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