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