will cause struct boot_params to be exported via debugfs. 283 284config CPA_DEBUG 285 bool "CPA self-test code" 286 depends on DEBUG_KERNEL 287 ---help--- 288 Do change_page_attr() self-tests every 30 seconds. 289 290config OPTIMIZE_INLINING 291 bool "Allow gcc to uninline functions marked 'inline'" 292 ---help--- 293 This option determines if the kernel forces gcc to inline the functions 294 developers have marked 'inline'. Doing so takes away freedom from gcc to 295 do what it thinks is best, which is desirable for the gcc 3.x series of 296 compilers. The gcc 4.x series have a rewritten inlining algorithm and 297 enabling this option will generate a smaller kernel there. Hopefully 298 this algorithm is so good that allowing gcc 4.x and above to make the 299 decision will become the default in the future. Until then this option 300 is there to test gcc for this. 301 302 If unsure, say N. 303 304config DEBUG_ENTRY 305 bool "Debug low-level entry code" 306 depends on DEBUG_KERNEL 307 ---help--- 308 This option enables sanity checks in x86's low-level entry code. 309 Some of these sanity checks may slow down kernel entries and 310 exits or otherwise impact performance. 311 312 This is currently used to help test NMI code. 313 314 If unsure, say N. 315 316config DEBUG_NMI_SELFTEST 317 bool "NMI Selftest" 318 depends on DEBUG_KERNEL && X86_LOCAL_APIC 319 ---help--- 320 Enabling this option turns on a quick NMI selftest to verify 321 that the NMI behaves correctly. 322 323 This might help diagnose strange hangs that rely on NMI to 324 function properly. 325 326 If unsure, say N. 327 328config DEBUG_IMR_SELFTEST 329 bool "Isolated Memory Region self test" 330 default n 331 depends on INTEL_IMR 332 ---help--- 333 This option enables automated sanity testing of the IMR code. 334 Some simple tests are run to verify IMR bounds checking, alignment 335 and overlapping. This option is really only useful if you are 336 debugging an IMR memory map or are modifying the IMR code and want to 337 test your changes. 338 339 If unsure say N here. 340 341config X86_DEBUG_FPU 342 bool "Debug the x86 FPU code" 343 depends on DEBUG_KERNEL 344 default y 345 ---help--- 346 If this option is enabled then there will be extra sanity 347 checks and (boot time) debug printouts added to the kernel. 348 This debugging adds some small amount of runtime overhead 349 to the kernel. 350 351 If unsure, say N. 352 353config PUNIT_ATOM_DEBUG 354 tristate "ATOM Punit debug driver" 355 select DEBUG_FS 356 select IOSF_MBI 357 ---help--- 358 This is a debug driver, which gets the power states 359 of all Punit North Complex devices. The power states of 360 each device is exposed as part of the debugfs interface. 361 The current power state can be read from 362 /sys/kernel/debug/punit_atom/dev_power_state 363 364endmenu 365