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 DEBUG_VERBOSE 22 bool "Verbose fault messages" 23 default y 24 select PRINTK 25 help 26 When a program crashes due to an exception, or the kernel detects 27 an internal error, the kernel can print a not so brief message 28 explaining what the problem was. This debugging information is 29 useful to developers and kernel hackers when tracking down problems, 30 but mostly meaningless to other people. This is always helpful for 31 debugging but serves no purpose on a production system. 32 Most people should say N here. 33 34config DEBUG_MMRS 35 bool "Generate Blackfin MMR tree" 36 select DEBUG_FS 37 help 38 Create a tree of Blackfin MMRs via the debugfs tree. If 39 you enable this, you will find all MMRs laid out in the 40 /sys/kernel/debug/blackfin/ directory where you can read/write 41 MMRs directly from userspace. This is obviously just a debug 42 feature. 43 44config DEBUG_HWERR 45 bool "Hardware error interrupt debugging" 46 depends on DEBUG_KERNEL 47 help 48 When enabled, the hardware error interrupt is never disabled, and 49 will happen immediately when an error condition occurs. This comes 50 at a slight cost in code size, but is necessary if you are getting 51 hardware error interrupts and need to know where they are coming 52 from. 53 54config EXACT_HWERR 55 bool "Try to make Hardware errors exact" 56 depends on DEBUG_HWERR 57 help 58 By default, the Blackfin hardware errors are not exact - the error 59 be reported multiple cycles after the error happens. This delay 60 can cause the wrong application, or even the kernel to receive a 61 signal to be killed. If you are getting HW errors in your system, 62 try turning this on to ensure they are at least comming from the 63 proper thread. 64 65 On production systems, it is safe (and a small optimization) to say N. 66 67config DEBUG_DOUBLEFAULT 68 bool "Debug Double Faults" 69 default n 70 help 71 If an exception is caused while executing code within the exception 72 handler, the NMI handler, the reset vector, or in emulator mode, 73 a double fault occurs. On the Blackfin, this is a unrecoverable 74 event. You have two options: 75 - RESET exactly when double fault occurs. The excepting 76 instruction address is stored in RETX, where the next kernel 77 boot will print it out. 78 - Print debug message. This is much more error prone, although 79 easier to handle. It is error prone since: 80 - The excepting instruction is not committed. 81 - All writebacks from the instruction are prevented. 82 - The generated exception is not taken. 83 - The EXCAUSE field is updated with an unrecoverable event 84 The only way to check this is to see if EXCAUSE contains the 85 unrecoverable event value at every exception return. By selecting 86 this option, you are skipping over the faulting instruction, and 87 hoping things stay together enough to print out a debug message. 88 89 This does add a little kernel code, but is the only method to debug 90 double faults - if unsure say "Y" 91 92choice 93 prompt "Double Fault Failure Method" 94 default DEBUG_DOUBLEFAULT_PRINT 95 depends on DEBUG_DOUBLEFAULT 96 97config DEBUG_DOUBLEFAULT_PRINT 98 bool "Print" 99 100config DEBUG_DOUBLEFAULT_RESET 101 bool "Reset" 102 103endchoice 104 105config DEBUG_HUNT_FOR_ZERO 106 bool "Catch NULL pointer reads/writes" 107 default y 108 help 109 Say Y here to catch reads/writes to anywhere in the memory range 110 from 0x0000 - 0x0FFF (the first 4k) of memory. This is useful in 111 catching common programming errors such as NULL pointer dereferences. 112 113 Misbehaving applications will be killed (generate a SEGV) while the 114 kernel will trigger a panic. 115 116 Enabling this option will take up an extra entry in CPLB table. 117 Otherwise, there is no extra overhead. 118 119config DEBUG_BFIN_HWTRACE_ON 120 bool "Turn on Blackfin's Hardware Trace" 121 default y 122 help 123 All Blackfins include a Trace Unit which stores a history of the last 124 16 changes in program flow taken by the program sequencer. The history 125 allows the user to recreate the program sequencer’s recent path. This 126 can be handy when an application dies - we print out the execution 127 path of how it got to the offending instruction. 128 129 By turning this off, you may save a tiny amount of power. 130 131choice 132 prompt "Omit loop Tracing" 133 default DEBUG_BFIN_HWTRACE_COMPRESSION_OFF 134 depends on DEBUG_BFIN_HWTRACE_ON 135 help 136 The trace buffer can be configured to omit recording of changes in 137 program flow that match either the last entry or one of the last 138 two entries. Omitting one of these entries from the record prevents 139 the trace buffer from overflowing because of any sort of loop (for, do 140 while, etc) in the program. 141 142 Because zero-overhead Hardware loops are not recorded in the trace buffer, 143 this feature can be used to prevent trace overflow from loops that 144 are nested four deep. 145 146config DEBUG_BFIN_HWTRACE_COMPRESSION_OFF 147 bool "Trace all Loops" 148 help 149 The trace buffer records all changes of flow 150 151config DEBUG_BFIN_HWTRACE_COMPRESSION_ONE 152 bool "Compress single-level loops" 153 help 154 The trace buffer does not record single loops - helpful if trace 155 is spinning on a while or do loop. 156 157config DEBUG_BFIN_HWTRACE_COMPRESSION_TWO 158 bool "Compress two-level loops" 159 help 160 The trace buffer does not record loops two levels deep. Helpful if 161 the trace is spinning in a nested loop 162 163endchoice 164 165config DEBUG_BFIN_HWTRACE_COMPRESSION 166 int 167 depends on DEBUG_BFIN_HWTRACE_ON 168 default 0 if DEBUG_BFIN_HWTRACE_COMPRESSION_OFF 169 default 1 if DEBUG_BFIN_HWTRACE_COMPRESSION_ONE 170 default 2 if DEBUG_BFIN_HWTRACE_COMPRESSION_TWO 171 172 173config DEBUG_BFIN_HWTRACE_EXPAND 174 bool "Expand Trace Buffer greater than 16 entries" 175 depends on DEBUG_BFIN_HWTRACE_ON 176 default n 177 help 178 By selecting this option, every time the 16 hardware entries in 179 the Blackfin's HW Trace buffer are full, the kernel will move them 180 into a software buffer, for dumping when there is an issue. This 181 has a great impact on performance, (an interrupt every 16 change of 182 flows) and should normally be turned off, except in those nasty 183 debugging sessions 184 185config DEBUG_BFIN_HWTRACE_EXPAND_LEN 186 int "Size of Trace buffer (in power of 2k)" 187 range 0 4 188 depends on DEBUG_BFIN_HWTRACE_EXPAND 189 default 1 190 help 191 This sets the size of the software buffer that the trace information 192 is kept in. 193 0 for (2^0) 1k, or 256 entries, 194 1 for (2^1) 2k, or 512 entries, 195 2 for (2^2) 4k, or 1024 entries, 196 3 for (2^3) 8k, or 2048 entries, 197 4 for (2^4) 16k, or 4096 entries 198 199config DEBUG_BFIN_NO_KERN_HWTRACE 200 bool "Turn off hwtrace in CPLB handlers" 201 depends on DEBUG_BFIN_HWTRACE_ON 202 default y 203 help 204 The CPLB error handler contains a lot of flow changes which can 205 quickly fill up the hardware trace buffer. When debugging crashes, 206 the hardware trace may indicate that the problem lies in kernel 207 space when in reality an application is buggy. 208 209 Say Y here to disable hardware tracing in some known "jumpy" pieces 210 of code so that the trace buffer will extend further back. 211 212config EARLY_PRINTK 213 bool "Early printk" 214 default n 215 select SERIAL_CORE_CONSOLE 216 help 217 This option enables special console drivers which allow the kernel 218 to print messages very early in the bootup process. 219 220 This is useful for kernel debugging when your machine crashes very 221 early before the console code is initialized. After enabling this 222 feature, you must add "earlyprintk=serial,uart0,57600" to the 223 command line (bootargs). It is safe to say Y here in all cases, as 224 all of this lives in the init section and is thrown away after the 225 kernel boots completely. 226 227config NMI_WATCHDOG 228 bool "Enable NMI watchdog to help debugging lockup on SMP" 229 default n 230 depends on SMP 231 help 232 If any CPU in the system does not execute the period local timer 233 interrupt for more than 5 seconds, then the NMI handler dumps debug 234 information. This information can be used to debug the lockup. 235 236config CPLB_INFO 237 bool "Display the CPLB information" 238 help 239 Display the CPLB information via /proc/cplbinfo. 240 241config ACCESS_CHECK 242 bool "Check the user pointer address" 243 default y 244 help 245 Usually the pointer transfer from user space is checked to see if its 246 address is in the kernel space. 247 248 Say N here to disable that check to improve the performance. 249 250config BFIN_ISRAM_SELF_TEST 251 bool "isram boot self tests" 252 default n 253 help 254 Run some self tests of the isram driver code at boot. 255 256config BFIN_PSEUDODBG_INSNS 257 bool "Support pseudo debug instructions" 258 default n 259 help 260 This option allows the kernel to emulate some pseudo instructions which 261 allow simulator test cases to be run under Linux with no changes. 262 263 Most people should say N here. 264 265endmenu 266