menu "Kernel hacking" config TRACE_IRQFLAGS_SUPPORT	def_bool y source "lib/Kconfig.debug" config STRICT_DEVMEM	bool "Filter access to /dev/mem"	---help---	  If this option is disabled, you allow userspace (root) access to all	  of memory, including kernel and userspace memory. Accidental	  access to this is obviously disastrous, but specific access can	  be used by people debugging the kernel. Note that with PAT support	  enabled, even in this case there are restrictions on /dev/mem	  use due to the cache aliasing requirements. 	  If this option is switched on, the /dev/mem file only allows	  userspace access to PCI space and the BIOS code and data regions.	  This is sufficient for dosemu and X and all common users of	  /dev/mem. 	  If in doubt, say Y. config X86_VERBOSE_BOOTUP	bool "Enable verbose x86 bootup info messages"	default y	---help---	  Enables the informational output from the decompression stage	  (e.g. bzImage) of the boot. If you disable this you will still	  see errors. Disable this if you want silent bootup. config EARLY_PRINTK	bool "Early printk" if EXPERT	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 EARLY_PRINTK_INTEL_MID	bool "Early printk for Intel MID platform support"	depends on EARLY_PRINTK && X86_INTEL_MID config EARLY_PRINTK_DBGP	bool "Early printk via EHCI debug port"	depends on EARLY_PRINTK && PCI	---help---	  Write kernel log output directly into the EHCI debug 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. You need usb debug device. config DEBUG_STACKOVERFLOW	bool "Check for stack overflows"	depends on DEBUG_KERNEL	---help---	  Say Y here if you want to check the overflows of kernel, IRQ	  and exception stacks. This option will cause messages of the	  stacks in detail when free stack space drops below a certain	  limit.	  If in doubt, say "N". config X86_PTDUMP	bool "Export kernel pagetable layout to userspace via debugfs"	depends on DEBUG_KERNEL	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	default y	---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_SET_MODULE_RONX	bool "Set loadable kernel module data as NX and text as RO"	depends on MODULES	---help---	  This option helps catch unintended modifications to loadable	  kernel module's text and read-only data. It also prevents execution	  of module data. Such protection may interfere with run-time code	  patching and dynamic kernel tracing - and they might also protect	  against certain classes of kernel exploits.	  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 DOUBLEFAULT	default y	bool "Enable doublefault exception handler" if EXPERT	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/x86_64/boot-options.txt for more	  details. config IOMMU_STRESS	bool "Enable IOMMU stress-test mode"	---help---	  This option disables various optimizations in IOMMU related	  code to do real stress testing of the IOMMU code. This option	  will cause a performance drop and should only be enabled for	  testing. config IOMMU_LEAK	bool "IOMMU leak tracing"	depends on IOMMU_DEBUG && DMA_API_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. config HAVE_MMIOTRACE_SUPPORT	def_bool y config X86_DECODER_SELFTEST	bool "x86 instruction decoder selftest"	depends on DEBUG_KERNEL && KPROBES	---help---	 Perform x86 instruction decoder selftests at build time.	 This option is useful for checking the sanity of x86 instruction	 decoder code.	 If unsure, say "N". ## 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_0X80config DEFAULT_IO_DELAY_TYPE	int	default IO_DELAY_TYPE_0X80endif if IO_DELAY_0XEDconfig DEFAULT_IO_DELAY_TYPE	int	default IO_DELAY_TYPE_0XEDendif if IO_DELAY_UDELAYconfig DEFAULT_IO_DELAY_TYPE	int	default IO_DELAY_TYPE_UDELAYendif if IO_DELAY_NONEconfig DEFAULT_IO_DELAY_TYPE	int	default IO_DELAY_TYPE_NONEendif 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. config OPTIMIZE_INLINING	bool "Allow gcc to uninline functions marked 'inline'"	---help---	  This option determines if the kernel forces gcc to inline the functions	  developers have marked 'inline'. Doing so takes away freedom from gcc to	  do what it thinks is best, which is desirable for the gcc 3.x series of	  compilers. The gcc 4.x series have a rewritten inlining algorithm and	  enabling this option will generate a smaller kernel there. Hopefully	  this algorithm is so good that allowing gcc 4.x and above to make the	  decision will become the default in the future. Until then this option	  is there to test gcc for this. 	  If unsure, say N. config DEBUG_STRICT_USER_COPY_CHECKS	bool "Strict copy size checks"	depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING	---help---	  Enabling this option turns a certain set of sanity checks for user	  copy operations into compile time failures. 	  The copy_from_user() etc checks are there to help test if there	  are sufficient security checks on the length argument of	  the copy operation, by having gcc prove that the argument is	  within bounds. 	  If unsure, or if you run an older (pre 4.4) gcc, say N. config DEBUG_NMI_SELFTEST	bool "NMI Selftest"	depends on DEBUG_KERNEL && X86_LOCAL_APIC	---help---	  Enabling this option turns on a quick NMI selftest to verify	  that the NMI behaves correctly. 	  This might help diagnose strange hangs that rely on NMI to	  function properly. 	  If unsure, say N. endmenu