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 EARLY_PRINTK
   9         bool "Early printk" if EMBEDDED
  10         default y
  11         help
  12           Write kernel log output directly into the VGA buffer or to a serial
  13           port.
  14
  15           This is useful for kernel debugging when your machine crashes very
  16           early before the console code is initialized. For normal operation
  17           it is not recommended because it looks ugly and doesn't cooperate
  18           with klogd/syslogd or the X server. You should normally N here,
  19           unless you want to debug such a crash.
  20
  21 config DEBUG_STACKOVERFLOW
  22         bool "Check for stack overflows"
  23         depends on DEBUG_KERNEL
  24         help
  25           This option will cause messages to be printed if free stack space
  26           drops below a certain limit.
  27
  28 config DEBUG_STACK_USAGE
  29         bool "Stack utilization instrumentation"
  30         depends on DEBUG_KERNEL
  31         help
  32           Enables the display of the minimum amount of free stack which each
  33           task has ever had available in the sysrq-T and sysrq-P debug output.
  34
  35           This option will slow down process creation somewhat.
  36
  37 config DEBUG_PAGEALLOC
  38         bool "Debug page memory allocations"
  39         depends on DEBUG_KERNEL
  40         help
  41           Unmap pages from the kernel linear mapping after free_pages().
  42           This results in a large slowdown, but helps to find certain types
  43           of memory corruptions.
  44
  45 config DEBUG_PER_CPU_MAPS
  46         bool "Debug access to per_cpu maps"
  47         depends on DEBUG_KERNEL
  48         depends on X86_64_SMP
  49         default n
  50         help
  51           Say Y to verify that the per_cpu map being accessed has
  52           been setup.  Adds a fair amount of code to kernel memory
  53           and decreases performance.
  54
  55           Say N if unsure.
  56
  57 config DEBUG_RODATA
  58         bool "Write protect kernel read-only data structures"
  59         default y
  60         depends on DEBUG_KERNEL
  61         help
  62           Mark the kernel read-only data as write-protected in the pagetables,
  63           in order to catch accidental (and incorrect) writes to such const
  64           data. This is recommended so that we can catch kernel bugs sooner.
  65           If in doubt, say "Y".
  66
  67 config DEBUG_RODATA_TEST
  68         bool "Testcase for the DEBUG_RODATA feature"
  69         depends on DEBUG_RODATA
  70         help
  71           This option enables a testcase for the DEBUG_RODATA
  72           feature as well as for the change_page_attr() infrastructure.
  73           If in doubt, say "N"
  74
  75 config DEBUG_NX_TEST
  76         tristate "Testcase for the NX non-executable stack feature"
  77         depends on DEBUG_KERNEL && m
  78         help
  79           This option enables a testcase for the CPU NX capability
  80           and the software setup of this feature.
  81           If in doubt, say "N"
  82
  83 config 4KSTACKS
  84         bool "Use 4Kb for kernel stacks instead of 8Kb"
  85         depends on DEBUG_KERNEL
  86         depends on X86_32
  87         help
  88           If you say Y here the kernel will use a 4Kb stacksize for the
  89           kernel stack attached to each process/thread. This facilitates
  90           running more threads on a system and also reduces the pressure
  91           on the VM subsystem for higher order allocations. This option
  92           will also use IRQ stacks to compensate for the reduced stackspace.
  93
  94 config X86_FIND_SMP_CONFIG
  95         def_bool y
  96         depends on X86_LOCAL_APIC || X86_VOYAGER
  97         depends on X86_32
  98
  99 config X86_MPPARSE
 100         def_bool y
 101         depends on (X86_32 && (X86_LOCAL_APIC && !X86_VISWS)) || X86_64
 102
 103 config DOUBLEFAULT
 104         default y
 105         bool "Enable doublefault exception handler" if EMBEDDED
 106         depends on X86_32
 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 IOMMU_DEBUG
 114         bool "Enable IOMMU debugging"
 115         depends on GART_IOMMU && DEBUG_KERNEL
 116         depends on X86_64
 117         help
 118           Force the IOMMU to on even when you have less than 4GB of
 119           memory and add debugging code. On overflow always panic. And
 120           allow to enable IOMMU leak tracing. Can be disabled at boot
 121           time with iommu=noforce. This will also enable scatter gather
 122           list merging.  Currently not recommended for production
 123           code. When you use it make sure you have a big enough
 124           IOMMU/AGP aperture.  Most of the options enabled by this can
 125           be set more finegrained using the iommu= command line
 126           options. See Documentation/x86_64/boot-options.txt for more
 127           details.
 128
 129 config IOMMU_LEAK
 130         bool "IOMMU leak tracing"
 131         depends on DEBUG_KERNEL
 132         depends on IOMMU_DEBUG
 133         help
 134           Add a simple leak tracer to the IOMMU code. This is useful when you
 135           are debugging a buggy device driver that leaks IOMMU mappings.
 136
 137 #
 138 # IO delay types:
 139 #
 140
 141 config IO_DELAY_TYPE_0X80
 142         int
 143         default "0"
 144
 145 config IO_DELAY_TYPE_0XED
 146         int
 147         default "1"
 148
 149 config IO_DELAY_TYPE_UDELAY
 150         int
 151         default "2"
 152
 153 config IO_DELAY_TYPE_NONE
 154         int
 155         default "3"
 156
 157 choice
 158         prompt "IO delay type"
 159         default IO_DELAY_0X80
 160
 161 config IO_DELAY_0X80
 162         bool "port 0x80 based port-IO delay [recommended]"
 163         help
 164           This is the traditional Linux IO delay used for in/out_p.
 165           It is the most tested hence safest selection here.
 166
 167 config IO_DELAY_0XED
 168         bool "port 0xed based port-IO delay"
 169         help
 170           Use port 0xed as the IO delay. This frees up port 0x80 which is
 171           often used as a hardware-debug port.
 172
 173 config IO_DELAY_UDELAY
 174         bool "udelay based port-IO delay"
 175         help
 176           Use udelay(2) as the IO delay method. This provides the delay
 177           while not having any side-effect on the IO port space.
 178
 179 config IO_DELAY_NONE
 180         bool "no port-IO delay"
 181         help
 182           No port-IO delay. Will break on old boxes that require port-IO
 183           delay for certain operations. Should work on most new machines.
 184
 185 endchoice
 186
 187 if IO_DELAY_0X80
 188 config DEFAULT_IO_DELAY_TYPE
 189         int
 190         default IO_DELAY_TYPE_0X80
 191 endif
 192
 193 if IO_DELAY_0XED
 194 config DEFAULT_IO_DELAY_TYPE
 195         int
 196         default IO_DELAY_TYPE_0XED
 197 endif
 198
 199 if IO_DELAY_UDELAY
 200 config DEFAULT_IO_DELAY_TYPE
 201         int
 202         default IO_DELAY_TYPE_UDELAY
 203 endif
 204
 205 if IO_DELAY_NONE
 206 config DEFAULT_IO_DELAY_TYPE
 207         int
 208         default IO_DELAY_TYPE_NONE
 209 endif
 210
 211 config DEBUG_BOOT_PARAMS
 212         bool "Debug boot parameters"
 213         depends on DEBUG_KERNEL
 214         depends on DEBUG_FS
 215         help
 216           This option will cause struct boot_params to be exported via debugfs.
 217
 218 config CPA_DEBUG
 219         bool "CPA self-test code"
 220         depends on DEBUG_KERNEL
 221         help
 222           Do change_page_attr() self-tests every 30 seconds.
 223
 224 endmenu