tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 EXACT_HWERR
58 bool "Try to make Hardware errors exact"
59 depends on DEBUG_HWERR
60 help
61 By default, the Blackfin hardware errors are not exact - the error
62 be reported multiple cycles after the error happens. This delay
63 can cause the wrong application, or even the kernel to receive a
64 signal to be killed. If you are getting HW errors in your system,
65 try turning this on to ensure they are at least comming from the
66 proper thread.
67
68 On production systems, it is safe (and a small optimization) to say N.
69
70config DEBUG_DOUBLEFAULT
71 bool "Debug Double Faults"
72 default n
73 help
74 If an exception is caused while executing code within the exception
75 handler, the NMI handler, the reset vector, or in emulator mode,
76 a double fault occurs. On the Blackfin, this is a unrecoverable
77 event. You have two options:
78 - RESET exactly when double fault occurs. The excepting
79 instruction address is stored in RETX, where the next kernel
80 boot will print it out.
81 - Print debug message. This is much more error prone, although
82 easier to handle. It is error prone since:
83 - The excepting instruction is not committed.
84 - All writebacks from the instruction are prevented.
85 - The generated exception is not taken.
86 - The EXCAUSE field is updated with an unrecoverable event
87 The only way to check this is to see if EXCAUSE contains the
88 unrecoverable event value at every exception return. By selecting
89 this option, you are skipping over the faulting instruction, and
90 hoping things stay together enough to print out a debug message.
91
92 This does add a little kernel code, but is the only method to debug
93 double faults - if unsure say "Y"
94
95choice
96 prompt "Double Fault Failure Method"
97 default DEBUG_DOUBLEFAULT_PRINT
98 depends on DEBUG_DOUBLEFAULT
99
100config DEBUG_DOUBLEFAULT_PRINT
101 bool "Print"
102
103config DEBUG_DOUBLEFAULT_RESET
104 bool "Reset"
105
106endchoice
107
108config DEBUG_ICACHE_CHECK
109 bool "Check Instruction cache coherency"
110 depends on DEBUG_KERNEL
111 depends on DEBUG_HWERR
112 help
113 Say Y here if you are getting weird unexplained errors. This will
114 ensure that icache is what SDRAM says it should be by doing a
115 byte wise comparison between SDRAM and instruction cache. This
116 also relocates the irq_panic() function to L1 memory, (which is
117 un-cached).
118
119config DEBUG_HUNT_FOR_ZERO
120 bool "Catch NULL pointer reads/writes"
121 default y
122 help
123 Say Y here to catch reads/writes to anywhere in the memory range
124 from 0x0000 - 0x0FFF (the first 4k) of memory. This is useful in
125 catching common programming errors such as NULL pointer dereferences.
126
127 Misbehaving applications will be killed (generate a SEGV) while the
128 kernel will trigger a panic.
129
130 Enabling this option will take up an extra entry in CPLB table.
131 Otherwise, there is no extra overhead.
132
133config DEBUG_BFIN_HWTRACE_ON
134 bool "Turn on Blackfin's Hardware Trace"
135 default y
136 help
137 All Blackfins include a Trace Unit which stores a history of the last
138 16 changes in program flow taken by the program sequencer. The history
139 allows the user to recreate the program sequencer’s recent path. This
140 can be handy when an application dies - we print out the execution
141 path of how it got to the offending instruction.
142
143 By turning this off, you may save a tiny amount of power.
144
145choice
146 prompt "Omit loop Tracing"
147 default DEBUG_BFIN_HWTRACE_COMPRESSION_OFF
148 depends on DEBUG_BFIN_HWTRACE_ON
149 help
150 The trace buffer can be configured to omit recording of changes in
151 program flow that match either the last entry or one of the last
152 two entries. Omitting one of these entries from the record prevents
153 the trace buffer from overflowing because of any sort of loop (for, do
154 while, etc) in the program.
155
156 Because zero-overhead Hardware loops are not recorded in the trace buffer,
157 this feature can be used to prevent trace overflow from loops that
158 are nested four deep.
159
160config DEBUG_BFIN_HWTRACE_COMPRESSION_OFF
161 bool "Trace all Loops"
162 help
163 The trace buffer records all changes of flow
164
165config DEBUG_BFIN_HWTRACE_COMPRESSION_ONE
166 bool "Compress single-level loops"
167 help
168 The trace buffer does not record single loops - helpful if trace
169 is spinning on a while or do loop.
170
171config DEBUG_BFIN_HWTRACE_COMPRESSION_TWO
172 bool "Compress two-level loops"
173 help
174 The trace buffer does not record loops two levels deep. Helpful if
175 the trace is spinning in a nested loop
176
177endchoice
178
179config DEBUG_BFIN_HWTRACE_COMPRESSION
180 int
181 depends on DEBUG_BFIN_HWTRACE_ON
182 default 0 if DEBUG_BFIN_HWTRACE_COMPRESSION_OFF
183 default 1 if DEBUG_BFIN_HWTRACE_COMPRESSION_ONE
184 default 2 if DEBUG_BFIN_HWTRACE_COMPRESSION_TWO
185
186
187config DEBUG_BFIN_HWTRACE_EXPAND
188 bool "Expand Trace Buffer greater than 16 entries"
189 depends on DEBUG_BFIN_HWTRACE_ON
190 default n
191 help
192 By selecting this option, every time the 16 hardware entries in
193 the Blackfin's HW Trace buffer are full, the kernel will move them
194 into a software buffer, for dumping when there is an issue. This
195 has a great impact on performance, (an interrupt every 16 change of
196 flows) and should normally be turned off, except in those nasty
197 debugging sessions
198
199config DEBUG_BFIN_HWTRACE_EXPAND_LEN
200 int "Size of Trace buffer (in power of 2k)"
201 range 0 4
202 depends on DEBUG_BFIN_HWTRACE_EXPAND
203 default 1
204 help
205 This sets the size of the software buffer that the trace information
206 is kept in.
207 0 for (2^0) 1k, or 256 entries,
208 1 for (2^1) 2k, or 512 entries,
209 2 for (2^2) 4k, or 1024 entries,
210 3 for (2^3) 8k, or 2048 entries,
211 4 for (2^4) 16k, or 4096 entries
212
213config DEBUG_BFIN_NO_KERN_HWTRACE
214 bool "Turn off hwtrace in CPLB handlers"
215 depends on DEBUG_BFIN_HWTRACE_ON
216 default y
217 help
218 The CPLB error handler contains a lot of flow changes which can
219 quickly fill up the hardware trace buffer. When debugging crashes,
220 the hardware trace may indicate that the problem lies in kernel
221 space when in reality an application is buggy.
222
223 Say Y here to disable hardware tracing in some known "jumpy" pieces
224 of code so that the trace buffer will extend further back.
225
226config EARLY_PRINTK
227 bool "Early printk"
228 default n
229 select SERIAL_CORE_CONSOLE
230 help
231 This option enables special console drivers which allow the kernel
232 to print messages very early in the bootup process.
233
234 This is useful for kernel debugging when your machine crashes very
235 early before the console code is initialized. After enabling this
236 feature, you must add "earlyprintk=serial,uart0,57600" to the
237 command line (bootargs). It is safe to say Y here in all cases, as
238 all of this lives in the init section and is thrown away after the
239 kernel boots completely.
240
241config CPLB_INFO
242 bool "Display the CPLB information"
243 help
244 Display the CPLB information via /proc/cplbinfo.
245
246config ACCESS_CHECK
247 bool "Check the user pointer address"
248 default y
249 help
250 Usually the pointer transfer from user space is checked to see if its
251 address is in the kernel space.
252
253 Say N here to disable that check to improve the performance.
254
255config BFIN_ISRAM_SELF_TEST
256 bool "isram boot self tests"
257 default n
258 help
259 Run some self tests of the isram driver code at boot.
260
261endmenu