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