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