[deliverable/linux.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
	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_32 && (X86_LOCAL_APIC && !X86_VISWS)) || X86_64

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.

#
# IO delay types:
#

config IO_DELAY_TYPE_0X80
	int
	default "0"

config IO_DELAY_TYPE_0XED
	int
	default "1"

config IO_DELAY_TYPE_UDELAY
	int
	default "2"

config IO_DELAY_TYPE_NONE
	int
	default "3"

choice
	prompt "IO delay type"
	default IO_DELAY_0XED

config IO_DELAY_0X80
	bool "port 0x80 based port-IO delay [recommended]"
	help
	  This is the traditional Linux IO delay used for in/out_p.
	  It is the most tested hence safest selection here.

config IO_DELAY_0XED
	bool "port 0xed based port-IO delay"
	help
	  Use port 0xed as the IO delay. This frees up port 0x80 which is
	  often used as a hardware-debug port.

config IO_DELAY_UDELAY
	bool "udelay based port-IO delay"
	help
	  Use udelay(2) as the IO delay method. This provides the delay
	  while not having any side-effect on the IO port space.

config IO_DELAY_NONE
	bool "no port-IO delay"
	help
	  No port-IO delay. Will break on old boxes that require port-IO
	  delay for certain operations. Should work on most new machines.

endchoice

if IO_DELAY_0X80
config DEFAULT_IO_DELAY_TYPE
	int
	default IO_DELAY_TYPE_0X80
endif

if IO_DELAY_0XED
config DEFAULT_IO_DELAY_TYPE
	int
	default IO_DELAY_TYPE_0XED
endif

if IO_DELAY_UDELAY
config DEFAULT_IO_DELAY_TYPE
	int
	default IO_DELAY_TYPE_UDELAY
endif

if IO_DELAY_NONE
config DEFAULT_IO_DELAY_TYPE
	int
	default IO_DELAY_TYPE_NONE
endif

config DEBUG_BOOT_PARAMS
	bool "Debug boot parameters"
	depends on DEBUG_KERNEL
	depends on DEBUG_FS
	help
	  This option will cause struct boot_params to be exported via debugfs.

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
076f9776	9	bool "Early printk" if EMBEDDED
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
6b0c3d44	78	depends on (X86_32 && (X86_LOCAL_APIC && !X86_VISWS)) \|\| X86_64
1da177e4	79
102e41fd AK	80	config DOUBLEFAULT
	81	default y
	82	bool "Enable doublefault exception handler" if EMBEDDED
d013a27c RD	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"
966396d3	92	depends on GART_IOMMU && DEBUG_KERNEL
d013a27c	93	depends on X86_64
102e41fd	94	help
d013a27c RD	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
6e7c4025 IM	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"
d0049e71	136	default IO_DELAY_0XED
6e7c4025 IM	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"
b02aae9c	158	help
6e7c4025 IM	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
b02aae9c	187
6d7d7433 HY	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
1da177e4	195	endmenu