1# SPDX-License-Identifier: GPL-2.0 2 3config TRACE_IRQFLAGS_SUPPORT 4 def_bool y 5 6config EARLY_PRINTK_USB 7 bool 8 9config X86_VERBOSE_BOOTUP 10 bool "Enable verbose x86 bootup info messages" 11 default y 12 ---help--- 13 Enables the informational output from the decompression stage 14 (e.g. bzImage) of the boot. If you disable this you will still 15 see errors. Disable this if you want silent bootup. 16 17config EARLY_PRINTK 18 bool "Early printk" if EXPERT 19 default y 20 ---help--- 21 Write kernel log output directly into the VGA buffer or to a serial 22 port. 23 24 This is useful for kernel debugging when your machine crashes very 25 early before the console code is initialized. For normal operation 26 it is not recommended because it looks ugly and doesn't cooperate 27 with klogd/syslogd or the X server. You should normally say N here, 28 unless you want to debug such a crash. 29 30config EARLY_PRINTK_DBGP 31 bool "Early printk via EHCI debug port" 32 depends on EARLY_PRINTK && PCI 33 select EARLY_PRINTK_USB 34 ---help--- 35 Write kernel log output directly into the EHCI debug port. 36 37 This is useful for kernel debugging when your machine crashes very 38 early before the console code is initialized. For normal operation 39 it is not recommended because it looks ugly and doesn't cooperate 40 with klogd/syslogd or the X server. You should normally say N here, 41 unless you want to debug such a crash. You need usb debug device. 42 43config EARLY_PRINTK_USB_XDBC 44 bool "Early printk via the xHCI debug port" 45 depends on EARLY_PRINTK && PCI 46 select EARLY_PRINTK_USB 47 ---help--- 48 Write kernel log output directly into the xHCI debug port. 49 50 One use for this feature is kernel debugging, for example when your 51 machine crashes very early before the regular console code is 52 initialized. Other uses include simpler, lockless logging instead of 53 a full-blown printk console driver + klogd. 54 55 For normal production environments this is normally not recommended, 56 because it doesn't feed events into klogd/syslogd and doesn't try to 57 print anything on the screen. 58 59 You should normally say N here, unless you want to debug early 60 crashes or need a very simple printk logging facility. 61 62config MCSAFE_TEST 63 def_bool n 64 65config X86_PTDUMP_CORE 66 def_bool n 67 68config X86_PTDUMP 69 tristate "Export kernel pagetable layout to userspace via debugfs" 70 depends on DEBUG_KERNEL 71 select DEBUG_FS 72 select X86_PTDUMP_CORE 73 ---help--- 74 Say Y here if you want to show the kernel pagetable layout in a 75 debugfs file. This information is only useful for kernel developers 76 who are working in architecture specific areas of the kernel. 77 It is probably not a good idea to enable this feature in a production 78 kernel. 79 If in doubt, say "N" 80 81config EFI_PGT_DUMP 82 bool "Dump the EFI pagetable" 83 depends on EFI 84 select X86_PTDUMP_CORE 85 ---help--- 86 Enable this if you want to dump the EFI page table before 87 enabling virtual mode. This can be used to debug miscellaneous 88 issues with the mapping of the EFI runtime regions into that 89 table. 90 91config DEBUG_WX 92 bool "Warn on W+X mappings at boot" 93 select X86_PTDUMP_CORE 94 ---help--- 95 Generate a warning if any W+X mappings are found at boot. 96 97 This is useful for discovering cases where the kernel is leaving 98 W+X mappings after applying NX, as such mappings are a security risk. 99 100 Look for a message in dmesg output like this: 101 102 x86/mm: Checked W+X mappings: passed, no W+X pages found. 103 104 or like this, if the check failed: 105 106 x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found. 107 108 Note that even if the check fails, your kernel is possibly 109 still fine, as W+X mappings are not a security hole in 110 themselves, what they do is that they make the exploitation 111 of other unfixed kernel bugs easier. 112 113 There is no runtime or memory usage effect of this option 114 once the kernel has booted up - it's a one time check. 115 116 If in doubt, say "Y". 117 118config DOUBLEFAULT 119 default y 120 bool "Enable doublefault exception handler" if EXPERT 121 ---help--- 122 This option allows trapping of rare doublefault exceptions that 123 would otherwise cause a system to silently reboot. Disabling this 124 option saves about 4k and might cause you much additional grey 125 hair. 126 127config DEBUG_TLBFLUSH 128 bool "Set upper limit of TLB entries to flush one-by-one" 129 depends on DEBUG_KERNEL 130 ---help--- 131 132 X86-only for now. 133 134 This option allows the user to tune the amount of TLB entries the 135 kernel flushes one-by-one instead of doing a full TLB flush. In 136 certain situations, the former is cheaper. This is controlled by the 137 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it 138 to -1, the code flushes the whole TLB unconditionally. Otherwise, 139 for positive values of it, the kernel will use single TLB entry 140 invalidating instructions according to the following formula: 141 142 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift 143 144 If in doubt, say "N". 145 146config IOMMU_DEBUG 147 bool "Enable IOMMU debugging" 148 depends on GART_IOMMU && DEBUG_KERNEL 149 depends on X86_64 150 ---help--- 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/x86_64/boot-options.rst for more 160 details. 161 162config IOMMU_LEAK 163 bool "IOMMU leak tracing" 164 depends on IOMMU_DEBUG && DMA_API_DEBUG 165 ---help--- 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 169config HAVE_MMIOTRACE_SUPPORT 170 def_bool y 171 172config X86_DECODER_SELFTEST 173 bool "x86 instruction decoder selftest" 174 depends on DEBUG_KERNEL && INSTRUCTION_DECODER 175 depends on !COMPILE_TEST 176 ---help--- 177 Perform x86 instruction decoder selftests at build time. 178 This option is useful for checking the sanity of x86 instruction 179 decoder code. 180 If unsure, say "N". 181 182choice 183 prompt "IO delay type" 184 default IO_DELAY_0X80 185 186config IO_DELAY_0X80 187 bool "port 0x80 based port-IO delay [recommended]" 188 ---help--- 189 This is the traditional Linux IO delay used for in/out_p. 190 It is the most tested hence safest selection here. 191 192config IO_DELAY_0XED 193 bool "port 0xed based port-IO delay" 194 ---help--- 195 Use port 0xed as the IO delay. This frees up port 0x80 which is 196 often used as a hardware-debug port. 197 198config IO_DELAY_UDELAY 199 bool "udelay based port-IO delay" 200 ---help--- 201 Use udelay(2) as the IO delay method. This provides the delay 202 while not having any side-effect on the IO port space. 203 204config IO_DELAY_NONE 205 bool "no port-IO delay" 206 ---help--- 207 No port-IO delay. Will break on old boxes that require port-IO 208 delay for certain operations. Should work on most new machines. 209 210endchoice 211 212config DEBUG_BOOT_PARAMS 213 bool "Debug boot parameters" 214 depends on DEBUG_KERNEL 215 depends on DEBUG_FS 216 ---help--- 217 This option will cause struct boot_params to be exported via debugfs. 218 219config CPA_DEBUG 220 bool "CPA self-test code" 221 depends on DEBUG_KERNEL 222 ---help--- 223 Do change_page_attr() self-tests every 30 seconds. 224 225config DEBUG_ENTRY 226 bool "Debug low-level entry code" 227 depends on DEBUG_KERNEL 228 ---help--- 229 This option enables sanity checks in x86's low-level entry code. 230 Some of these sanity checks may slow down kernel entries and 231 exits or otherwise impact performance. 232 233 If unsure, say N. 234 235config DEBUG_NMI_SELFTEST 236 bool "NMI Selftest" 237 depends on DEBUG_KERNEL && X86_LOCAL_APIC 238 ---help--- 239 Enabling this option turns on a quick NMI selftest to verify 240 that the NMI behaves correctly. 241 242 This might help diagnose strange hangs that rely on NMI to 243 function properly. 244 245 If unsure, say N. 246 247config DEBUG_IMR_SELFTEST 248 bool "Isolated Memory Region self test" 249 depends on INTEL_IMR 250 ---help--- 251 This option enables automated sanity testing of the IMR code. 252 Some simple tests are run to verify IMR bounds checking, alignment 253 and overlapping. This option is really only useful if you are 254 debugging an IMR memory map or are modifying the IMR code and want to 255 test your changes. 256 257 If unsure say N here. 258 259config X86_DEBUG_FPU 260 bool "Debug the x86 FPU code" 261 depends on DEBUG_KERNEL 262 default y 263 ---help--- 264 If this option is enabled then there will be extra sanity 265 checks and (boot time) debug printouts added to the kernel. 266 This debugging adds some small amount of runtime overhead 267 to the kernel. 268 269 If unsure, say N. 270 271config PUNIT_ATOM_DEBUG 272 tristate "ATOM Punit debug driver" 273 depends on PCI 274 select DEBUG_FS 275 select IOSF_MBI 276 ---help--- 277 This is a debug driver, which gets the power states 278 of all Punit North Complex devices. The power states of 279 each device is exposed as part of the debugfs interface. 280 The current power state can be read from 281 /sys/kernel/debug/punit_atom/dev_power_state 282 283choice 284 prompt "Choose kernel unwinder" 285 default UNWINDER_ORC if X86_64 286 default UNWINDER_FRAME_POINTER if X86_32 287 ---help--- 288 This determines which method will be used for unwinding kernel stack 289 traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack, 290 livepatch, lockdep, and more. 291 292config UNWINDER_ORC 293 bool "ORC unwinder" 294 depends on X86_64 295 select STACK_VALIDATION 296 ---help--- 297 This option enables the ORC (Oops Rewind Capability) unwinder for 298 unwinding kernel stack traces. It uses a custom data format which is 299 a simplified version of the DWARF Call Frame Information standard. 300 301 This unwinder is more accurate across interrupt entry frames than the 302 frame pointer unwinder. It also enables a 5-10% performance 303 improvement across the entire kernel compared to frame pointers. 304 305 Enabling this option will increase the kernel's runtime memory usage 306 by roughly 2-4MB, depending on your kernel config. 307 308config UNWINDER_FRAME_POINTER 309 bool "Frame pointer unwinder" 310 select FRAME_POINTER 311 ---help--- 312 This option enables the frame pointer unwinder for unwinding kernel 313 stack traces. 314 315 The unwinder itself is fast and it uses less RAM than the ORC 316 unwinder, but the kernel text size will grow by ~3% and the kernel's 317 overall performance will degrade by roughly 5-10%. 318 319 This option is recommended if you want to use the livepatch 320 consistency model, as this is currently the only way to get a 321 reliable stack trace (CONFIG_HAVE_RELIABLE_STACKTRACE). 322 323config UNWINDER_GUESS 324 bool "Guess unwinder" 325 depends on EXPERT 326 depends on !STACKDEPOT 327 ---help--- 328 This option enables the "guess" unwinder for unwinding kernel stack 329 traces. It scans the stack and reports every kernel text address it 330 finds. Some of the addresses it reports may be incorrect. 331 332 While this option often produces false positives, it can still be 333 useful in many cases. Unlike the other unwinders, it has no runtime 334 overhead. 335 336endchoice 337 338config FRAME_POINTER 339 depends on !UNWINDER_ORC && !UNWINDER_GUESS 340 bool 341
