[linux-2.6-block.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.

#
# 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_0X80

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

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
6e7c4025 IM	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"
b02aae9c	159	help
6e7c4025 IM	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
b02aae9c	188
1da177e4	189	endmenu