Blackfin arch: Add ability to expend the hardware trace buffer
Add ability to expend the hardware trace buffer via a configurable
software buffer - so you can have lots of history when a crash occurs.
The interesting way we do printk in the traps.c confusese the checking
script
Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index 9ce675e..a7a6e0c5 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -1024,8 +1024,89 @@
Enabling this option will take up an extra entry in CPLB table.
Otherwise, there is no extra overhead.
+config DEBUG_BFIN_HWTRACE_ON
+ bool "Turn on Blackfin's Hardware Trace"
+ default y
+ help
+ All Blackfins include a Trace Unit which stores a history of the last
+ 16 changes in program flow taken by the program sequencer. The history
+ allows the user to recreate the program sequencer’s recent path. This
+ can be handy when an application dies - we print out the execution
+ path of how it got to the offending instruction.
+
+ By turning this off, you may save a tiny amount of power.
+
+choice
+ prompt "Omit loop Tracing"
+ default DEBUG_BFIN_HWTRACE_COMPRESSION_OFF
+ depends on DEBUG_BFIN_HWTRACE_ON
+ help
+ The trace buffer can be configured to omit recording of changes in
+ program flow that match either the last entry or one of the last
+ two entries. Omitting one of these entries from the record prevents
+ the trace buffer from overflowing because of any sort of loop (for, do
+ while, etc) in the program.
+
+ Because zero-overhead Hardware loops are not recorded in the trace buffer,
+ this feature can be used to prevent trace overflow from loops that
+ are nested four deep.
+
+config DEBUG_BFIN_HWTRACE_COMPRESSION_OFF
+ bool "Trace all Loops"
+ help
+ The trace buffer records all changes of flow
+
+config DEBUG_BFIN_HWTRACE_COMPRESSION_ONE
+ bool "Compress single-level loops"
+ help
+ The trace buffer does not record single loops - helpful if trace
+ is spinning on a while or do loop.
+
+config DEBUG_BFIN_HWTRACE_COMPRESSION_TWO
+ bool "Compress two-level loops"
+ help
+ The trace buffer does not record loops two levels deep. Helpful if
+ the trace is spinning in a nested loop
+
+endchoice
+
+config DEBUG_BFIN_HWTRACE_COMPRESSION
+ int
+ depends on DEBUG_BFIN_HWTRACE_ON
+ default 0 if DEBUG_BFIN_HWTRACE_COMPRESSION_OFF
+ default 1 if DEBUG_BFIN_HWTRACE_COMPRESSION_ONE
+ default 2 if DEBUG_BFIN_HWTRACE_COMPRESSION_TWO
+
+
+config DEBUG_BFIN_HWTRACE_EXPAND
+ bool "Expand Trace Buffer greater than 16 entries"
+ depends on DEBUG_BFIN_HWTRACE_ON
+ default n
+ help
+ By selecting this option, every time the 16 hardware entries in
+ the Blackfin's HW Trace buffer are full, the kernel will move them
+ into a software buffer, for dumping when there is an issue. This
+ has a great impact on performance, (an interrupt every 16 change of
+ flows) and should normally be turned off, except in those nasty
+ debugging sessions
+
+config DEBUG_BFIN_HWTRACE_EXPAND_LEN
+ int "Size of Trace buffer (in power of 2k)"
+ range 0 4
+ depends on DEBUG_BFIN_HWTRACE_EXPAND
+ default 1
+ help
+ This sets the size of the software buffer that the trace information
+ is kept in.
+ 0 for (2^0) 1k, or 256 entries,
+ 1 for (2^1) 2k, or 512 entries,
+ 2 for (2^2) 4k, or 1024 entries,
+ 3 for (2^3) 8k, or 2048 entries,
+ 4 for (2^4) 16k, or 4096 entries
+
config DEBUG_BFIN_NO_KERN_HWTRACE
bool "Trace user apps (turn off hwtrace in kernel)"
+ depends on DEBUG_BFIN_HWTRACE_ON
default n
help
Some pieces of the kernel contain a lot of flow changes which can