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 && DEBUG_KERNEL && X86_32
  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_LOCAL_APIC && !X86_VISWS
  79         depends on X86_32
  80
  81 config DOUBLEFAULT
  82         default y
  83         bool "Enable doublefault exception handler" if EMBEDDED
  84         depends on X86_32
  85         help
  86           This option allows trapping of rare doublefault exceptions that
  87           would otherwise cause a system to silently reboot. Disabling this
  88           option saves about 4k and might cause you much additional grey
  89           hair.
  90
  91 config IOMMU_DEBUG
  92         bool "Enable IOMMU debugging"
  93         depends on GART_IOMMU && DEBUG_KERNEL
  94         depends on X86_64
  95         help
  96           Force the IOMMU to on even when you have less than 4GB of
  97           memory and add debugging code. On overflow always panic. And
  98           allow to enable IOMMU leak tracing. Can be disabled at boot
  99           time with iommu=noforce. This will also enable scatter gather
 100           list merging.  Currently not recommended for production
 101           code. When you use it make sure you have a big enough
 102           IOMMU/AGP aperture.  Most of the options enabled by this can
 103           be set more finegrained using the iommu= command line
 104           options. See Documentation/x86_64/boot-options.txt for more
 105           details.
 106
 107 config IOMMU_LEAK
 108         bool "IOMMU leak tracing"
 109         depends on DEBUG_KERNEL
 110         depends on IOMMU_DEBUG
 111         help
 112           Add a simple leak tracer to the IOMMU code. This is useful when you
 113           are debugging a buggy device driver that leaks IOMMU mappings.
 114
 115 #
 116 # IO delay types:
 117 #
 118
 119 config IO_DELAY_TYPE_0X80
 120         int
 121         default "0"
 122
 123 config IO_DELAY_TYPE_0XED
 124         int
 125         default "1"
 126
 127 config IO_DELAY_TYPE_UDELAY
 128         int
 129         default "2"
 130
 131 config IO_DELAY_TYPE_NONE
 132         int
 133         default "3"
 134
 135 choice
 136         prompt "IO delay type"
 137         default IO_DELAY_0X80
 138
 139 config IO_DELAY_0X80
 140         bool "port 0x80 based port-IO delay [recommended]"
 141         help
 142           This is the traditional Linux IO delay used for in/out_p.
 143           It is the most tested hence safest selection here.
 144
 145 config IO_DELAY_0XED
 146         bool "port 0xed based port-IO delay"
 147         help
 148           Use port 0xed as the IO delay. This frees up port 0x80 which is
 149           often used as a hardware-debug port.
 150
 151 config IO_DELAY_UDELAY
 152         bool "udelay based port-IO delay"
 153         help
 154           Use udelay(2) as the IO delay method. This provides the delay
 155           while not having any side-effect on the IO port space.
 156
 157 config IO_DELAY_NONE
 158         bool "no port-IO delay"
 159         help
 160           No port-IO delay. Will break on old boxes that require port-IO
 161           delay for certain operations. Should work on most new machines.
 162
 163 endchoice
 164
 165 if IO_DELAY_0X80
 166 config DEFAULT_IO_DELAY_TYPE
 167         int
 168         default IO_DELAY_TYPE_0X80
 169 endif
 170
 171 if IO_DELAY_0XED
 172 config DEFAULT_IO_DELAY_TYPE
 173         int
 174         default IO_DELAY_TYPE_0XED
 175 endif
 176
 177 if IO_DELAY_UDELAY
 178 config DEFAULT_IO_DELAY_TYPE
 179         int
 180         default IO_DELAY_TYPE_UDELAY
 181 endif
 182
 183 if IO_DELAY_NONE
 184 config DEFAULT_IO_DELAY_TYPE
 185         int
 186         default IO_DELAY_TYPE_NONE
 187 endif
 188
 189 endmenu