arch/x86/Kconfig.debug

   1 # SPDX-License-Identifier: GPL-2.0
   2
   3 config TRACE_IRQFLAGS_SUPPORT
   4         def_bool y
   5
   6 config TRACE_IRQFLAGS_NMI_SUPPORT
   7         def_bool y
   8
   9 config EARLY_PRINTK_USB
  10         bool
  11
  12 config X86_VERBOSE_BOOTUP
  13         bool "Enable verbose x86 bootup info messages"
  14         default y
  15         help
  16           Enables the informational output from the decompression stage
  17           (e.g. bzImage) of the boot. If you disable this you will still
  18           see errors. Disable this if you want silent bootup.
  19
  20 config EARLY_PRINTK
  21         bool "Early printk" if EXPERT
  22         default y
  23         help
  24           Write kernel log output directly into the VGA buffer or to a serial
  25           port.
  26
  27           This is useful for kernel debugging when your machine crashes very
  28           early before the console code is initialized. For normal operation
  29           it is not recommended because it looks ugly and doesn't cooperate
  30           with klogd/syslogd or the X server. You should normally say N here,
  31           unless you want to debug such a crash.
  32
  33 config EARLY_PRINTK_DBGP
  34         bool "Early printk via EHCI debug port"
  35         depends on EARLY_PRINTK && PCI
  36         select EARLY_PRINTK_USB
  37         help
  38           Write kernel log output directly into the EHCI debug port.
  39
  40           This is useful for kernel debugging when your machine crashes very
  41           early before the console code is initialized. For normal operation
  42           it is not recommended because it looks ugly and doesn't cooperate
  43           with klogd/syslogd or the X server. You should normally say N here,
  44           unless you want to debug such a crash. You need usb debug device.
  45
  46 config EARLY_PRINTK_USB_XDBC
  47         bool "Early printk via the xHCI debug port"
  48         depends on EARLY_PRINTK && PCI
  49         select EARLY_PRINTK_USB
  50         help
  51           Write kernel log output directly into the xHCI debug port.
  52
  53           One use for this feature is kernel debugging, for example when your
  54           machine crashes very early before the regular console code is
  55           initialized. Other uses include simpler, lockless logging instead of
  56           a full-blown printk console driver + klogd.
  57
  58           For normal production environments this is normally not recommended,
  59           because it doesn't feed events into klogd/syslogd and doesn't try to
  60           print anything on the screen.
  61
  62           You should normally say N here, unless you want to debug early
  63           crashes or need a very simple printk logging facility.
  64
  65 config 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
  75 config 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
  94 config 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
 110 config 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
 117 config HAVE_MMIOTRACE_SUPPORT
 118         def_bool y
 119
 120 config 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
 130 choice
 131         prompt "IO delay type"
 132         default IO_DELAY_0X80
 133
 134 config 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
 140 config 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
 146 config 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
 152 config 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
 158 endchoice
 159
 160 config 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
 167 config 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
 173 config 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
 183 config 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
 195 config 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
 207 config 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
 219 config 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
 231 choice
 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
 240 config 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
 256 config 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
 267 config 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
 280 endchoice
 281
 282 config FRAME_POINTER
 283         depends on !UNWINDER_ORC && !UNWINDER_GUESS
 284         bool