1menu "Kernel hacking" 2 3source "lib/Kconfig.debug" 4 5config DEBUG_STACKOVERFLOW 6 bool "Check for stack overflows" 7 depends on DEBUG_KERNEL 8 help 9 This option will cause messages to be printed if free stack space 10 drops below a certain limit. 11 12config DEBUG_STACK_USAGE 13 bool "Enable stack utilization instrumentation" 14 depends on DEBUG_KERNEL 15 help 16 Enables the display of the minimum amount of free stack which each 17 task has ever had available in the sysrq-T output. 18 19 This option will slow down process creation somewhat. 20 21config HAVE_ARCH_KGDB 22 def_bool y 23 24config DEBUG_VERBOSE 25 bool "Verbose fault messages" 26 default y 27 select PRINTK 28 help 29 When a program crashes due to an exception, or the kernel detects 30 an internal error, the kernel can print a not so brief message 31 explaining what the problem was. This debugging information is 32 useful to developers and kernel hackers when tracking down problems, 33 but mostly meaningless to other people. This is always helpful for 34 debugging but serves no purpose on a production system. 35 Most people should say N here. 36 37config DEBUG_MMRS 38 bool "Generate Blackfin MMR tree" 39 select DEBUG_FS 40 help 41 Create a tree of Blackfin MMRs via the debugfs tree. If 42 you enable this, you will find all MMRs laid out in the 43 /sys/kernel/debug/blackfin/ directory where you can read/write 44 MMRs directly from userspace. This is obviously just a debug 45 feature. 46 47config DEBUG_HWERR 48 bool "Hardware error interrupt debugging" 49 depends on DEBUG_KERNEL 50 help 51 When enabled, the hardware error interrupt is never disabled, and 52 will happen immediately when an error condition occurs. This comes 53 at a slight cost in code size, but is necessary if you are getting 54 hardware error interrupts and need to know where they are coming 55 from. 56 57config DEBUG_DOUBLEFAULT 58 bool "Debug Double Faults" 59 default n 60 help 61 If an exception is caused while executing code within the exception 62 handler, the NMI handler, the reset vector, or in emulator mode, 63 a double fault occurs. On the Blackfin, this is a unrecoverable 64 event. You have two options: 65 - RESET exactly when double fault occurs. The excepting 66 instruction address is stored in RETX, where the next kernel 67 boot will print it out. 68 - Print debug message. This is much more error prone, although 69 easier to handle. It is error prone since: 70 - The excepting instruction is not committed. 71 - All writebacks from the instruction are prevented. 72 - The generated exception is not taken. 73 - The EXCAUSE field is updated with an unrecoverable event 74 The only way to check this is to see if EXCAUSE contains the 75 unrecoverable event value at every exception return. By selecting 76 this option, you are skipping over the faulting instruction, and 77 hoping things stay together enough to print out a debug message. 78 79 This does add a little kernel code, but is the only method to debug 80 double faults - if unsure say "Y" 81 82choice 83 prompt "Double Fault Failure Method" 84 default DEBUG_DOUBLEFAULT_PRINT 85 depends on DEBUG_DOUBLEFAULT 86 87config DEBUG_DOUBLEFAULT_PRINT 88 bool "Print" 89 90config DEBUG_DOUBLEFAULT_RESET 91 bool "Reset" 92 93endchoice 94 95config DEBUG_ICACHE_CHECK 96 bool "Check Instruction cache coherency" 97 depends on DEBUG_KERNEL 98 depends on DEBUG_HWERR 99 help 100 Say Y here if you are getting weird unexplained errors. This will 101 ensure that icache is what SDRAM says it should be by doing a 102 byte wise comparison between SDRAM and instruction cache. This 103 also relocates the irq_panic() function to L1 memory, (which is 104 un-cached). 105 106config DEBUG_HUNT_FOR_ZERO 107 bool "Catch NULL pointer reads/writes" 108 default y 109 help 110 Say Y here to catch reads/writes to anywhere in the memory range 111 from 0x0000 - 0x0FFF (the first 4k) of memory. This is useful in 112 catching common programming errors such as NULL pointer dereferences. 113 114 Misbehaving applications will be killed (generate a SEGV) while the 115 kernel will trigger a panic. 116 117 Enabling this option will take up an extra entry in CPLB table. 118 Otherwise, there is no extra overhead. 119 120config DEBUG_BFIN_HWTRACE_ON 121 bool "Turn on Blackfin's Hardware Trace" 122 default y 123 help 124 All Blackfins include a Trace Unit which stores a history of the last 125 16 changes in program flow taken by the program sequencer. The history 126 allows the user to recreate the program sequencer\xE2\x80\x99s recent path. This 127 can be handy when an application dies - we print out the execution 128 path of how it got to the offending instruction. 129 130 By turning this off, you may save a tiny amount of power. 131 132choice 133 prompt "Omit loop Tracing" 134 default DEBUG_BFIN_HWTRACE_COMPRESSION_OFF 135 depends on DEBUG_BFIN_HWTRACE_ON 136 help 137 The trace buffer can be configured to omit recording of changes in 138 program flow that match either the last entry or one of the last 139 two entries. Omitting one of these entries from the record prevents 140 the trace buffer from overflowing because of any sort of loop (for, do 141 while, etc) in the program. 142 143 Because zero-overhead Hardware loops are not recorded in the trace buffer, 144 this feature can be used to prevent trace overflow from loops that 145 are nested four deep. 146 147config DEBUG_BFIN_HWTRACE_COMPRESSION_OFF 148 bool "Trace all Loops" 149 help 150 The trace buffer records all changes of flow 151 152config DEBUG_BFIN_HWTRACE_COMPRESSION_ONE 153 bool "Compress single-level loops" 154 help 155 The trace buffer does not record single loops - helpful if trace 156 is spinning on a while or do loop. 157 158config DEBUG_BFIN_HWTRACE_COMPRESSION_TWO 159 bool "Compress two-level loops" 160 help 161 The trace buffer does not record loops two levels deep. Helpful if 162 the trace is spinning in a nested loop 163 164endchoice 165 166config DEBUG_BFIN_HWTRACE_COMPRESSION 167 int 168 depends on DEBUG_BFIN_HWTRACE_ON 169 default 0 if DEBUG_BFIN_HWTRACE_COMPRESSION_OFF 170 default 1 if DEBUG_BFIN_HWTRACE_COMPRESSION_ONE 171 default 2 if DEBUG_BFIN_HWTRACE_COMPRESSION_TWO 172 173 174config DEBUG_BFIN_HWTRACE_EXPAND 175 bool "Expand Trace Buffer greater than 16 entries" 176 depends on DEBUG_BFIN_HWTRACE_ON 177 default n 178 help 179 By selecting this option, every time the 16 hardware entries in 180 the Blackfin's HW Trace buffer are full, the kernel will move them 181 into a software buffer, for dumping when there is an issue. This 182 has a great impact on performance, (an interrupt every 16 change of 183 flows) and should normally be turned off, except in those nasty 184 debugging sessions 185 186config DEBUG_BFIN_HWTRACE_EXPAND_LEN 187 int "Size of Trace buffer (in power of 2k)" 188 range 0 4 189 depends on DEBUG_BFIN_HWTRACE_EXPAND 190 default 1 191 help 192 This sets the size of the software buffer that the trace information 193 is kept in. 194 0 for (2^0) 1k, or 256 entries, 195 1 for (2^1) 2k, or 512 entries, 196 2 for (2^2) 4k, or 1024 entries, 197 3 for (2^3) 8k, or 2048 entries, 198 4 for (2^4) 16k, or 4096 entries 199 200config DEBUG_BFIN_NO_KERN_HWTRACE 201 bool "Turn off hwtrace in CPLB handlers" 202 depends on DEBUG_BFIN_HWTRACE_ON 203 default y 204 help 205 The CPLB error handler contains a lot of flow changes which can 206 quickly fill up the hardware trace buffer. When debugging crashes, 207 the hardware trace may indicate that the problem lies in kernel 208 space when in reality an application is buggy. 209 210 Say Y here to disable hardware tracing in some known "jumpy" pieces 211 of code so that the trace buffer will extend further back. 212 213config EARLY_PRINTK 214 bool "Early printk" 215 default n 216 select SERIAL_CORE_CONSOLE 217 help 218 This option enables special console drivers which allow the kernel 219 to print messages very early in the bootup process. 220 221 This is useful for kernel debugging when your machine crashes very 222 early before the console code is initialized. After enabling this 223 feature, you must add "earlyprintk=serial,uart0,57600" to the 224 command line (bootargs). It is safe to say Y here in all cases, as 225 all of this lives in the init section and is thrown away after the 226 kernel boots completely. 227 228config CPLB_INFO 229 bool "Display the CPLB information" 230 help 231 Display the CPLB information via /proc/cplbinfo. 232 233config ACCESS_CHECK 234 bool "Check the user pointer address" 235 default y 236 help 237 Usually the pointer transfer from user space is checked to see if its 238 address is in the kernel space. 239 240 Say N here to disable that check to improve the performance. 241 242endmenu 243