[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
	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.

config DEBUG_PAGEALLOC
	bool "Debug page memory allocations"
	depends on DEBUG_KERNEL
	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_PER_CPU_MAPS
	bool "Debug access to per_cpu maps"
	depends on DEBUG_KERNEL
	depends on X86_64_SMP
	default n
	help
	  Say Y to verify that the per_cpu map being accessed has
	  been setup.  Adds a fair amount of code to kernel memory
	  and decreases performance.

	  Say N if unsure.

config X86_PTDUMP
	bool "Export kernel pagetable layout to userspace via debugfs"
	depends on X86_64
	select DEBUG_FS
	help
	  Say Y here if you want to show the kernel pagetable layout in a
	  debugfs file. This information is only useful for kernel developers
	  who are working in architecture specific areas of the kernel.
	  It is probably not a good idea to enable this feature in a production
	  kernel.
	  If in doubt, say "N"

config DEBUG_RODATA
	bool "Write protect kernel read-only data structures"
	default y
	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 is recommended so that we can catch kernel bugs sooner.
	  If in doubt, say "Y".

config DEBUG_RODATA_TEST
	bool "Testcase for the DEBUG_RODATA feature"
	depends on DEBUG_RODATA
	help
	  This option enables a testcase for the DEBUG_RODATA
	  feature as well as for the change_page_attr() infrastructure.
	  If in doubt, say "N"

config DEBUG_NX_TEST
	tristate "Testcase for the NX non-executable stack feature"
	depends on DEBUG_KERNEL && m
	help
	  This option enables a testcase for the CPU NX capability
	  and the software setup of this feature.
	  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_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

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.

config CPA_DEBUG
	bool "CPA self-test code"
	depends on DEBUG_KERNEL
	help
	  Do change_page_attr() self-tests every 30 seconds.

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
1da177e4	37	config DEBUG_PAGEALLOC
4a2f0acf	38	bool "Debug page memory allocations"
b1d95f4e	39	depends on DEBUG_KERNEL
1da177e4 LT	40	help
	41	Unmap pages from the kernel linear mapping after free_pages().
	42	This results in a large slowdown, but helps to find certain types
	43	of memory corruptions.
	44
c49a4955	45	config DEBUG_PER_CPU_MAPS
	46	bool "Debug access to per_cpu maps"
	47	depends on DEBUG_KERNEL
	48	depends on X86_64_SMP
	49	default n
	50	help
	51	Say Y to verify that the per_cpu map being accessed has
	52	been setup. Adds a fair amount of code to kernel memory
	53	and decreases performance.
	54
	55	Say N if unsure.
	56
926e5392 AV	57	config X86_PTDUMP
	58	bool "Export kernel pagetable layout to userspace via debugfs"
	59	depends on X86_64
	60	select DEBUG_FS
	61	help
	62	Say Y here if you want to show the kernel pagetable layout in a
	63	debugfs file. This information is only useful for kernel developers
	64	who are working in architecture specific areas of the kernel.
	65	It is probably not a good idea to enable this feature in a production
	66	kernel.
	67	If in doubt, say "N"
	68
63aaf308 AV	69	config DEBUG_RODATA
63aaf308 AV	70	bool "Write protect kernel read-only data structures"
11201e60	71	default y
63aaf308 AV	72	depends on DEBUG_KERNEL
	73	help
	74	Mark the kernel read-only data as write-protected in the pagetables,
	75	in order to catch accidental (and incorrect) writes to such const
11201e60 IM	76	data. This is recommended so that we can catch kernel bugs sooner.
11201e60 IM	77	If in doubt, say "Y".
63aaf308	78
aba8391f IM	79	config DEBUG_RODATA_TEST
	80	bool "Testcase for the DEBUG_RODATA feature"
	81	depends on DEBUG_RODATA
	82	help
	83	This option enables a testcase for the DEBUG_RODATA
	84	feature as well as for the change_page_attr() infrastructure.
	85	If in doubt, say "N"
	86
	87	config DEBUG_NX_TEST
	88	tristate "Testcase for the NX non-executable stack feature"
	89	depends on DEBUG_KERNEL && m
	90	help
	91	This option enables a testcase for the CPU NX capability
	92	and the software setup of this feature.
	93	If in doubt, say "N"
	94
1da177e4 LT	95	config 4KSTACKS
	96	bool "Use 4Kb for kernel stacks instead of 8Kb"
	97	depends on DEBUG_KERNEL
d013a27c	98	depends on X86_32
1da177e4 LT	99	help
	100	If you say Y here the kernel will use a 4Kb stacksize for the
	101	kernel stack attached to each process/thread. This facilitates
	102	running more threads on a system and also reduces the pressure
	103	on the VM subsystem for higher order allocations. This option
	104	will also use IRQ stacks to compensate for the reduced stackspace.
	105
	106	config X86_FIND_SMP_CONFIG
d013a27c	107	def_bool y
1da177e4	108	depends on X86_LOCAL_APIC \|\| X86_VOYAGER
d013a27c	109	depends on X86_32
1da177e4 LT	110
1da177e4 LT	111	config X86_MPPARSE
d013a27c	112	def_bool y
6b0c3d44	113	depends on (X86_32 && (X86_LOCAL_APIC && !X86_VISWS)) \|\| X86_64
1da177e4	114
102e41fd AK	115	config DOUBLEFAULT
	116	default y
	117	bool "Enable doublefault exception handler" if EMBEDDED
d013a27c RD	118	depends on X86_32
	119	help
	120	This option allows trapping of rare doublefault exceptions that
	121	would otherwise cause a system to silently reboot. Disabling this
	122	option saves about 4k and might cause you much additional grey
	123	hair.
	124
	125	config IOMMU_DEBUG
	126	bool "Enable IOMMU debugging"
966396d3	127	depends on GART_IOMMU && DEBUG_KERNEL
d013a27c	128	depends on X86_64
102e41fd	129	help
d013a27c RD	130	Force the IOMMU to on even when you have less than 4GB of
	131	memory and add debugging code. On overflow always panic. And
	132	allow to enable IOMMU leak tracing. Can be disabled at boot
	133	time with iommu=noforce. This will also enable scatter gather
	134	list merging. Currently not recommended for production
	135	code. When you use it make sure you have a big enough
	136	IOMMU/AGP aperture. Most of the options enabled by this can
	137	be set more finegrained using the iommu= command line
	138	options. See Documentation/x86_64/boot-options.txt for more
	139	details.
	140
	141	config IOMMU_LEAK
	142	bool "IOMMU leak tracing"
	143	depends on DEBUG_KERNEL
	144	depends on IOMMU_DEBUG
	145	help
	146	Add a simple leak tracer to the IOMMU code. This is useful when you
	147	are debugging a buggy device driver that leaks IOMMU mappings.
	148
6e7c4025 IM	149	#
	150	# IO delay types:
	151	#
	152
	153	config IO_DELAY_TYPE_0X80
	154	int
	155	default "0"
	156
	157	config IO_DELAY_TYPE_0XED
	158	int
	159	default "1"
	160
	161	config IO_DELAY_TYPE_UDELAY
	162	int
	163	default "2"
	164
	165	config IO_DELAY_TYPE_NONE
	166	int
	167	default "3"
	168
	169	choice
	170	prompt "IO delay type"
fd59e9e9	171	default IO_DELAY_0X80
6e7c4025 IM	172
	173	config IO_DELAY_0X80
	174	bool "port 0x80 based port-IO delay [recommended]"
	175	help
	176	This is the traditional Linux IO delay used for in/out_p.
	177	It is the most tested hence safest selection here.
	178
	179	config IO_DELAY_0XED
	180	bool "port 0xed based port-IO delay"
	181	help
	182	Use port 0xed as the IO delay. This frees up port 0x80 which is
	183	often used as a hardware-debug port.
	184
	185	config IO_DELAY_UDELAY
	186	bool "udelay based port-IO delay"
	187	help
	188	Use udelay(2) as the IO delay method. This provides the delay
	189	while not having any side-effect on the IO port space.
	190
	191	config IO_DELAY_NONE
	192	bool "no port-IO delay"
b02aae9c	193	help
6e7c4025 IM	194	No port-IO delay. Will break on old boxes that require port-IO
	195	delay for certain operations. Should work on most new machines.
	196
	197	endchoice
	198
	199	if IO_DELAY_0X80
	200	config DEFAULT_IO_DELAY_TYPE
	201	int
	202	default IO_DELAY_TYPE_0X80
	203	endif
	204
	205	if IO_DELAY_0XED
	206	config DEFAULT_IO_DELAY_TYPE
	207	int
	208	default IO_DELAY_TYPE_0XED
	209	endif
	210
	211	if IO_DELAY_UDELAY
	212	config DEFAULT_IO_DELAY_TYPE
	213	int
	214	default IO_DELAY_TYPE_UDELAY
	215	endif
	216
	217	if IO_DELAY_NONE
	218	config DEFAULT_IO_DELAY_TYPE
	219	int
	220	default IO_DELAY_TYPE_NONE
	221	endif
b02aae9c	222
6d7d7433 HY	223	config DEBUG_BOOT_PARAMS
	224	bool "Debug boot parameters"
	225	depends on DEBUG_KERNEL
	226	depends on DEBUG_FS
	227	help
	228	This option will cause struct boot_params to be exported via debugfs.
	229
0c42f392	230	config CPA_DEBUG
971a52d6	231	bool "CPA self-test code"
f316fe68	232	depends on DEBUG_KERNEL
0c42f392	233	help
971a52d6	234	Do change_page_attr() self-tests every 30 seconds.
0c42f392	235
1da177e4	236	endmenu