arch/x86/Kconfig.debug

   1 menu "Kernel hacking"
   2
   3 config TRACE_IRQFLAGS_SUPPORT
   4         def_bool y
   5
   6 source "lib/Kconfig.debug"
   7
   8 config X86_VERBOSE_BOOTUP
   9         bool "Enable verbose x86 bootup info messages"
  10         default y
  11         ---help---
  12           Enables the informational output from the decompression stage
  13           (e.g. bzImage) of the boot. If you disable this you will still
  14           see errors. Disable this if you want silent bootup.
  15
  16 config EARLY_PRINTK
  17         bool "Early printk" if EXPERT
  18         default y
  19         ---help---
  20           Write kernel log output directly into the VGA buffer or to a serial
  21           port.
  22
  23           This is useful for kernel debugging when your machine crashes very
  24           early before the console code is initialized. For normal operation
  25           it is not recommended because it looks ugly and doesn't cooperate
  26           with klogd/syslogd or the X server. You should normally N here,
  27           unless you want to debug such a crash.
  28
  29 config EARLY_PRINTK_DBGP
  30         bool "Early printk via EHCI debug port"
  31         depends on EARLY_PRINTK && PCI
  32         ---help---
  33           Write kernel log output directly into the EHCI debug port.
  34
  35           This is useful for kernel debugging when your machine crashes very
  36           early before the console code is initialized. For normal operation
  37           it is not recommended because it looks ugly and doesn't cooperate
  38           with klogd/syslogd or the X server. You should normally N here,
  39           unless you want to debug such a crash. You need usb debug device.
  40
  41 config EARLY_PRINTK_EFI
  42         bool "Early printk via the EFI framebuffer"
  43         depends on EFI && EARLY_PRINTK
  44         select FONT_SUPPORT
  45         ---help---
  46           Write kernel log output directly into the EFI framebuffer.
  47
  48           This is useful for kernel debugging when your machine crashes very
  49           early before the console code is initialized.
  50
  51 config X86_PTDUMP_CORE
  52         def_bool n
  53
  54 config X86_PTDUMP
  55         tristate "Export kernel pagetable layout to userspace via debugfs"
  56         depends on DEBUG_KERNEL
  57         select DEBUG_FS
  58         select X86_PTDUMP_CORE
  59         ---help---
  60           Say Y here if you want to show the kernel pagetable layout in a
  61           debugfs file. This information is only useful for kernel developers
  62           who are working in architecture specific areas of the kernel.
  63           It is probably not a good idea to enable this feature in a production
  64           kernel.
  65           If in doubt, say "N"
  66
  67 config EFI_PGT_DUMP
  68         bool "Dump the EFI pagetable"
  69         depends on EFI
  70         select X86_PTDUMP_CORE
  71         ---help---
  72           Enable this if you want to dump the EFI page table before
  73           enabling virtual mode. This can be used to debug miscellaneous
  74           issues with the mapping of the EFI runtime regions into that
  75           table.
  76
  77 config DEBUG_RODATA_TEST
  78         bool "Testcase for the marking rodata read-only"
  79         default y
  80         ---help---
  81           This option enables a testcase for the setting rodata read-only
  82           as well as for the change_page_attr() infrastructure.
  83           If in doubt, say "N"
  84
  85 config DEBUG_WX
  86         bool "Warn on W+X mappings at boot"
  87         select X86_PTDUMP_CORE
  88         ---help---
  89           Generate a warning if any W+X mappings are found at boot.
  90
  91           This is useful for discovering cases where the kernel is leaving
  92           W+X mappings after applying NX, as such mappings are a security risk.
  93
  94           Look for a message in dmesg output like this:
  95
  96             x86/mm: Checked W+X mappings: passed, no W+X pages found.
  97
  98           or like this, if the check failed:
  99
 100             x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found.
 101
 102           Note that even if the check fails, your kernel is possibly
 103           still fine, as W+X mappings are not a security hole in
 104           themselves, what they do is that they make the exploitation
 105           of other unfixed kernel bugs easier.
 106
 107           There is no runtime or memory usage effect of this option
 108           once the kernel has booted up - it's a one time check.
 109
 110           If in doubt, say "Y".
 111
 112 config DOUBLEFAULT
 113         default y
 114         bool "Enable doublefault exception handler" if EXPERT
 115         ---help---
 116           This option allows trapping of rare doublefault exceptions that
 117           would otherwise cause a system to silently reboot. Disabling this
 118           option saves about 4k and might cause you much additional grey
 119           hair.
 120
 121 config DEBUG_TLBFLUSH
 122         bool "Set upper limit of TLB entries to flush one-by-one"
 123         depends on DEBUG_KERNEL
 124         ---help---
 125
 126         X86-only for now.
 127
 128         This option allows the user to tune the amount of TLB entries the
 129         kernel flushes one-by-one instead of doing a full TLB flush. In
 130         certain situations, the former is cheaper. This is controlled by the
 131         tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
 132         to -1, the code flushes the whole TLB unconditionally. Otherwise,
 133         for positive values of it, the kernel will use single TLB entry
 134         invalidating instructions according to the following formula:
 135
 136         flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
 137
 138         If in doubt, say "N".
 139
 140 config IOMMU_DEBUG
 141         bool "Enable IOMMU debugging"
 142         depends on GART_IOMMU && DEBUG_KERNEL
 143         depends on X86_64
 144         ---help---
 145           Force the IOMMU to on even when you have less than 4GB of
 146           memory and add debugging code. On overflow always panic. And
 147           allow to enable IOMMU leak tracing. Can be disabled at boot
 148           time with iommu=noforce. This will also enable scatter gather
 149           list merging.  Currently not recommended for production
 150           code. When you use it make sure you have a big enough
 151           IOMMU/AGP aperture.  Most of the options enabled by this can
 152           be set more finegrained using the iommu= command line
 153           options. See Documentation/x86/x86_64/boot-options.txt for more
 154           details.
 155
 156 config IOMMU_STRESS
 157         bool "Enable IOMMU stress-test mode"
 158         ---help---
 159           This option disables various optimizations in IOMMU related
 160           code to do real stress testing of the IOMMU code. This option
 161           will cause a performance drop and should only be enabled for
 162           testing.
 163
 164 config IOMMU_LEAK
 165         bool "IOMMU leak tracing"
 166         depends on IOMMU_DEBUG && DMA_API_DEBUG
 167         ---help---
 168           Add a simple leak tracer to the IOMMU code. This is useful when you
 169           are debugging a buggy device driver that leaks IOMMU mappings.
 170
 171 config HAVE_MMIOTRACE_SUPPORT
 172         def_bool y
 173
 174 config X86_DECODER_SELFTEST
 175         bool "x86 instruction decoder selftest"
 176         depends on DEBUG_KERNEL && KPROBES
 177         depends on !COMPILE_TEST
 178         ---help---
 179          Perform x86 instruction decoder selftests at build time.
 180          This option is useful for checking the sanity of x86 instruction
 181          decoder code.
 182          If unsure, say "N".
 183
 184 #
 185 # IO delay types:
 186 #
 187
 188 config IO_DELAY_TYPE_0X80
 189         int
 190         default "0"
 191
 192 config IO_DELAY_TYPE_0XED
 193         int
 194         default "1"
 195
 196 config IO_DELAY_TYPE_UDELAY
 197         int
 198         default "2"
 199
 200 config IO_DELAY_TYPE_NONE
 201         int
 202         default "3"
 203
 204 choice
 205         prompt "IO delay type"
 206         default IO_DELAY_0X80
 207
 208 config IO_DELAY_0X80
 209         bool "port 0x80 based port-IO delay [recommended]"
 210         ---help---
 211           This is the traditional Linux IO delay used for in/out_p.
 212           It is the most tested hence safest selection here.
 213
 214 config IO_DELAY_0XED
 215         bool "port 0xed based port-IO delay"
 216         ---help---
 217           Use port 0xed as the IO delay. This frees up port 0x80 which is
 218           often used as a hardware-debug port.
 219
 220 config IO_DELAY_UDELAY
 221         bool "udelay based port-IO delay"
 222         ---help---
 223           Use udelay(2) as the IO delay method. This provides the delay
 224           while not having any side-effect on the IO port space.
 225
 226 config IO_DELAY_NONE
 227         bool "no port-IO delay"
 228         ---help---
 229           No port-IO delay. Will break on old boxes that require port-IO
 230           delay for certain operations. Should work on most new machines.
 231
 232 endchoice
 233
 234 if IO_DELAY_0X80
 235 config DEFAULT_IO_DELAY_TYPE
 236         int
 237         default IO_DELAY_TYPE_0X80
 238 endif
 239
 240 if IO_DELAY_0XED
 241 config DEFAULT_IO_DELAY_TYPE
 242         int
 243         default IO_DELAY_TYPE_0XED
 244 endif
 245
 246 if IO_DELAY_UDELAY
 247 config DEFAULT_IO_DELAY_TYPE
 248         int
 249         default IO_DELAY_TYPE_UDELAY
 250 endif
 251
 252 if IO_DELAY_NONE
 253 config DEFAULT_IO_DELAY_TYPE
 254         int
 255         default IO_DELAY_TYPE_NONE
 256 endif
 257
 258 config DEBUG_BOOT_PARAMS
 259         bool "Debug boot parameters"
 260         depends on DEBUG_KERNEL
 261         depends on DEBUG_FS
 262         ---help---
 263           This option will cause struct boot_params to be exported via debugfs.
 264
 265 config CPA_DEBUG
 266         bool "CPA self-test code"
 267         depends on DEBUG_KERNEL
 268         ---help---
 269           Do change_page_attr() self-tests every 30 seconds.
 270
 271 config OPTIMIZE_INLINING
 272         bool "Allow gcc to uninline functions marked 'inline'"
 273         ---help---
 274           This option determines if the kernel forces gcc to inline the functions
 275           developers have marked 'inline'. Doing so takes away freedom from gcc to
 276           do what it thinks is best, which is desirable for the gcc 3.x series of
 277           compilers. The gcc 4.x series have a rewritten inlining algorithm and
 278           enabling this option will generate a smaller kernel there. Hopefully
 279           this algorithm is so good that allowing gcc 4.x and above to make the
 280           decision will become the default in the future. Until then this option
 281           is there to test gcc for this.
 282
 283           If unsure, say N.
 284
 285 config DEBUG_ENTRY
 286         bool "Debug low-level entry code"
 287         depends on DEBUG_KERNEL
 288         ---help---
 289           This option enables sanity checks in x86's low-level entry code.
 290           Some of these sanity checks may slow down kernel entries and
 291           exits or otherwise impact performance.
 292
 293           This is currently used to help test NMI code.
 294
 295           If unsure, say N.
 296
 297 config DEBUG_NMI_SELFTEST
 298         bool "NMI Selftest"
 299         depends on DEBUG_KERNEL && X86_LOCAL_APIC
 300         ---help---
 301           Enabling this option turns on a quick NMI selftest to verify
 302           that the NMI behaves correctly.
 303
 304           This might help diagnose strange hangs that rely on NMI to
 305           function properly.
 306
 307           If unsure, say N.
 308
 309 config DEBUG_IMR_SELFTEST
 310         bool "Isolated Memory Region self test"
 311         default n
 312         depends on INTEL_IMR
 313         ---help---
 314           This option enables automated sanity testing of the IMR code.
 315           Some simple tests are run to verify IMR bounds checking, alignment
 316           and overlapping. This option is really only useful if you are
 317           debugging an IMR memory map or are modifying the IMR code and want to
 318           test your changes.
 319
 320           If unsure say N here.
 321
 322 config X86_DEBUG_FPU
 323         bool "Debug the x86 FPU code"
 324         depends on DEBUG_KERNEL
 325         default y
 326         ---help---
 327           If this option is enabled then there will be extra sanity
 328           checks and (boot time) debug printouts added to the kernel.
 329           This debugging adds some small amount of runtime overhead
 330           to the kernel.
 331
 332           If unsure, say N.
 333
 334 config PUNIT_ATOM_DEBUG
 335         tristate "ATOM Punit debug driver"
 336         select DEBUG_FS
 337         select IOSF_MBI
 338         ---help---
 339           This is a debug driver, which gets the power states
 340           of all Punit North Complex devices. The power states of
 341           each device is exposed as part of the debugfs interface.
 342           The current power state can be read from
 343           /sys/kernel/debug/punit_atom/dev_power_state
 344
 345 endmenu