[mirror_ubuntu-artful-kernel.git] / arch / x86 / Kconfig.debug

menu "Kernel hacking"

config TRACE_IRQFLAGS_SUPPORT
	def_bool y

source "lib/Kconfig.debug"

config EARLY_PRINTK
	bool "Early printk" if EMBEDDED && DEBUG_KERNEL && X86_32
	default y
	help
	  Write kernel log output directly into the VGA buffer or to a serial
	  port.

	  This is useful for kernel debugging when your machine crashes very
	  early before the console code is initialized. For normal operation
	  it is not recommended because it looks ugly and doesn't cooperate
	  with klogd/syslogd or the X server. You should normally N here,
	  unless you want to debug such a crash.

config DEBUG_STACKOVERFLOW
	bool "Check for stack overflows"
	depends on DEBUG_KERNEL
	help
	  This option will cause messages to be printed if free stack space
	  drops below a certain limit.

config DEBUG_STACK_USAGE
	bool "Stack utilization instrumentation"
	depends on DEBUG_KERNEL
	help
	  Enables the display of the minimum amount of free stack which each
	  task has ever had available in the sysrq-T and sysrq-P debug output.

	  This option will slow down process creation somewhat.

comment "Page alloc debug is incompatible with Software Suspend on i386"
	depends on DEBUG_KERNEL && HIBERNATION
	depends on X86_32

config DEBUG_PAGEALLOC
	bool "Debug page memory allocations"
	depends on DEBUG_KERNEL && !HIBERNATION && !HUGETLBFS
	depends on X86_32
	help
	  Unmap pages from the kernel linear mapping after free_pages().
	  This results in a large slowdown, but helps to find certain types
	  of memory corruptions.

config DEBUG_RODATA
	bool "Write protect kernel read-only data structures"
	depends on DEBUG_KERNEL
	help
	  Mark the kernel read-only data as write-protected in the pagetables,
	  in order to catch accidental (and incorrect) writes to such const
	  data. This option may have a slight performance impact because a
	  portion of the kernel code won't be covered by a 2MB TLB anymore.
	  If in doubt, say "N".

config 4KSTACKS
	bool "Use 4Kb for kernel stacks instead of 8Kb"
	depends on DEBUG_KERNEL
	depends on X86_32
	help
	  If you say Y here the kernel will use a 4Kb stacksize for the
	  kernel stack attached to each process/thread. This facilitates
	  running more threads on a system and also reduces the pressure
	  on the VM subsystem for higher order allocations. This option
	  will also use IRQ stacks to compensate for the reduced stackspace.

config X86_FIND_SMP_CONFIG
	def_bool y
	depends on X86_LOCAL_APIC || X86_VOYAGER
	depends on X86_32

config X86_MPPARSE
	def_bool y
	depends on X86_LOCAL_APIC && !X86_VISWS
	depends on X86_32

config DOUBLEFAULT
	default y
	bool "Enable doublefault exception handler" if EMBEDDED
	depends on X86_32
	help
	  This option allows trapping of rare doublefault exceptions that
	  would otherwise cause a system to silently reboot. Disabling this
	  option saves about 4k and might cause you much additional grey
	  hair.

config IOMMU_DEBUG
	bool "Enable IOMMU debugging"
	depends on GART_IOMMU && DEBUG_KERNEL
	depends on X86_64
	help
	  Force the IOMMU to on even when you have less than 4GB of
	  memory and add debugging code. On overflow always panic. And
	  allow to enable IOMMU leak tracing. Can be disabled at boot
	  time with iommu=noforce. This will also enable scatter gather
	  list merging.  Currently not recommended for production
	  code. When you use it make sure you have a big enough
	  IOMMU/AGP aperture.  Most of the options enabled by this can
	  be set more finegrained using the iommu= command line
	  options. See Documentation/x86_64/boot-options.txt for more
	  details.

config IOMMU_LEAK
	bool "IOMMU leak tracing"
	depends on DEBUG_KERNEL
	depends on IOMMU_DEBUG
	help
	  Add a simple leak tracer to the IOMMU code. This is useful when you
	  are debugging a buggy device driver that leaks IOMMU mappings.

endmenu
Commit	Line	Data
1da177e4 LT	1	menu "Kernel hacking"
1da177e4 LT	2
55f327fa	3	config TRACE_IRQFLAGS_SUPPORT
d013a27c	4	def_bool y
55f327fa	5
1da177e4 LT	6	source "lib/Kconfig.debug"
	7
	8	config EARLY_PRINTK
1b8a8e95	9	bool "Early printk" if EMBEDDED && DEBUG_KERNEL && X86_32
1da177e4 LT	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
dab175f3 AB	24	help
	25	This option will cause messages to be printed if free stack space
	26	drops below a certain limit.
1da177e4	27
1da177e4 LT	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"
b0cb1a19	38	depends on DEBUG_KERNEL && HIBERNATION
d013a27c	39	depends on X86_32
1da177e4 LT	40
1da177e4 LT	41	config DEBUG_PAGEALLOC
4a2f0acf	42	bool "Debug page memory allocations"
b0cb1a19	43	depends on DEBUG_KERNEL && !HIBERNATION && !HUGETLBFS
d013a27c	44	depends on X86_32
1da177e4 LT	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
63aaf308 AV	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
1da177e4 LT	60	config 4KSTACKS
	61	bool "Use 4Kb for kernel stacks instead of 8Kb"
	62	depends on DEBUG_KERNEL
d013a27c	63	depends on X86_32
1da177e4 LT	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
d013a27c	72	def_bool y
1da177e4	73	depends on X86_LOCAL_APIC \|\| X86_VOYAGER
d013a27c	74	depends on X86_32
1da177e4 LT	75
1da177e4 LT	76	config X86_MPPARSE
d013a27c	77	def_bool y
1da177e4	78	depends on X86_LOCAL_APIC && !X86_VISWS
d013a27c	79	depends on X86_32
1da177e4	80
102e41fd AK	81	config DOUBLEFAULT
	82	default y
	83	bool "Enable doublefault exception handler" if EMBEDDED
d013a27c RD	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"
966396d3	93	depends on GART_IOMMU && DEBUG_KERNEL
d013a27c	94	depends on X86_64
102e41fd	95	help
d013a27c RD	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
1da177e4	115	endmenu