| menu "Kernel hacking" |
| |
| source "lib/Kconfig.debug" |
| |
| config DEBUG_STACKOVERFLOW |
| bool "Check for stack overflows" |
| depends on DEBUG_KERNEL |
| help |
| This option will cause messages to be printed if free stack space |
| drops below a certain limit. |
| |
| config DEBUG_VERBOSE |
| bool "Verbose fault messages" |
| default y |
| select PRINTK |
| help |
| When a program crashes due to an exception, or the kernel detects |
| an internal error, the kernel can print a not so brief message |
| explaining what the problem was. This debugging information is |
| useful to developers and kernel hackers when tracking down problems, |
| but mostly meaningless to other people. This is always helpful for |
| debugging but serves no purpose on a production system. |
| Most people should say N here. |
| |
| config DEBUG_MMRS |
| tristate "Generate Blackfin MMR tree" |
| select DEBUG_FS |
| help |
| Create a tree of Blackfin MMRs via the debugfs tree. If |
| you enable this, you will find all MMRs laid out in the |
| /sys/kernel/debug/blackfin/ directory where you can read/write |
| MMRs directly from userspace. This is obviously just a debug |
| feature. |
| |
| config DEBUG_HWERR |
| bool "Hardware error interrupt debugging" |
| depends on DEBUG_KERNEL |
| help |
| When enabled, the hardware error interrupt is never disabled, and |
| will happen immediately when an error condition occurs. This comes |
| at a slight cost in code size, but is necessary if you are getting |
| hardware error interrupts and need to know where they are coming |
| from. |
| |
| config EXACT_HWERR |
| bool "Try to make Hardware errors exact" |
| depends on DEBUG_HWERR |
| help |
| By default, the Blackfin hardware errors are not exact - the error |
| be reported multiple cycles after the error happens. This delay |
| can cause the wrong application, or even the kernel to receive a |
| signal to be killed. If you are getting HW errors in your system, |
| try turning this on to ensure they are at least coming from the |
| proper thread. |
| |
| On production systems, it is safe (and a small optimization) to say N. |
| |
| config DEBUG_DOUBLEFAULT |
| bool "Debug Double Faults" |
| default n |
| help |
| If an exception is caused while executing code within the exception |
| handler, the NMI handler, the reset vector, or in emulator mode, |
| a double fault occurs. On the Blackfin, this is a unrecoverable |
| event. You have two options: |
| - RESET exactly when double fault occurs. The excepting |
| instruction address is stored in RETX, where the next kernel |
| boot will print it out. |
| - Print debug message. This is much more error prone, although |
| easier to handle. It is error prone since: |
| - The excepting instruction is not committed. |
| - All writebacks from the instruction are prevented. |
| - The generated exception is not taken. |
| - The EXCAUSE field is updated with an unrecoverable event |
| The only way to check this is to see if EXCAUSE contains the |
| unrecoverable event value at every exception return. By selecting |
| this option, you are skipping over the faulting instruction, and |
| hoping things stay together enough to print out a debug message. |
| |
| This does add a little kernel code, but is the only method to debug |
| double faults - if unsure say "Y" |
| |
| choice |
| prompt "Double Fault Failure Method" |
| default DEBUG_DOUBLEFAULT_PRINT |
| depends on DEBUG_DOUBLEFAULT |
| |
| config DEBUG_DOUBLEFAULT_PRINT |
| bool "Print" |
| |
| config DEBUG_DOUBLEFAULT_RESET |
| bool "Reset" |
| |
| endchoice |
| |
| config DEBUG_HUNT_FOR_ZERO |
| bool "Catch NULL pointer reads/writes" |
| default y |
| help |
| Say Y here to catch reads/writes to anywhere in the memory range |
| from 0x0000 - 0x0FFF (the first 4k) of memory. This is useful in |
| catching common programming errors such as NULL pointer dereferences. |
| |
| Misbehaving applications will be killed (generate a SEGV) while the |
| kernel will trigger a panic. |
| |
| 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 "Turn off hwtrace in CPLB handlers" |
| depends on DEBUG_BFIN_HWTRACE_ON |
| default y |
| help |
| The CPLB error handler contains a lot of flow changes which can |
| quickly fill up the hardware trace buffer. When debugging crashes, |
| the hardware trace may indicate that the problem lies in kernel |
| space when in reality an application is buggy. |
| |
| Say Y here to disable hardware tracing in some known "jumpy" pieces |
| of code so that the trace buffer will extend further back. |
| |
| config EARLY_PRINTK |
| bool "Early printk" |
| default n |
| select SERIAL_CORE_CONSOLE |
| help |
| This option enables special console drivers which allow the kernel |
| to print messages very early in the bootup process. |
| |
| This is useful for kernel debugging when your machine crashes very |
| early before the console code is initialized. After enabling this |
| feature, you must add "earlyprintk=serial,uart0,57600" to the |
| command line (bootargs). It is safe to say Y here in all cases, as |
| all of this lives in the init section and is thrown away after the |
| kernel boots completely. |
| |
| config NMI_WATCHDOG |
| bool "Enable NMI watchdog to help debugging lockup on SMP" |
| default n |
| depends on SMP |
| help |
| If any CPU in the system does not execute the period local timer |
| interrupt for more than 5 seconds, then the NMI handler dumps debug |
| information. This information can be used to debug the lockup. |
| |
| config CPLB_INFO |
| bool "Display the CPLB information" |
| help |
| Display the CPLB information via /proc/cplbinfo. |
| |
| config ACCESS_CHECK |
| bool "Check the user pointer address" |
| default y |
| help |
| Usually the pointer transfer from user space is checked to see if its |
| address is in the kernel space. |
| |
| Say N here to disable that check to improve the performance. |
| |
| config BFIN_ISRAM_SELF_TEST |
| bool "isram boot self tests" |
| default n |
| help |
| Run some self tests of the isram driver code at boot. |
| |
| config BFIN_PSEUDODBG_INSNS |
| bool "Support pseudo debug instructions" |
| default n |
| help |
| This option allows the kernel to emulate some pseudo instructions which |
| allow simulator test cases to be run under Linux with no changes. |
| |
| Most people should say N here. |
| |
| endmenu |
