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Mike Frysinger74ce8322007-11-21 23:50:49 +08001menu "Kernel hacking"
2
3source "lib/Kconfig.debug"
4
Robin Getza45d5752009-01-07 23:14:38 +08005config 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
Robin Getz9f06c38f2008-10-10 18:13:21 +080012config DEBUG_VERBOSE
13 bool "Verbose fault messages"
14 default y
15 select PRINTK
16 help
17 When a program crashes due to an exception, or the kernel detects
18 an internal error, the kernel can print a not so brief message
19 explaining what the problem was. This debugging information is
20 useful to developers and kernel hackers when tracking down problems,
21 but mostly meaningless to other people. This is always helpful for
22 debugging but serves no purpose on a production system.
23 Most people should say N here.
24
Mike Frysinger74ce8322007-11-21 23:50:49 +080025config DEBUG_MMRS
Mike Frysinger73ecfcf2007-09-25 05:14:15 +000026 tristate "Generate Blackfin MMR tree"
Mike Frysinger74ce8322007-11-21 23:50:49 +080027 select DEBUG_FS
28 help
29 Create a tree of Blackfin MMRs via the debugfs tree. If
30 you enable this, you will find all MMRs laid out in the
31 /sys/kernel/debug/blackfin/ directory where you can read/write
32 MMRs directly from userspace. This is obviously just a debug
33 feature.
34
35config DEBUG_HWERR
36 bool "Hardware error interrupt debugging"
37 depends on DEBUG_KERNEL
38 help
39 When enabled, the hardware error interrupt is never disabled, and
40 will happen immediately when an error condition occurs. This comes
41 at a slight cost in code size, but is necessary if you are getting
42 hardware error interrupts and need to know where they are coming
43 from.
44
Robin Getzb9a38992009-05-18 18:33:26 +000045config EXACT_HWERR
46 bool "Try to make Hardware errors exact"
47 depends on DEBUG_HWERR
48 help
49 By default, the Blackfin hardware errors are not exact - the error
50 be reported multiple cycles after the error happens. This delay
51 can cause the wrong application, or even the kernel to receive a
52 signal to be killed. If you are getting HW errors in your system,
Lucas De Marchi25985ed2011-03-30 22:57:33 -030053 try turning this on to ensure they are at least coming from the
Robin Getzb9a38992009-05-18 18:33:26 +000054 proper thread.
55
56 On production systems, it is safe (and a small optimization) to say N.
57
Robin Getz0c7a6b22008-10-08 16:27:12 +080058config DEBUG_DOUBLEFAULT
59 bool "Debug Double Faults"
60 default n
61 help
62 If an exception is caused while executing code within the exception
63 handler, the NMI handler, the reset vector, or in emulator mode,
64 a double fault occurs. On the Blackfin, this is a unrecoverable
65 event. You have two options:
66 - RESET exactly when double fault occurs. The excepting
67 instruction address is stored in RETX, where the next kernel
68 boot will print it out.
69 - Print debug message. This is much more error prone, although
70 easier to handle. It is error prone since:
71 - The excepting instruction is not committed.
72 - All writebacks from the instruction are prevented.
73 - The generated exception is not taken.
74 - The EXCAUSE field is updated with an unrecoverable event
75 The only way to check this is to see if EXCAUSE contains the
76 unrecoverable event value at every exception return. By selecting
77 this option, you are skipping over the faulting instruction, and
78 hoping things stay together enough to print out a debug message.
79
80 This does add a little kernel code, but is the only method to debug
81 double faults - if unsure say "Y"
82
83choice
84 prompt "Double Fault Failure Method"
85 default DEBUG_DOUBLEFAULT_PRINT
86 depends on DEBUG_DOUBLEFAULT
87
88config DEBUG_DOUBLEFAULT_PRINT
89 bool "Print"
90
91config DEBUG_DOUBLEFAULT_RESET
92 bool "Reset"
93
94endchoice
95
Mike Frysinger74ce8322007-11-21 23:50:49 +080096config DEBUG_HUNT_FOR_ZERO
97 bool "Catch NULL pointer reads/writes"
98 default y
99 help
100 Say Y here to catch reads/writes to anywhere in the memory range
101 from 0x0000 - 0x0FFF (the first 4k) of memory. This is useful in
102 catching common programming errors such as NULL pointer dereferences.
103
104 Misbehaving applications will be killed (generate a SEGV) while the
105 kernel will trigger a panic.
106
107 Enabling this option will take up an extra entry in CPLB table.
108 Otherwise, there is no extra overhead.
109
110config DEBUG_BFIN_HWTRACE_ON
111 bool "Turn on Blackfin's Hardware Trace"
112 default y
113 help
114 All Blackfins include a Trace Unit which stores a history of the last
115 16 changes in program flow taken by the program sequencer. The history
116 allows the user to recreate the program sequencer’s recent path. This
117 can be handy when an application dies - we print out the execution
118 path of how it got to the offending instruction.
119
120 By turning this off, you may save a tiny amount of power.
121
122choice
123 prompt "Omit loop Tracing"
124 default DEBUG_BFIN_HWTRACE_COMPRESSION_OFF
125 depends on DEBUG_BFIN_HWTRACE_ON
126 help
127 The trace buffer can be configured to omit recording of changes in
128 program flow that match either the last entry or one of the last
129 two entries. Omitting one of these entries from the record prevents
130 the trace buffer from overflowing because of any sort of loop (for, do
131 while, etc) in the program.
132
133 Because zero-overhead Hardware loops are not recorded in the trace buffer,
134 this feature can be used to prevent trace overflow from loops that
135 are nested four deep.
136
137config DEBUG_BFIN_HWTRACE_COMPRESSION_OFF
138 bool "Trace all Loops"
139 help
140 The trace buffer records all changes of flow
141
142config DEBUG_BFIN_HWTRACE_COMPRESSION_ONE
143 bool "Compress single-level loops"
144 help
145 The trace buffer does not record single loops - helpful if trace
146 is spinning on a while or do loop.
147
148config DEBUG_BFIN_HWTRACE_COMPRESSION_TWO
149 bool "Compress two-level loops"
150 help
151 The trace buffer does not record loops two levels deep. Helpful if
152 the trace is spinning in a nested loop
153
154endchoice
155
156config DEBUG_BFIN_HWTRACE_COMPRESSION
157 int
158 depends on DEBUG_BFIN_HWTRACE_ON
159 default 0 if DEBUG_BFIN_HWTRACE_COMPRESSION_OFF
160 default 1 if DEBUG_BFIN_HWTRACE_COMPRESSION_ONE
161 default 2 if DEBUG_BFIN_HWTRACE_COMPRESSION_TWO
162
163
164config DEBUG_BFIN_HWTRACE_EXPAND
165 bool "Expand Trace Buffer greater than 16 entries"
166 depends on DEBUG_BFIN_HWTRACE_ON
167 default n
168 help
169 By selecting this option, every time the 16 hardware entries in
170 the Blackfin's HW Trace buffer are full, the kernel will move them
171 into a software buffer, for dumping when there is an issue. This
172 has a great impact on performance, (an interrupt every 16 change of
173 flows) and should normally be turned off, except in those nasty
174 debugging sessions
175
176config DEBUG_BFIN_HWTRACE_EXPAND_LEN
177 int "Size of Trace buffer (in power of 2k)"
178 range 0 4
179 depends on DEBUG_BFIN_HWTRACE_EXPAND
180 default 1
181 help
182 This sets the size of the software buffer that the trace information
183 is kept in.
184 0 for (2^0) 1k, or 256 entries,
185 1 for (2^1) 2k, or 512 entries,
186 2 for (2^2) 4k, or 1024 entries,
187 3 for (2^3) 8k, or 2048 entries,
188 4 for (2^4) 16k, or 4096 entries
189
190config DEBUG_BFIN_NO_KERN_HWTRACE
Mike Frysingere60cb8a2009-01-07 23:14:38 +0800191 bool "Turn off hwtrace in CPLB handlers"
Mike Frysinger74ce8322007-11-21 23:50:49 +0800192 depends on DEBUG_BFIN_HWTRACE_ON
Mike Frysingere60cb8a2009-01-07 23:14:38 +0800193 default y
Mike Frysinger74ce8322007-11-21 23:50:49 +0800194 help
Mike Frysingere60cb8a2009-01-07 23:14:38 +0800195 The CPLB error handler contains a lot of flow changes which can
Mike Frysinger74ce8322007-11-21 23:50:49 +0800196 quickly fill up the hardware trace buffer. When debugging crashes,
197 the hardware trace may indicate that the problem lies in kernel
198 space when in reality an application is buggy.
199
200 Say Y here to disable hardware tracing in some known "jumpy" pieces
201 of code so that the trace buffer will extend further back.
202
203config EARLY_PRINTK
204 bool "Early printk"
205 default n
Sonic Zhang0cfbb322008-10-09 17:39:37 +0800206 select SERIAL_CORE_CONSOLE
Mike Frysinger74ce8322007-11-21 23:50:49 +0800207 help
208 This option enables special console drivers which allow the kernel
209 to print messages very early in the bootup process.
210
211 This is useful for kernel debugging when your machine crashes very
212 early before the console code is initialized. After enabling this
213 feature, you must add "earlyprintk=serial,uart0,57600" to the
214 command line (bootargs). It is safe to say Y here in all cases, as
215 all of this lives in the init section and is thrown away after the
216 kernel boots completely.
217
Graf Yang60ffdb32010-01-20 10:56:24 +0000218config NMI_WATCHDOG
219 bool "Enable NMI watchdog to help debugging lockup on SMP"
220 default n
Graf Yangc4298862010-03-17 09:00:32 +0000221 depends on SMP
Graf Yang60ffdb32010-01-20 10:56:24 +0000222 help
223 If any CPU in the system does not execute the period local timer
224 interrupt for more than 5 seconds, then the NMI handler dumps debug
225 information. This information can be used to debug the lockup.
226
Mike Frysinger74ce8322007-11-21 23:50:49 +0800227config CPLB_INFO
228 bool "Display the CPLB information"
229 help
Mike Frysingercf934252008-02-02 15:32:40 +0800230 Display the CPLB information via /proc/cplbinfo.
Mike Frysinger74ce8322007-11-21 23:50:49 +0800231
232config ACCESS_CHECK
233 bool "Check the user pointer address"
234 default y
235 help
236 Usually the pointer transfer from user space is checked to see if its
237 address is in the kernel space.
238
239 Say N here to disable that check to improve the performance.
240
Mike Frysingerc40cdb22009-08-27 01:46:48 +0000241config BFIN_ISRAM_SELF_TEST
242 bool "isram boot self tests"
243 default n
244 help
245 Run some self tests of the isram driver code at boot.
246
Robin Getz6ce3e9c2010-03-16 14:40:17 +0000247config BFIN_PSEUDODBG_INSNS
248 bool "Support pseudo debug instructions"
249 default n
250 help
251 This option allows the kernel to emulate some pseudo instructions which
252 allow simulator test cases to be run under Linux with no changes.
253
254 Most people should say N here.
255
Mike Frysinger74ce8322007-11-21 23:50:49 +0800256endmenu