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 EFI_PGT_DUMP 66 bool "Dump the EFI pagetable" 67 depends on EFI 68 select PTDUMP_CORE 69 ---help--- 70 Enable this if you want to dump the EFI page table before 71 enabling virtual mode. This can be used to debug miscellaneous 72 issues with the mapping of the EFI runtime regions into that 73 table. 74 75config DEBUG_WX 76 bool "Warn on W+X mappings at boot" 77 select PTDUMP_CORE 78 ---help--- 79 Generate a warning if any W+X mappings are found at boot. 80 81 This is useful for discovering cases where the kernel is leaving 82 W+X mappings after applying NX, as such mappings are a security risk. 83 84 Look for a message in dmesg output like this: 85 86 x86/mm: Checked W+X mappings: passed, no W+X pages found. 87 88 or like this, if the check failed: 89 90 x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found. 91 92 Note that even if the check fails, your kernel is possibly 93 still fine, as W+X mappings are not a security hole in 94 themselves, what they do is that they make the exploitation 95 of other unfixed kernel bugs easier. 96 97 There is no runtime or memory usage effect of this option 98 once the kernel has booted up - it's a one time check. 99 100 If in doubt, say "Y". 101 102config DOUBLEFAULT 103 default y 104 bool "Enable doublefault exception handler" if EXPERT && X86_32 105 ---help--- 106 This option allows trapping of rare doublefault exceptions that 107 would otherwise cause a system to silently reboot. Disabling this 108 option saves about 4k and might cause you much additional grey 109 hair. 110 111config DEBUG_TLBFLUSH 112 bool "Set upper limit of TLB entries to flush one-by-one" 113 depends on DEBUG_KERNEL 114 ---help--- 115 116 X86-only for now. 117 118 This option allows the user to tune the amount of TLB entries the 119 kernel flushes one-by-one instead of doing a full TLB flush. In 120 certain situations, the former is cheaper. This is controlled by the 121 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it 122 to -1, the code flushes the whole TLB unconditionally. Otherwise, 123 for positive values of it, the kernel will use single TLB entry 124 invalidating instructions according to the following formula: 125 126 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift 127 128 If in doubt, say "N". 129 130config IOMMU_DEBUG 131 bool "Enable IOMMU debugging" 132 depends on GART_IOMMU && DEBUG_KERNEL 133 depends on X86_64 134 ---help--- 135 Force the IOMMU to on even when you have less than 4GB of 136 memory and add debugging code. On overflow always panic. And 137 allow to enable IOMMU leak tracing. Can be disabled at boot 138 time with iommu=noforce. This will also enable scatter gather 139 list merging. Currently not recommended for production 140 code. When you use it make sure you have a big enough 141 IOMMU/AGP aperture. Most of the options enabled by this can 142 be set more finegrained using the iommu= command line 143 options. See Documentation/x86/x86_64/boot-options.rst for more 144 details. 145 146config IOMMU_LEAK 147 bool "IOMMU leak tracing" 148 depends on IOMMU_DEBUG && DMA_API_DEBUG 149 ---help--- 150 Add a simple leak tracer to the IOMMU code. This is useful when you 151 are debugging a buggy device driver that leaks IOMMU mappings. 152 153config HAVE_MMIOTRACE_SUPPORT 154 def_bool y 155 156config X86_DECODER_SELFTEST 157 bool "x86 instruction decoder selftest" 158 depends on DEBUG_KERNEL && INSTRUCTION_DECODER 159 depends on !COMPILE_TEST 160 ---help--- 161 Perform x86 instruction decoder selftests at build time. 162 This option is useful for checking the sanity of x86 instruction 163 decoder code. 164 If unsure, say "N". 165 166choice 167 prompt "IO delay type" 168 default IO_DELAY_0X80 169 170config IO_DELAY_0X80 171 bool "port 0x80 based port-IO delay [recommended]" 172 ---help--- 173 This is the traditional Linux IO delay used for in/out_p. 174 It is the most tested hence safest selection here. 175 176config IO_DELAY_0XED 177 bool "port 0xed based port-IO delay" 178 ---help--- 179 Use port 0xed as the IO delay. This frees up port 0x80 which is 180 often used as a hardware-debug port. 181 182config IO_DELAY_UDELAY 183 bool "udelay based port-IO delay" 184 ---help--- 185 Use udelay(2) as the IO delay method. This provides the delay 186 while not having any side-effect on the IO port space. 187 188config IO_DELAY_NONE 189 bool "no port-IO delay" 190 ---help--- 191 No port-IO delay. Will break on old boxes that require port-IO 192 delay for certain operations. Should work on most new machines. 193 194endchoice 195 196config DEBUG_BOOT_PARAMS 197 bool "Debug boot parameters" 198 depends on DEBUG_KERNEL 199 depends on DEBUG_FS 200 ---help--- 201 This option will cause struct boot_params to be exported via debugfs. 202 203config CPA_DEBUG 204 bool "CPA self-test code" 205 depends on DEBUG_KERNEL 206 ---help--- 207 Do change_page_attr() self-tests every 30 seconds. 208 209config DEBUG_ENTRY 210 bool "Debug low-level entry code" 211 depends on DEBUG_KERNEL 212 ---help--- 213 This option enables sanity checks in x86's low-level entry code. 214 Some of these sanity checks may slow down kernel entries and 215 exits or otherwise impact performance. 216 217 If unsure, say N. 218 219config DEBUG_NMI_SELFTEST 220 bool "NMI Selftest" 221 depends on DEBUG_KERNEL && X86_LOCAL_APIC 222 ---help--- 223 Enabling this option turns on a quick NMI selftest to verify 224 that the NMI behaves correctly. 225 226 This might help diagnose strange hangs that rely on NMI to 227 function properly. 228 229 If unsure, say N. 230 231config DEBUG_IMR_SELFTEST 232 bool "Isolated Memory Region self test" 233 depends on INTEL_IMR 234 ---help--- 235 This option enables automated sanity testing of the IMR code. 236 Some simple tests are run to verify IMR bounds checking, alignment 237 and overlapping. This option is really only useful if you are 238 debugging an IMR memory map or are modifying the IMR code and want to 239 test your changes. 240 241 If unsure say N here. 242 243config X86_DEBUG_FPU 244 bool "Debug the x86 FPU code" 245 depends on DEBUG_KERNEL 246 default y 247 ---help--- 248 If this option is enabled then there will be extra sanity 249 checks and (boot time) debug printouts added to the kernel. 250 This debugging adds some small amount of runtime overhead 251 to the kernel. 252 253 If unsure, say N. 254 255config PUNIT_ATOM_DEBUG 256 tristate "ATOM Punit debug driver" 257 depends on PCI 258 select DEBUG_FS 259 select IOSF_MBI 260 ---help--- 261 This is a debug driver, which gets the power states 262 of all Punit North Complex devices. The power states of 263 each device is exposed as part of the debugfs interface. 264 The current power state can be read from 265 /sys/kernel/debug/punit_atom/dev_power_state 266 267choice 268 prompt "Choose kernel unwinder" 269 default UNWINDER_ORC if X86_64 270 default UNWINDER_FRAME_POINTER if X86_32 271 ---help--- 272 This determines which method will be used for unwinding kernel stack 273 traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack, 274 livepatch, lockdep, and more. 275 276config UNWINDER_ORC 277 bool "ORC unwinder" 278 depends on X86_64 279 select STACK_VALIDATION 280 ---help--- 281 This option enables the ORC (Oops Rewind Capability) unwinder for 282 unwinding kernel stack traces. It uses a custom data format which is 283 a simplified version of the DWARF Call Frame Information standard. 284 285 This unwinder is more accurate across interrupt entry frames than the 286 frame pointer unwinder. It also enables a 5-10% performance 287 improvement across the entire kernel compared to frame pointers. 288 289 Enabling this option will increase the kernel's runtime memory usage 290 by roughly 2-4MB, depending on your kernel config. 291 292config UNWINDER_FRAME_POINTER 293 bool "Frame pointer unwinder" 294 select FRAME_POINTER 295 ---help--- 296 This option enables the frame pointer unwinder for unwinding kernel 297 stack traces. 298 299 The unwinder itself is fast and it uses less RAM than the ORC 300 unwinder, but the kernel text size will grow by ~3% and the kernel's 301 overall performance will degrade by roughly 5-10%. 302 303config UNWINDER_GUESS 304 bool "Guess unwinder" 305 depends on EXPERT 306 depends on !STACKDEPOT 307 ---help--- 308 This option enables the "guess" unwinder for unwinding kernel stack 309 traces. It scans the stack and reports every kernel text address it 310 finds. Some of the addresses it reports may be incorrect. 311 312 While this option often produces false positives, it can still be 313 useful in many cases. Unlike the other unwinders, it has no runtime 314 overhead. 315 316endchoice 317 318config FRAME_POINTER 319 depends on !UNWINDER_ORC && !UNWINDER_GUESS 320 bool 321