1# SPDX-License-Identifier: GPL-2.0 2 3config EARLY_PRINTK_USB 4 bool 5 6config X86_VERBOSE_BOOTUP 7 bool "Enable verbose x86 bootup info messages" 8 default y 9 help 10 Enables the informational output from the decompression stage 11 (e.g. bzImage) of the boot. If you disable this you will still 12 see errors. Disable this if you want silent bootup. 13 14config EARLY_PRINTK 15 bool "Early printk" if EXPERT 16 default y 17 help 18 Write kernel log output directly into the VGA buffer or to a serial 19 port. 20 21 This is useful for kernel debugging when your machine crashes very 22 early before the console code is initialized. For normal operation 23 it is not recommended because it looks ugly and doesn't cooperate 24 with klogd/syslogd or the X server. You should normally say N here, 25 unless you want to debug such a crash. 26 27config EARLY_PRINTK_DBGP 28 bool "Early printk via EHCI debug port" 29 depends on EARLY_PRINTK && PCI 30 select EARLY_PRINTK_USB 31 help 32 Write kernel log output directly into the EHCI debug port. 33 34 This is useful for kernel debugging when your machine crashes very 35 early before the console code is initialized. For normal operation 36 it is not recommended because it looks ugly and doesn't cooperate 37 with klogd/syslogd or the X server. You should normally say N here, 38 unless you want to debug such a crash. You need usb debug device. 39 40config EARLY_PRINTK_USB_XDBC 41 bool "Early printk via the xHCI debug port" 42 depends on EARLY_PRINTK && PCI 43 select EARLY_PRINTK_USB 44 help 45 Write kernel log output directly into the xHCI debug port. 46 47 One use for this feature is kernel debugging, for example when your 48 machine crashes very early before the regular console code is 49 initialized. Other uses include simpler, lockless logging instead of 50 a full-blown printk console driver + klogd. 51 52 For normal production environments this is normally not recommended, 53 because it doesn't feed events into klogd/syslogd and doesn't try to 54 print anything on the screen. 55 56 You should normally say N here, unless you want to debug early 57 crashes or need a very simple printk logging facility. 58 59config EFI_PGT_DUMP 60 bool "Dump the EFI pagetable" 61 depends on EFI 62 select PTDUMP_CORE 63 help 64 Enable this if you want to dump the EFI page table before 65 enabling virtual mode. This can be used to debug miscellaneous 66 issues with the mapping of the EFI runtime regions into that 67 table. 68 69config DEBUG_TLBFLUSH 70 bool "Set upper limit of TLB entries to flush one-by-one" 71 depends on DEBUG_KERNEL 72 help 73 74 X86-only for now. 75 76 This option allows the user to tune the amount of TLB entries the 77 kernel flushes one-by-one instead of doing a full TLB flush. In 78 certain situations, the former is cheaper. This is controlled by the 79 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it 80 to -1, the code flushes the whole TLB unconditionally. Otherwise, 81 for positive values of it, the kernel will use single TLB entry 82 invalidating instructions according to the following formula: 83 84 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift 85 86 If in doubt, say "N". 87 88config IOMMU_DEBUG 89 bool "Enable IOMMU debugging" 90 depends on GART_IOMMU && DEBUG_KERNEL 91 depends on X86_64 92 help 93 Force the IOMMU to on even when you have less than 4GB of 94 memory and add debugging code. On overflow always panic. And 95 allow to enable IOMMU leak tracing. Can be disabled at boot 96 time with iommu=noforce. This will also enable scatter gather 97 list merging. Currently not recommended for production 98 code. When you use it make sure you have a big enough 99 IOMMU/AGP aperture. Most of the options enabled by this can 100 be set more finegrained using the iommu= command line 101 options. See Documentation/x86/x86_64/boot-options.rst for more 102 details. 103 104config IOMMU_LEAK 105 bool "IOMMU leak tracing" 106 depends on IOMMU_DEBUG && DMA_API_DEBUG 107 help 108 Add a simple leak tracer to the IOMMU code. This is useful when you 109 are debugging a buggy device driver that leaks IOMMU mappings. 110 111config HAVE_MMIOTRACE_SUPPORT 112 def_bool y 113 114config X86_DECODER_SELFTEST 115 bool "x86 instruction decoder selftest" 116 depends on DEBUG_KERNEL && INSTRUCTION_DECODER 117 depends on !COMPILE_TEST 118 help 119 Perform x86 instruction decoder selftests at build time. 120 This option is useful for checking the sanity of x86 instruction 121 decoder code. 122 If unsure, say "N". 123 124choice 125 prompt "IO delay type" 126 default IO_DELAY_0X80 127 128config IO_DELAY_0X80 129 bool "port 0x80 based port-IO delay [recommended]" 130 help 131 This is the traditional Linux IO delay used for in/out_p. 132 It is the most tested hence safest selection here. 133 134config IO_DELAY_0XED 135 bool "port 0xed based port-IO delay" 136 help 137 Use port 0xed as the IO delay. This frees up port 0x80 which is 138 often used as a hardware-debug port. 139 140config IO_DELAY_UDELAY 141 bool "udelay based port-IO delay" 142 help 143 Use udelay(2) as the IO delay method. This provides the delay 144 while not having any side-effect on the IO port space. 145 146config IO_DELAY_NONE 147 bool "no port-IO delay" 148 help 149 No port-IO delay. Will break on old boxes that require port-IO 150 delay for certain operations. Should work on most new machines. 151 152endchoice 153 154config DEBUG_BOOT_PARAMS 155 bool "Debug boot parameters" 156 depends on DEBUG_KERNEL 157 depends on DEBUG_FS 158 help 159 This option will cause struct boot_params to be exported via debugfs. 160 161config CPA_DEBUG 162 bool "CPA self-test code" 163 depends on DEBUG_KERNEL 164 help 165 Do change_page_attr() self-tests every 30 seconds. 166 167config DEBUG_ENTRY 168 bool "Debug low-level entry code" 169 depends on DEBUG_KERNEL 170 help 171 This option enables sanity checks in x86's low-level entry code. 172 Some of these sanity checks may slow down kernel entries and 173 exits or otherwise impact performance. 174 175 If unsure, say N. 176 177config DEBUG_NMI_SELFTEST 178 bool "NMI Selftest" 179 depends on DEBUG_KERNEL && X86_LOCAL_APIC 180 help 181 Enabling this option turns on a quick NMI selftest to verify 182 that the NMI behaves correctly. 183 184 This might help diagnose strange hangs that rely on NMI to 185 function properly. 186 187 If unsure, say N. 188 189config DEBUG_IMR_SELFTEST 190 bool "Isolated Memory Region self test" 191 depends on INTEL_IMR 192 help 193 This option enables automated sanity testing of the IMR code. 194 Some simple tests are run to verify IMR bounds checking, alignment 195 and overlapping. This option is really only useful if you are 196 debugging an IMR memory map or are modifying the IMR code and want to 197 test your changes. 198 199 If unsure say N here. 200 201config X86_DEBUG_FPU 202 bool "Debug the x86 FPU code" 203 depends on DEBUG_KERNEL 204 default y 205 help 206 If this option is enabled then there will be extra sanity 207 checks and (boot time) debug printouts added to the kernel. 208 This debugging adds some small amount of runtime overhead 209 to the kernel. 210 211 If unsure, say N. 212 213config PUNIT_ATOM_DEBUG 214 tristate "ATOM Punit debug driver" 215 depends on PCI 216 select DEBUG_FS 217 select IOSF_MBI 218 help 219 This is a debug driver, which gets the power states 220 of all Punit North Complex devices. The power states of 221 each device is exposed as part of the debugfs interface. 222 The current power state can be read from 223 /sys/kernel/debug/punit_atom/dev_power_state 224 225choice 226 prompt "Choose kernel unwinder" 227 default UNWINDER_ORC if X86_64 228 default UNWINDER_FRAME_POINTER if X86_32 229 help 230 This determines which method will be used for unwinding kernel stack 231 traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack, 232 livepatch, lockdep, and more. 233 234config UNWINDER_ORC 235 bool "ORC unwinder" 236 depends on X86_64 237 select STACK_VALIDATION 238 help 239 This option enables the ORC (Oops Rewind Capability) unwinder for 240 unwinding kernel stack traces. It uses a custom data format which is 241 a simplified version of the DWARF Call Frame Information standard. 242 243 This unwinder is more accurate across interrupt entry frames than the 244 frame pointer unwinder. It also enables a 5-10% performance 245 improvement across the entire kernel compared to frame pointers. 246 247 Enabling this option will increase the kernel's runtime memory usage 248 by roughly 2-4MB, depending on your kernel config. 249 250config UNWINDER_FRAME_POINTER 251 bool "Frame pointer unwinder" 252 select FRAME_POINTER 253 help 254 This option enables the frame pointer unwinder for unwinding kernel 255 stack traces. 256 257 The unwinder itself is fast and it uses less RAM than the ORC 258 unwinder, but the kernel text size will grow by ~3% and the kernel's 259 overall performance will degrade by roughly 5-10%. 260 261config UNWINDER_GUESS 262 bool "Guess unwinder" 263 depends on EXPERT 264 depends on !STACKDEPOT 265 help 266 This option enables the "guess" unwinder for unwinding kernel stack 267 traces. It scans the stack and reports every kernel text address it 268 finds. Some of the addresses it reports may be incorrect. 269 270 While this option often produces false positives, it can still be 271 useful in many cases. Unlike the other unwinders, it has no runtime 272 overhead. 273 274endchoice 275 276config FRAME_POINTER 277 depends on !UNWINDER_ORC && !UNWINDER_GUESS 278 bool 279