1# SPDX-License-Identifier: GPL-2.0 2 3config TRACE_IRQFLAGS_NMI_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 EFI_PGT_DUMP 63 bool "Dump the EFI pagetable" 64 depends on EFI 65 select PTDUMP_CORE 66 help 67 Enable this if you want to dump the EFI page table before 68 enabling virtual mode. This can be used to debug miscellaneous 69 issues with the mapping of the EFI runtime regions into that 70 table. 71 72config DEBUG_TLBFLUSH 73 bool "Set upper limit of TLB entries to flush one-by-one" 74 depends on DEBUG_KERNEL 75 help 76 X86-only for now. 77 78 This option allows the user to tune the amount of TLB entries the 79 kernel flushes one-by-one instead of doing a full TLB flush. In 80 certain situations, the former is cheaper. This is controlled by the 81 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it 82 to -1, the code flushes the whole TLB unconditionally. Otherwise, 83 for positive values of it, the kernel will use single TLB entry 84 invalidating instructions according to the following formula: 85 86 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift 87 88 If in doubt, say "N". 89 90config IOMMU_DEBUG 91 bool "Enable IOMMU debugging" 92 depends on GART_IOMMU && DEBUG_KERNEL 93 depends on X86_64 94 help 95 Force the IOMMU to on even when you have less than 4GB of 96 memory and add debugging code. On overflow always panic. And 97 allow to enable IOMMU leak tracing. Can be disabled at boot 98 time with iommu=noforce. This will also enable scatter gather 99 list merging. Currently not recommended for production 100 code. When you use it make sure you have a big enough 101 IOMMU/AGP aperture. Most of the options enabled by this can 102 be set more finegrained using the iommu= command line 103 options. See Documentation/x86/x86_64/boot-options.rst for more 104 details. 105 106config IOMMU_LEAK 107 bool "IOMMU leak tracing" 108 depends on IOMMU_DEBUG && DMA_API_DEBUG 109 help 110 Add a simple leak tracer to the IOMMU code. This is useful when you 111 are debugging a buggy device driver that leaks IOMMU mappings. 112 113config HAVE_MMIOTRACE_SUPPORT 114 def_bool y 115 116config X86_DECODER_SELFTEST 117 bool "x86 instruction decoder selftest" 118 depends on DEBUG_KERNEL && INSTRUCTION_DECODER 119 depends on !COMPILE_TEST 120 help 121 Perform x86 instruction decoder selftests at build time. 122 This option is useful for checking the sanity of x86 instruction 123 decoder code. 124 If unsure, say "N". 125 126choice 127 prompt "IO delay type" 128 default IO_DELAY_0X80 129 130config IO_DELAY_0X80 131 bool "port 0x80 based port-IO delay [recommended]" 132 help 133 This is the traditional Linux IO delay used for in/out_p. 134 It is the most tested hence safest selection here. 135 136config IO_DELAY_0XED 137 bool "port 0xed based port-IO delay" 138 help 139 Use port 0xed as the IO delay. This frees up port 0x80 which is 140 often used as a hardware-debug port. 141 142config IO_DELAY_UDELAY 143 bool "udelay based port-IO delay" 144 help 145 Use udelay(2) as the IO delay method. This provides the delay 146 while not having any side-effect on the IO port space. 147 148config IO_DELAY_NONE 149 bool "no port-IO delay" 150 help 151 No port-IO delay. Will break on old boxes that require port-IO 152 delay for certain operations. Should work on most new machines. 153 154endchoice 155 156config DEBUG_BOOT_PARAMS 157 bool "Debug boot parameters" 158 depends on DEBUG_KERNEL 159 depends on DEBUG_FS 160 help 161 This option will cause struct boot_params to be exported via debugfs. 162 163config CPA_DEBUG 164 bool "CPA self-test code" 165 depends on DEBUG_KERNEL 166 help 167 Do change_page_attr() self-tests every 30 seconds. 168 169config DEBUG_ENTRY 170 bool "Debug low-level entry code" 171 depends on DEBUG_KERNEL 172 help 173 This option enables sanity checks in x86's low-level entry code. 174 Some of these sanity checks may slow down kernel entries and 175 exits or otherwise impact performance. 176 177 If unsure, say N. 178 179config DEBUG_NMI_SELFTEST 180 bool "NMI Selftest" 181 depends on DEBUG_KERNEL && X86_LOCAL_APIC 182 help 183 Enabling this option turns on a quick NMI selftest to verify 184 that the NMI behaves correctly. 185 186 This might help diagnose strange hangs that rely on NMI to 187 function properly. 188 189 If unsure, say N. 190 191config DEBUG_IMR_SELFTEST 192 bool "Isolated Memory Region self test" 193 depends on INTEL_IMR 194 help 195 This option enables automated sanity testing of the IMR code. 196 Some simple tests are run to verify IMR bounds checking, alignment 197 and overlapping. This option is really only useful if you are 198 debugging an IMR memory map or are modifying the IMR code and want to 199 test your changes. 200 201 If unsure say N here. 202 203config X86_DEBUG_FPU 204 bool "Debug the x86 FPU code" 205 depends on DEBUG_KERNEL 206 default y 207 help 208 If this option is enabled then there will be extra sanity 209 checks and (boot time) debug printouts added to the kernel. 210 This debugging adds some small amount of runtime overhead 211 to the kernel. 212 213 If unsure, say N. 214 215config PUNIT_ATOM_DEBUG 216 tristate "ATOM Punit debug driver" 217 depends on PCI 218 select DEBUG_FS 219 select IOSF_MBI 220 help 221 This is a debug driver, which gets the power states 222 of all Punit North Complex devices. The power states of 223 each device is exposed as part of the debugfs interface. 224 The current power state can be read from 225 /sys/kernel/debug/punit_atom/dev_power_state 226 227choice 228 prompt "Choose kernel unwinder" 229 default UNWINDER_ORC if X86_64 230 default UNWINDER_FRAME_POINTER if X86_32 231 help 232 This determines which method will be used for unwinding kernel stack 233 traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack, 234 livepatch, lockdep, and more. 235 236config UNWINDER_ORC 237 bool "ORC unwinder" 238 depends on X86_64 239 select OBJTOOL 240 help 241 This option enables the ORC (Oops Rewind Capability) unwinder for 242 unwinding kernel stack traces. It uses a custom data format which is 243 a simplified version of the DWARF Call Frame Information standard. 244 245 This unwinder is more accurate across interrupt entry frames than the 246 frame pointer unwinder. It also enables a 5-10% performance 247 improvement across the entire kernel compared to frame pointers. 248 249 Enabling this option will increase the kernel's runtime memory usage 250 by roughly 2-4MB, depending on your kernel config. 251 252config UNWINDER_FRAME_POINTER 253 bool "Frame pointer unwinder" 254 select FRAME_POINTER 255 help 256 This option enables the frame pointer unwinder for unwinding kernel 257 stack traces. 258 259 The unwinder itself is fast and it uses less RAM than the ORC 260 unwinder, but the kernel text size will grow by ~3% and the kernel's 261 overall performance will degrade by roughly 5-10%. 262 263config UNWINDER_GUESS 264 bool "Guess unwinder" 265 depends on EXPERT 266 depends on !STACKDEPOT 267 help 268 This option enables the "guess" unwinder for unwinding kernel stack 269 traces. It scans the stack and reports every kernel text address it 270 finds. Some of the addresses it reports may be incorrect. 271 272 While this option often produces false positives, it can still be 273 useful in many cases. Unlike the other unwinders, it has no runtime 274 overhead. 275 276endchoice 277 278config FRAME_POINTER 279 depends on !UNWINDER_ORC && !UNWINDER_GUESS 280 bool 281