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 78 bool "Write protect kernel read-only data structures" 79 default y 80 depends on DEBUG_KERNEL 81 ---help--- 82 Mark the kernel read-only data as write-protected in the pagetables, 83 in order to catch accidental (and incorrect) writes to such const 84 data. This is recommended so that we can catch kernel bugs sooner. 85 If in doubt, say "Y". 86 87config DEBUG_RODATA_TEST 88 bool "Testcase for the DEBUG_RODATA feature" 89 depends on DEBUG_RODATA 90 default y 91 ---help--- 92 This option enables a testcase for the DEBUG_RODATA 93 feature as well as for the change_page_attr() infrastructure. 94 If in doubt, say "N" 95 96config DEBUG_WX 97 bool "Warn on W+X mappings at boot" 98 depends on DEBUG_RODATA 99 select X86_PTDUMP_CORE 100 ---help--- 101 Generate a warning if any W+X mappings are found at boot. 102 103 This is useful for discovering cases where the kernel is leaving 104 W+X mappings after applying NX, as such mappings are a security risk. 105 106 Look for a message in dmesg output like this: 107 108 x86/mm: Checked W+X mappings: passed, no W+X pages found. 109 110 or like this, if the check failed: 111 112 x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found. 113 114 Note that even if the check fails, your kernel is possibly 115 still fine, as W+X mappings are not a security hole in 116 themselves, what they do is that they make the exploitation 117 of other unfixed kernel bugs easier. 118 119 There is no runtime or memory usage effect of this option 120 once the kernel has booted up - it's a one time check. 121 122 If in doubt, say "Y". 123 124config DEBUG_SET_MODULE_RONX 125 bool "Set loadable kernel module data as NX and text as RO" 126 depends on MODULES 127 ---help--- 128 This option helps catch unintended modifications to loadable 129 kernel module's text and read-only data. It also prevents execution 130 of module data. Such protection may interfere with run-time code 131 patching and dynamic kernel tracing - and they might also protect 132 against certain classes of kernel exploits. 133 If in doubt, say "N". 134 135config DEBUG_NX_TEST 136 tristate "Testcase for the NX non-executable stack feature" 137 depends on DEBUG_KERNEL && m 138 ---help--- 139 This option enables a testcase for the CPU NX capability 140 and the software setup of this feature. 141 If in doubt, say "N" 142 143config DOUBLEFAULT 144 default y 145 bool "Enable doublefault exception handler" if EXPERT 146 ---help--- 147 This option allows trapping of rare doublefault exceptions that 148 would otherwise cause a system to silently reboot. Disabling this 149 option saves about 4k and might cause you much additional grey 150 hair. 151 152config DEBUG_TLBFLUSH 153 bool "Set upper limit of TLB entries to flush one-by-one" 154 depends on DEBUG_KERNEL 155 ---help--- 156 157 X86-only for now. 158 159 This option allows the user to tune the amount of TLB entries the 160 kernel flushes one-by-one instead of doing a full TLB flush. In 161 certain situations, the former is cheaper. This is controlled by the 162 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it 163 to -1, the code flushes the whole TLB unconditionally. Otherwise, 164 for positive values of it, the kernel will use single TLB entry 165 invalidating instructions according to the following formula: 166 167 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift 168 169 If in doubt, say "N". 170 171config IOMMU_DEBUG 172 bool "Enable IOMMU debugging" 173 depends on GART_IOMMU && DEBUG_KERNEL 174 depends on X86_64 175 ---help--- 176 Force the IOMMU to on even when you have less than 4GB of 177 memory and add debugging code. On overflow always panic. And 178 allow to enable IOMMU leak tracing. Can be disabled at boot 179 time with iommu=noforce. This will also enable scatter gather 180 list merging. Currently not recommended for production 181 code. When you use it make sure you have a big enough 182 IOMMU/AGP aperture. Most of the options enabled by this can 183 be set more finegrained using the iommu= command line 184 options. See Documentation/x86/x86_64/boot-options.txt for more 185 details. 186 187config IOMMU_STRESS 188 bool "Enable IOMMU stress-test mode" 189 ---help--- 190 This option disables various optimizations in IOMMU related 191 code to do real stress testing of the IOMMU code. This option 192 will cause a performance drop and should only be enabled for 193 testing. 194 195config IOMMU_LEAK 196 bool "IOMMU leak tracing" 197 depends on IOMMU_DEBUG && DMA_API_DEBUG 198 ---help--- 199 Add a simple leak tracer to the IOMMU code. This is useful when you 200 are debugging a buggy device driver that leaks IOMMU mappings. 201 202config HAVE_MMIOTRACE_SUPPORT 203 def_bool y 204 205config X86_DECODER_SELFTEST 206 bool "x86 instruction decoder selftest" 207 depends on DEBUG_KERNEL && KPROBES 208 depends on !COMPILE_TEST 209 ---help--- 210 Perform x86 instruction decoder selftests at build time. 211 This option is useful for checking the sanity of x86 instruction 212 decoder code. 213 If unsure, say "N". 214 215# 216# IO delay types: 217# 218 219config IO_DELAY_TYPE_0X80 220 int 221 default "0" 222 223config IO_DELAY_TYPE_0XED 224 int 225 default "1" 226 227config IO_DELAY_TYPE_UDELAY 228 int 229 default "2" 230 231config IO_DELAY_TYPE_NONE 232 int 233 default "3" 234 235choice 236 prompt "IO delay type" 237 default IO_DELAY_0X80 238 239config IO_DELAY_0X80 240 bool "port 0x80 based port-IO delay [recommended]" 241 ---help--- 242 This is the traditional Linux IO delay used for in/out_p. 243 It is the most tested hence safest selection here. 244 245config IO_DELAY_0XED 246 bool "port 0xed based port-IO delay" 247 ---help--- 248 Use port 0xed as the IO delay. This frees up port 0x80 which is 249 often used as a hardware-debug port. 250 251config IO_DELAY_UDELAY 252 bool "udelay based port-IO delay" 253 ---help--- 254 Use udelay(2) as the IO delay method. This provides the delay 255 while not having any side-effect on the IO port space. 256 257config IO_DELAY_NONE 258 bool "no port-IO delay" 259 ---help--- 260 No port-IO delay. Will break on old boxes that require port-IO 261 delay for certain operations. Should work on most new machines. 262 263endchoice 264 265if IO_DELAY_0X80 266config DEFAULT_IO_DELAY_TYPE 267 int 268 default IO_DELAY_TYPE_0X80 269endif 270 271if IO_DELAY_0XED 272config DEFAULT_IO_DELAY_TYPE 273 int 274 default IO_DELAY_TYPE_0XED 275endif 276 277if IO_DELAY_UDELAY 278config DEFAULT_IO_DELAY_TYPE 279 int 280 default IO_DELAY_TYPE_UDELAY 281endif 282 283if IO_DELAY_NONE 284config DEFAULT_IO_DELAY_TYPE 285 int 286 default IO_DELAY_TYPE_NONE 287endif 288 289config DEBUG_BOOT_PARAMS 290 bool "Debug boot parameters" 291 depends on DEBUG_KERNEL 292 depends on DEBUG_FS 293 ---help--- 294 This option will cause struct boot_params to be exported via debugfs. 295 296config CPA_DEBUG 297 bool "CPA self-test code" 298 depends on DEBUG_KERNEL 299 ---help--- 300 Do change_page_attr() self-tests every 30 seconds. 301 302config OPTIMIZE_INLINING 303 bool "Allow gcc to uninline functions marked 'inline'" 304 ---help--- 305 This option determines if the kernel forces gcc to inline the functions 306 developers have marked 'inline'. Doing so takes away freedom from gcc to 307 do what it thinks is best, which is desirable for the gcc 3.x series of 308 compilers. The gcc 4.x series have a rewritten inlining algorithm and 309 enabling this option will generate a smaller kernel there. Hopefully 310 this algorithm is so good that allowing gcc 4.x and above to make the 311 decision will become the default in the future. Until then this option 312 is there to test gcc for this. 313 314 If unsure, say N. 315 316config DEBUG_ENTRY 317 bool "Debug low-level entry code" 318 depends on DEBUG_KERNEL 319 ---help--- 320 This option enables sanity checks in x86's low-level entry code. 321 Some of these sanity checks may slow down kernel entries and 322 exits or otherwise impact performance. 323 324 This is currently used to help test NMI code. 325 326 If unsure, say N. 327 328config DEBUG_NMI_SELFTEST 329 bool "NMI Selftest" 330 depends on DEBUG_KERNEL && X86_LOCAL_APIC 331 ---help--- 332 Enabling this option turns on a quick NMI selftest to verify 333 that the NMI behaves correctly. 334 335 This might help diagnose strange hangs that rely on NMI to 336 function properly. 337 338 If unsure, say N. 339 340config DEBUG_IMR_SELFTEST 341 bool "Isolated Memory Region self test" 342 default n 343 depends on INTEL_IMR 344 ---help--- 345 This option enables automated sanity testing of the IMR code. 346 Some simple tests are run to verify IMR bounds checking, alignment 347 and overlapping. This option is really only useful if you are 348 debugging an IMR memory map or are modifying the IMR code and want to 349 test your changes. 350 351 If unsure say N here. 352 353config X86_DEBUG_STATIC_CPU_HAS 354 bool "Debug alternatives" 355 depends on DEBUG_KERNEL 356 ---help--- 357 This option causes additional code to be generated which 358 fails if static_cpu_has() is used before alternatives have 359 run. 360 361 If unsure, say N. 362 363config X86_DEBUG_FPU 364 bool "Debug the x86 FPU code" 365 depends on DEBUG_KERNEL 366 default y 367 ---help--- 368 If this option is enabled then there will be extra sanity 369 checks and (boot time) debug printouts added to the kernel. 370 This debugging adds some small amount of runtime overhead 371 to the kernel. 372 373 If unsure, say N. 374 375config PUNIT_ATOM_DEBUG 376 tristate "ATOM Punit debug driver" 377 select DEBUG_FS 378 select IOSF_MBI 379 ---help--- 380 This is a debug driver, which gets the power states 381 of all Punit North Complex devices. The power states of 382 each device is exposed as part of the debugfs interface. 383 The current power state can be read from 384 /sys/kernel/debug/punit_atom/dev_power_state 385 386endmenu 387