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 STRICT_DEVMEM
   9         bool "Filter access to /dev/mem"
  10         ---help---
  11           If this option is disabled, you allow userspace (root) access to all
  12           of memory, including kernel and userspace memory. Accidental
  13           access to this is obviously disastrous, but specific access can
  14           be used by people debugging the kernel. Note that with PAT support
  15           enabled, even in this case there are restrictions on /dev/mem
  16           use due to the cache aliasing requirements.
  17
  18           If this option is switched on, the /dev/mem file only allows
  19           userspace access to PCI space and the BIOS code and data regions.
  20           This is sufficient for dosemu and X and all common users of
  21           /dev/mem.
  22
  23           If in doubt, say Y.
  24
  25 config X86_VERBOSE_BOOTUP
  26         bool "Enable verbose x86 bootup info messages"
  27         default y
  28         ---help---
  29           Enables the informational output from the decompression stage
  30           (e.g. bzImage) of the boot. If you disable this you will still
  31           see errors. Disable this if you want silent bootup.
  32
  33 config EARLY_PRINTK
  34         bool "Early printk" if EXPERT
  35         default y
  36         ---help---
  37           Write kernel log output directly into the VGA buffer or to a serial
  38           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 N here,
  44           unless you want to debug such a crash.
  45
  46 config EARLY_PRINTK_DBGP
  47         bool "Early printk via EHCI debug port"
  48         depends on EARLY_PRINTK && PCI
  49         ---help---
  50           Write kernel log output directly into the EHCI debug port.
  51
  52           This is useful for kernel debugging when your machine crashes very
  53           early before the console code is initialized. For normal operation
  54           it is not recommended because it looks ugly and doesn't cooperate
  55           with klogd/syslogd or the X server. You should normally N here,
  56           unless you want to debug such a crash. You need usb debug device.
  57
  58 config EARLY_PRINTK_EFI
  59         bool "Early printk via the EFI framebuffer"
  60         depends on EFI && EARLY_PRINTK
  61         select FONT_SUPPORT
  62         ---help---
  63           Write kernel log output directly into the EFI framebuffer.
  64
  65           This is useful for kernel debugging when your machine crashes very
  66           early before the console code is initialized.
  67
  68 config X86_PTDUMP
  69         bool "Export kernel pagetable layout to userspace via debugfs"
  70         depends on DEBUG_KERNEL
  71         select DEBUG_FS
  72         ---help---
  73           Say Y here if you want to show the kernel pagetable layout in a
  74           debugfs file. This information is only useful for kernel developers
  75           who are working in architecture specific areas of the kernel.
  76           It is probably not a good idea to enable this feature in a production
  77           kernel.
  78           If in doubt, say "N"
  79
  80 config EFI_PGT_DUMP
  81         bool "Dump the EFI pagetable"
  82         depends on EFI && X86_PTDUMP
  83         ---help---
  84           Enable this if you want to dump the EFI page table before
  85           enabling virtual mode. This can be used to debug miscellaneous
  86           issues with the mapping of the EFI runtime regions into that
  87           table.
  88
  89 config DEBUG_RODATA
  90         bool "Write protect kernel read-only data structures"
  91         default y
  92         depends on DEBUG_KERNEL
  93         ---help---
  94           Mark the kernel read-only data as write-protected in the pagetables,
  95           in order to catch accidental (and incorrect) writes to such const
  96           data. This is recommended so that we can catch kernel bugs sooner.
  97           If in doubt, say "Y".
  98
  99 config DEBUG_RODATA_TEST
 100         bool "Testcase for the DEBUG_RODATA feature"
 101         depends on DEBUG_RODATA
 102         default y
 103         ---help---
 104           This option enables a testcase for the DEBUG_RODATA
 105           feature as well as for the change_page_attr() infrastructure.
 106           If in doubt, say "N"
 107
 108 config DEBUG_SET_MODULE_RONX
 109         bool "Set loadable kernel module data as NX and text as RO"
 110         depends on MODULES
 111         ---help---
 112           This option helps catch unintended modifications to loadable
 113           kernel module's text and read-only data. It also prevents execution
 114           of module data. Such protection may interfere with run-time code
 115           patching and dynamic kernel tracing - and they might also protect
 116           against certain classes of kernel exploits.
 117           If in doubt, say "N".
 118
 119 config DEBUG_NX_TEST
 120         tristate "Testcase for the NX non-executable stack feature"
 121         depends on DEBUG_KERNEL && m
 122         ---help---
 123           This option enables a testcase for the CPU NX capability
 124           and the software setup of this feature.
 125           If in doubt, say "N"
 126
 127 config DOUBLEFAULT
 128         default y
 129         bool "Enable doublefault exception handler" if EXPERT
 130         ---help---
 131           This option allows trapping of rare doublefault exceptions that
 132           would otherwise cause a system to silently reboot. Disabling this
 133           option saves about 4k and might cause you much additional grey
 134           hair.
 135
 136 config DEBUG_TLBFLUSH
 137         bool "Set upper limit of TLB entries to flush one-by-one"
 138         depends on DEBUG_KERNEL
 139         ---help---
 140
 141         X86-only for now.
 142
 143         This option allows the user to tune the amount of TLB entries the
 144         kernel flushes one-by-one instead of doing a full TLB flush. In
 145         certain situations, the former is cheaper. This is controlled by the
 146         tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
 147         to -1, the code flushes the whole TLB unconditionally. Otherwise,
 148         for positive values of it, the kernel will use single TLB entry
 149         invalidating instructions according to the following formula:
 150
 151         flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
 152
 153         If in doubt, say "N".
 154
 155 config IOMMU_DEBUG
 156         bool "Enable IOMMU debugging"
 157         depends on GART_IOMMU && DEBUG_KERNEL
 158         depends on X86_64
 159         ---help---
 160           Force the IOMMU to on even when you have less than 4GB of
 161           memory and add debugging code. On overflow always panic. And
 162           allow to enable IOMMU leak tracing. Can be disabled at boot
 163           time with iommu=noforce. This will also enable scatter gather
 164           list merging.  Currently not recommended for production
 165           code. When you use it make sure you have a big enough
 166           IOMMU/AGP aperture.  Most of the options enabled by this can
 167           be set more finegrained using the iommu= command line
 168           options. See Documentation/x86/x86_64/boot-options.txt for more
 169           details.
 170
 171 config IOMMU_STRESS
 172         bool "Enable IOMMU stress-test mode"
 173         ---help---
 174           This option disables various optimizations in IOMMU related
 175           code to do real stress testing of the IOMMU code. This option
 176           will cause a performance drop and should only be enabled for
 177           testing.
 178
 179 config IOMMU_LEAK
 180         bool "IOMMU leak tracing"
 181         depends on IOMMU_DEBUG && DMA_API_DEBUG
 182         ---help---
 183           Add a simple leak tracer to the IOMMU code. This is useful when you
 184           are debugging a buggy device driver that leaks IOMMU mappings.
 185
 186 config HAVE_MMIOTRACE_SUPPORT
 187         def_bool y
 188
 189 config X86_DECODER_SELFTEST
 190         bool "x86 instruction decoder selftest"
 191         depends on DEBUG_KERNEL && KPROBES
 192         depends on !COMPILE_TEST
 193         ---help---
 194          Perform x86 instruction decoder selftests at build time.
 195          This option is useful for checking the sanity of x86 instruction
 196          decoder code.
 197          If unsure, say "N".
 198
 199 #
 200 # IO delay types:
 201 #
 202
 203 config IO_DELAY_TYPE_0X80
 204         int
 205         default "0"
 206
 207 config IO_DELAY_TYPE_0XED
 208         int
 209         default "1"
 210
 211 config IO_DELAY_TYPE_UDELAY
 212         int
 213         default "2"
 214
 215 config IO_DELAY_TYPE_NONE
 216         int
 217         default "3"
 218
 219 choice
 220         prompt "IO delay type"
 221         default IO_DELAY_0X80
 222
 223 config IO_DELAY_0X80
 224         bool "port 0x80 based port-IO delay [recommended]"
 225         ---help---
 226           This is the traditional Linux IO delay used for in/out_p.
 227           It is the most tested hence safest selection here.
 228
 229 config IO_DELAY_0XED
 230         bool "port 0xed based port-IO delay"
 231         ---help---
 232           Use port 0xed as the IO delay. This frees up port 0x80 which is
 233           often used as a hardware-debug port.
 234
 235 config IO_DELAY_UDELAY
 236         bool "udelay based port-IO delay"
 237         ---help---
 238           Use udelay(2) as the IO delay method. This provides the delay
 239           while not having any side-effect on the IO port space.
 240
 241 config IO_DELAY_NONE
 242         bool "no port-IO delay"
 243         ---help---
 244           No port-IO delay. Will break on old boxes that require port-IO
 245           delay for certain operations. Should work on most new machines.
 246
 247 endchoice
 248
 249 if IO_DELAY_0X80
 250 config DEFAULT_IO_DELAY_TYPE
 251         int
 252         default IO_DELAY_TYPE_0X80
 253 endif
 254
 255 if IO_DELAY_0XED
 256 config DEFAULT_IO_DELAY_TYPE
 257         int
 258         default IO_DELAY_TYPE_0XED
 259 endif
 260
 261 if IO_DELAY_UDELAY
 262 config DEFAULT_IO_DELAY_TYPE
 263         int
 264         default IO_DELAY_TYPE_UDELAY
 265 endif
 266
 267 if IO_DELAY_NONE
 268 config DEFAULT_IO_DELAY_TYPE
 269         int
 270         default IO_DELAY_TYPE_NONE
 271 endif
 272
 273 config DEBUG_BOOT_PARAMS
 274         bool "Debug boot parameters"
 275         depends on DEBUG_KERNEL
 276         depends on DEBUG_FS
 277         ---help---
 278           This option will cause struct boot_params to be exported via debugfs.
 279
 280 config CPA_DEBUG
 281         bool "CPA self-test code"
 282         depends on DEBUG_KERNEL
 283         ---help---
 284           Do change_page_attr() self-tests every 30 seconds.
 285
 286 config OPTIMIZE_INLINING
 287         bool "Allow gcc to uninline functions marked 'inline'"
 288         ---help---
 289           This option determines if the kernel forces gcc to inline the functions
 290           developers have marked 'inline'. Doing so takes away freedom from gcc to
 291           do what it thinks is best, which is desirable for the gcc 3.x series of
 292           compilers. The gcc 4.x series have a rewritten inlining algorithm and
 293           enabling this option will generate a smaller kernel there. Hopefully
 294           this algorithm is so good that allowing gcc 4.x and above to make the
 295           decision will become the default in the future. Until then this option
 296           is there to test gcc for this.
 297
 298           If unsure, say N.
 299
 300 config DEBUG_NMI_SELFTEST
 301         bool "NMI Selftest"
 302         depends on DEBUG_KERNEL && X86_LOCAL_APIC
 303         ---help---
 304           Enabling this option turns on a quick NMI selftest to verify
 305           that the NMI behaves correctly.
 306
 307           This might help diagnose strange hangs that rely on NMI to
 308           function properly.
 309
 310           If unsure, say N.
 311
 312 config DEBUG_IMR_SELFTEST
 313         bool "Isolated Memory Region self test"
 314         default n
 315         depends on INTEL_IMR
 316         ---help---
 317           This option enables automated sanity testing of the IMR code.
 318           Some simple tests are run to verify IMR bounds checking, alignment
 319           and overlapping. This option is really only useful if you are
 320           debugging an IMR memory map or are modifying the IMR code and want to
 321           test your changes.
 322
 323           If unsure say N here.
 324
 325 config X86_DEBUG_STATIC_CPU_HAS
 326         bool "Debug alternatives"
 327         depends on DEBUG_KERNEL
 328         ---help---
 329           This option causes additional code to be generated which
 330           fails if static_cpu_has() is used before alternatives have
 331           run.
 332
 333           If unsure, say N.
 334
 335 endmenu