1menu "Kernel hacking" 2 3config TRACE_IRQFLAGS_SUPPORT 4 def_bool y 5 6source "lib/Kconfig.debug" 7 8config EARLY_PRINTK 9 bool "Early printk" if EMBEDDED && DEBUG_KERNEL && X86_32 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 21config DEBUG_STACKOVERFLOW 22 bool "Check for stack overflows" 23 depends on DEBUG_KERNEL 24 help 25 This option will cause messages to be printed if free stack space 26 drops below a certain limit. 27 28config 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 37comment "Page alloc debug is incompatible with Software Suspend on i386" 38 depends on DEBUG_KERNEL && HIBERNATION 39 depends on X86_32 40 41config DEBUG_PAGEALLOC 42 bool "Debug page memory allocations" 43 depends on DEBUG_KERNEL && !HIBERNATION && !HUGETLBFS 44 depends on X86_32 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 50config 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 60config 4KSTACKS 61 bool "Use 4Kb for kernel stacks instead of 8Kb" 62 depends on DEBUG_KERNEL 63 depends on X86_32 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 71config X86_FIND_SMP_CONFIG 72 def_bool y 73 depends on X86_LOCAL_APIC || X86_VOYAGER 74 depends on X86_32 75 76config X86_MPPARSE 77 def_bool y 78 depends on X86_LOCAL_APIC && !X86_VISWS 79 depends on X86_32 80 81config DOUBLEFAULT 82 default y 83 bool "Enable doublefault exception handler" if EMBEDDED 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 91config IOMMU_DEBUG 92 bool "Enable IOMMU debugging" 93 depends on GART_IOMMU && DEBUG_KERNEL 94 depends on X86_64 95 help 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 107config 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 115endmenu 116