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 comment "Page alloc debug is incompatible with Software Suspend on i386"
  38         depends on DEBUG_KERNEL && HIBERNATION
  39         depends on X86_32
  40
  41 config DEBUG_PAGEALLOC
  42         bool "Debug page memory allocations"
  43         depends on DEBUG_KERNEL && !HIBERNATION && !HUGETLBFS
  44         depends on X86_32
  45         help
  46           Unmap pages from the kernel linear mapping after free_pages().
  47           This results in a large slowdown, but helps to find certain types
  48           of memory corruptions.
  49
  50 config DEBUG_PER_CPU_MAPS
  51         bool "Debug access to per_cpu maps"
  52         depends on DEBUG_KERNEL
  53         depends on X86_64_SMP
  54         default n
  55         help
  56           Say Y to verify that the per_cpu map being accessed has
  57           been setup.  Adds a fair amount of code to kernel memory
  58           and decreases performance.
  59
  60           Say N if unsure.
  61
  62 config DEBUG_RODATA
  63         bool "Write protect kernel read-only data structures"
  64         default y
  65         depends on DEBUG_KERNEL
  66         help
  67           Mark the kernel read-only data as write-protected in the pagetables,
  68           in order to catch accidental (and incorrect) writes to such const
  69           data. This is recommended so that we can catch kernel bugs sooner.
  70           If in doubt, say "Y".
  71
  72 config 4KSTACKS
  73         bool "Use 4Kb for kernel stacks instead of 8Kb"
  74         depends on DEBUG_KERNEL
  75         depends on X86_32
  76         help
  77           If you say Y here the kernel will use a 4Kb stacksize for the
  78           kernel stack attached to each process/thread. This facilitates
  79           running more threads on a system and also reduces the pressure
  80           on the VM subsystem for higher order allocations. This option
  81           will also use IRQ stacks to compensate for the reduced stackspace.
  82
  83 config X86_FIND_SMP_CONFIG
  84         def_bool y
  85         depends on X86_LOCAL_APIC || X86_VOYAGER
  86         depends on X86_32
  87
  88 config X86_MPPARSE
  89         def_bool y
  90         depends on (X86_32 && (X86_LOCAL_APIC && !X86_VISWS)) || X86_64
  91
  92 config DOUBLEFAULT
  93         default y
  94         bool "Enable doublefault exception handler" if EMBEDDED
  95         depends on X86_32
  96         help
  97           This option allows trapping of rare doublefault exceptions that
  98           would otherwise cause a system to silently reboot. Disabling this
  99           option saves about 4k and might cause you much additional grey
 100           hair.
 101
 102 config IOMMU_DEBUG
 103         bool "Enable IOMMU debugging"
 104         depends on GART_IOMMU && DEBUG_KERNEL
 105         depends on X86_64
 106         help
 107           Force the IOMMU to on even when you have less than 4GB of
 108           memory and add debugging code. On overflow always panic. And
 109           allow to enable IOMMU leak tracing. Can be disabled at boot
 110           time with iommu=noforce. This will also enable scatter gather
 111           list merging.  Currently not recommended for production
 112           code. When you use it make sure you have a big enough
 113           IOMMU/AGP aperture.  Most of the options enabled by this can
 114           be set more finegrained using the iommu= command line
 115           options. See Documentation/x86_64/boot-options.txt for more
 116           details.
 117
 118 config IOMMU_LEAK
 119         bool "IOMMU leak tracing"
 120         depends on DEBUG_KERNEL
 121         depends on IOMMU_DEBUG
 122         help
 123           Add a simple leak tracer to the IOMMU code. This is useful when you
 124           are debugging a buggy device driver that leaks IOMMU mappings.
 125
 126 #
 127 # IO delay types:
 128 #
 129
 130 config IO_DELAY_TYPE_0X80
 131         int
 132         default "0"
 133
 134 config IO_DELAY_TYPE_0XED
 135         int
 136         default "1"
 137
 138 config IO_DELAY_TYPE_UDELAY
 139         int
 140         default "2"
 141
 142 config IO_DELAY_TYPE_NONE
 143         int
 144         default "3"
 145
 146 choice
 147         prompt "IO delay type"
 148         default IO_DELAY_0XED
 149
 150 config IO_DELAY_0X80
 151         bool "port 0x80 based port-IO delay [recommended]"
 152         help
 153           This is the traditional Linux IO delay used for in/out_p.
 154           It is the most tested hence safest selection here.
 155
 156 config IO_DELAY_0XED
 157         bool "port 0xed based port-IO delay"
 158         help
 159           Use port 0xed as the IO delay. This frees up port 0x80 which is
 160           often used as a hardware-debug port.
 161
 162 config IO_DELAY_UDELAY
 163         bool "udelay based port-IO delay"
 164         help
 165           Use udelay(2) as the IO delay method. This provides the delay
 166           while not having any side-effect on the IO port space.
 167
 168 config IO_DELAY_NONE
 169         bool "no port-IO delay"
 170         help
 171           No port-IO delay. Will break on old boxes that require port-IO
 172           delay for certain operations. Should work on most new machines.
 173
 174 endchoice
 175
 176 if IO_DELAY_0X80
 177 config DEFAULT_IO_DELAY_TYPE
 178         int
 179         default IO_DELAY_TYPE_0X80
 180 endif
 181
 182 if IO_DELAY_0XED
 183 config DEFAULT_IO_DELAY_TYPE
 184         int
 185         default IO_DELAY_TYPE_0XED
 186 endif
 187
 188 if IO_DELAY_UDELAY
 189 config DEFAULT_IO_DELAY_TYPE
 190         int
 191         default IO_DELAY_TYPE_UDELAY
 192 endif
 193
 194 if IO_DELAY_NONE
 195 config DEFAULT_IO_DELAY_TYPE
 196         int
 197         default IO_DELAY_TYPE_NONE
 198 endif
 199
 200 config DEBUG_BOOT_PARAMS
 201         bool "Debug boot parameters"
 202         depends on DEBUG_KERNEL
 203         depends on DEBUG_FS
 204         help
 205           This option will cause struct boot_params to be exported via debugfs.
 206
 207 endmenu