1menu "Kernel hacking" 2 3source "lib/Kconfig.debug" 4 5config DEBUG_VERBOSE 6 bool "Verbose fault messages" 7 default y 8 select PRINTK 9 help 10 When a program crashes due to an exception, or the kernel detects 11 an internal error, the kernel can print a not so brief message 12 explaining what the problem was. This debugging information is 13 useful to developers and kernel hackers when tracking down problems, 14 but mostly meaningless to other people. This is always helpful for 15 debugging but serves no purpose on a production system. 16 Most people should say N here. 17 18config DEBUG_MMRS 19 tristate "Generate Blackfin MMR tree" 20 depends on !PINCTRL 21 select DEBUG_FS 22 help 23 Create a tree of Blackfin MMRs via the debugfs tree. If 24 you enable this, you will find all MMRs laid out in the 25 /sys/kernel/debug/blackfin/ directory where you can read/write 26 MMRs directly from userspace. This is obviously just a debug 27 feature. 28 29config DEBUG_HWERR 30 bool "Hardware error interrupt debugging" 31 depends on DEBUG_KERNEL 32 help 33 When enabled, the hardware error interrupt is never disabled, and 34 will happen immediately when an error condition occurs. This comes 35 at a slight cost in code size, but is necessary if you are getting 36 hardware error interrupts and need to know where they are coming 37 from. 38 39config EXACT_HWERR 40 bool "Try to make Hardware errors exact" 41 depends on DEBUG_HWERR 42 help 43 By default, the Blackfin hardware errors are not exact - the error 44 be reported multiple cycles after the error happens. This delay 45 can cause the wrong application, or even the kernel to receive a 46 signal to be killed. If you are getting HW errors in your system, 47 try turning this on to ensure they are at least coming from the 48 proper thread. 49 50 On production systems, it is safe (and a small optimization) to say N. 51 52config DEBUG_DOUBLEFAULT 53 bool "Debug Double Faults" 54 default n 55 help 56 If an exception is caused while executing code within the exception 57 handler, the NMI handler, the reset vector, or in emulator mode, 58 a double fault occurs. On the Blackfin, this is a unrecoverable 59 event. You have two options: 60 - RESET exactly when double fault occurs. The excepting 61 instruction address is stored in RETX, where the next kernel 62 boot will print it out. 63 - Print debug message. This is much more error prone, although 64 easier to handle. It is error prone since: 65 - The excepting instruction is not committed. 66 - All writebacks from the instruction are prevented. 67 - The generated exception is not taken. 68 - The EXCAUSE field is updated with an unrecoverable event 69 The only way to check this is to see if EXCAUSE contains the 70 unrecoverable event value at every exception return. By selecting 71 this option, you are skipping over the faulting instruction, and 72 hoping things stay together enough to print out a debug message. 73 74 This does add a little kernel code, but is the only method to debug 75 double faults - if unsure say "Y" 76 77choice 78 prompt "Double Fault Failure Method" 79 default DEBUG_DOUBLEFAULT_PRINT 80 depends on DEBUG_DOUBLEFAULT 81 82config DEBUG_DOUBLEFAULT_PRINT 83 bool "Print" 84 85config DEBUG_DOUBLEFAULT_RESET 86 bool "Reset" 87 88endchoice 89 90config DEBUG_HUNT_FOR_ZERO 91 bool "Catch NULL pointer reads/writes" 92 default y 93 help 94 Say Y here to catch reads/writes to anywhere in the memory range 95 from 0x0000 - 0x0FFF (the first 4k) of memory. This is useful in 96 catching common programming errors such as NULL pointer dereferences. 97 98 Misbehaving applications will be killed (generate a SEGV) while the 99 kernel will trigger a panic. 100 101 Enabling this option will take up an extra entry in CPLB table. 102 Otherwise, there is no extra overhead. 103 104config DEBUG_BFIN_HWTRACE_ON 105 bool "Turn on Blackfin's Hardware Trace" 106 default y 107 help 108 All Blackfins include a Trace Unit which stores a history of the last 109 16 changes in program flow taken by the program sequencer. The history 110 allows the user to recreate the program sequencer’s recent path. This 111 can be handy when an application dies - we print out the execution 112 path of how it got to the offending instruction. 113 114 By turning this off, you may save a tiny amount of power. 115 116choice 117 prompt "Omit loop Tracing" 118 default DEBUG_BFIN_HWTRACE_COMPRESSION_OFF 119 depends on DEBUG_BFIN_HWTRACE_ON 120 help 121 The trace buffer can be configured to omit recording of changes in 122 program flow that match either the last entry or one of the last 123 two entries. Omitting one of these entries from the record prevents 124 the trace buffer from overflowing because of any sort of loop (for, do 125 while, etc) in the program. 126 127 Because zero-overhead Hardware loops are not recorded in the trace buffer, 128 this feature can be used to prevent trace overflow from loops that 129 are nested four deep. 130 131config DEBUG_BFIN_HWTRACE_COMPRESSION_OFF 132 bool "Trace all Loops" 133 help 134 The trace buffer records all changes of flow 135 136config DEBUG_BFIN_HWTRACE_COMPRESSION_ONE 137 bool "Compress single-level loops" 138 help 139 The trace buffer does not record single loops - helpful if trace 140 is spinning on a while or do loop. 141 142config DEBUG_BFIN_HWTRACE_COMPRESSION_TWO 143 bool "Compress two-level loops" 144 help 145 The trace buffer does not record loops two levels deep. Helpful if 146 the trace is spinning in a nested loop 147 148endchoice 149 150config DEBUG_BFIN_HWTRACE_COMPRESSION 151 int 152 depends on DEBUG_BFIN_HWTRACE_ON 153 default 0 if DEBUG_BFIN_HWTRACE_COMPRESSION_OFF 154 default 1 if DEBUG_BFIN_HWTRACE_COMPRESSION_ONE 155 default 2 if DEBUG_BFIN_HWTRACE_COMPRESSION_TWO 156 157 158config DEBUG_BFIN_HWTRACE_EXPAND 159 bool "Expand Trace Buffer greater than 16 entries" 160 depends on DEBUG_BFIN_HWTRACE_ON 161 default n 162 help 163 By selecting this option, every time the 16 hardware entries in 164 the Blackfin's HW Trace buffer are full, the kernel will move them 165 into a software buffer, for dumping when there is an issue. This 166 has a great impact on performance, (an interrupt every 16 change of 167 flows) and should normally be turned off, except in those nasty 168 debugging sessions 169 170config DEBUG_BFIN_HWTRACE_EXPAND_LEN 171 int "Size of Trace buffer (in power of 2k)" 172 range 0 4 173 depends on DEBUG_BFIN_HWTRACE_EXPAND 174 default 1 175 help 176 This sets the size of the software buffer that the trace information 177 is kept in. 178 0 for (2^0) 1k, or 256 entries, 179 1 for (2^1) 2k, or 512 entries, 180 2 for (2^2) 4k, or 1024 entries, 181 3 for (2^3) 8k, or 2048 entries, 182 4 for (2^4) 16k, or 4096 entries 183 184config DEBUG_BFIN_NO_KERN_HWTRACE 185 bool "Turn off hwtrace in CPLB handlers" 186 depends on DEBUG_BFIN_HWTRACE_ON 187 default y 188 help 189 The CPLB error handler contains a lot of flow changes which can 190 quickly fill up the hardware trace buffer. When debugging crashes, 191 the hardware trace may indicate that the problem lies in kernel 192 space when in reality an application is buggy. 193 194 Say Y here to disable hardware tracing in some known "jumpy" pieces 195 of code so that the trace buffer will extend further back. 196 197config EARLY_PRINTK 198 bool "Early printk" 199 default n 200 select SERIAL_CORE_CONSOLE 201 help 202 This option enables special console drivers which allow the kernel 203 to print messages very early in the bootup process. 204 205 This is useful for kernel debugging when your machine crashes very 206 early before the console code is initialized. After enabling this 207 feature, you must add "earlyprintk=serial,uart0,57600" to the 208 command line (bootargs). It is safe to say Y here in all cases, as 209 all of this lives in the init section and is thrown away after the 210 kernel boots completely. 211 212config NMI_WATCHDOG 213 bool "Enable NMI watchdog to help debugging lockup on SMP" 214 default n 215 depends on SMP 216 help 217 If any CPU in the system does not execute the period local timer 218 interrupt for more than 5 seconds, then the NMI handler dumps debug 219 information. This information can be used to debug the lockup. 220 221config CPLB_INFO 222 bool "Display the CPLB information" 223 help 224 Display the CPLB information via /proc/cplbinfo. 225 226config ACCESS_CHECK 227 bool "Check the user pointer address" 228 default y 229 help 230 Usually the pointer transfer from user space is checked to see if its 231 address is in the kernel space. 232 233 Say N here to disable that check to improve the performance. 234 235config BFIN_ISRAM_SELF_TEST 236 bool "isram boot self tests" 237 default n 238 help 239 Run some self tests of the isram driver code at boot. 240 241config BFIN_PSEUDODBG_INSNS 242 bool "Support pseudo debug instructions" 243 default n 244 help 245 This option allows the kernel to emulate some pseudo instructions which 246 allow simulator test cases to be run under Linux with no changes. 247 248 Most people should say N here. 249 250config BFIN_PM_WAKEUP_TIME_BENCH 251 bool "Display the total time for kernel to resume from power saving mode" 252 default n 253 help 254 Display the total time when kernel resumes normal from standby or 255 suspend to mem mode. 256 257endmenu 258