Hi,
On 2024-09-17 at 07:16:46, Bagas Sanjaya (bagasdotme@gmail.com) wrote:
On Mon, Sep 16, 2024 at 04:04:37PM +0530, Linu Cherian wrote:
+3. On a kernel panic, all coresight blocks are disabled, necessary
- metadata is synced by kernel panic handler.
"... and necessary metadata ..."
- System would eventually reboot or boot a crashdump kernel.
+4. For platforms that supports crashdump kernel, raw trace data can be
- dumped using the coresight sysfs interface from the crashdump kernel
- itself. Persistent RAM is not a requirement in this case.
+5. For platforms that supports persistent RAM, trace data can be dumped
- using the coresight sysfs interface in the subsequent Linux boot.
- Crashdump kernel is not a requirement in this case. Persistent RAM
- ensures that trace data is intact across reboot.
+Coresight trace during Watchdog reset +------------------------------------- +The main difference between addressing the watchdog reset and kernel panic +case are below,
"... are:"
+Sample commands for testing a Kernel panic case with ETR sink +-------------------------------------------------------------
+1. Boot Linux kernel with "crash_kexec_post_notifiers" added to the kernel
- bootargs. This is mandatory if the user would like to read the tracedata
- from the crashdump kernel.
+2. Enable the preloaded ETM configuration
- #echo 1 > /sys/kernel/config/cs-syscfg/configurations/panicstop/enable
+3. Configure CTI using sysfs interface::
- #./cti_setup.sh
- #cat cti_setup.sh
- cd /sys/bus/coresight/devices/
- ap_cti_config () {
#ETM trig out[0] trigger to Channel 0echo 0 4 > channels/trigin_attach- }
- etf_cti_config () {
#ETF Flush in trigger from Channel 0echo 0 1 > channels/trigout_attachecho 1 > channels/trig_filter_enable- }
- etr_cti_config () {
#ETR Flush in from Channel 0echo 0 1 > channels/trigout_attachecho 1 > channels/trig_filter_enable- }
- ctidevs=`find . -name "cti*"`
- for i in $ctidevs
- do
cd $iconnection=`find . -name "ete*"`if [ ! -z "$connection" ]thenecho "AP CTI config for $i"ap_cti_configficonnection=`find . -name "tmc_etf*"`if [ ! -z "$connection" ]thenecho "ETF CTI config for $i"etf_cti_configficonnection=`find . -name "tmc_etr*"`if [ ! -z "$connection" ]thenecho "ETR CTI config for $i"etr_cti_configficd ..- done
+Note: CTI connections are SOC specific and hence the above script is +added just for reference.
+4. Choose reserved buffer mode for ETR buffer
- #echo "resrv" > /sys/bus/coresight/devices/tmc_etr0/buf_mode_preferred
+5. Enable stop on flush trigger configuration
- #echo 1 > /sys/bus/coresight/devices/tmc_etr0/stop_on_flush
+6. Start Coresight tracing on cores 1 and 2 using sysfs interface
+7. Run some application on core 1
- #taskset -c 1 dd if=/dev/urandom of=/dev/null &
+8. Invoke kernel panic on core 2
- #echo 1 > /proc/sys/kernel/panic
- #taskset -c 2 echo c > /proc/sysrq-trigger
+9. From rebooted kernel or crashdump kernel, read crashdata
- #dd if=/dev/crash_tmc_etr0 of=/trace/cstrace.bin
+10. Run opencsd decoder tools/scripts to generate the instruction trace.
Format all command lines as literal code blocks to be consistent:
---- >8 ---- diff --git a/Documentation/trace/coresight/panic.rst b/Documentation/trace/coresight/panic.rst index 3b53d91cace8fd..864f6c05b3f7af 100644 --- a/Documentation/trace/coresight/panic.rst +++ b/Documentation/trace/coresight/panic.rst @@ -113,7 +113,7 @@ Sample commands for testing a Kernel panic case with ETR sink bootargs. This is mandatory if the user would like to read the tracedata from the crashdump kernel. -2. Enable the preloaded ETM configuration +2. Enable the preloaded ETM configuration:: #echo 1 > /sys/kernel/config/cs-syscfg/configurations/panicstop/enable @@ -176,22 +176,26 @@ Sample commands for testing a Kernel panic case with ETR sink Note: CTI connections are SOC specific and hence the above script is added just for reference. -4. Choose reserved buffer mode for ETR buffer +4. Choose reserved buffer mode for ETR buffer::
- #echo "resrv" > /sys/bus/coresight/devices/tmc_etr0/buf_mode_preferred
-5. Enable stop on flush trigger configuration +5. Enable stop on flush trigger configuration::
- #echo 1 > /sys/bus/coresight/devices/tmc_etr0/stop_on_flush
6. Start Coresight tracing on cores 1 and 2 using sysfs interface -7. Run some application on core 1 +7. Run some application on core 1::
- #taskset -c 1 dd if=/dev/urandom of=/dev/null &
-8. Invoke kernel panic on core 2 +8. Invoke kernel panic on core 2::
- #echo 1 > /proc/sys/kernel/panic #taskset -c 2 echo c > /proc/sysrq-trigger
-9. From rebooted kernel or crashdump kernel, read crashdata +9. From rebooted kernel or crashdump kernel, read crashdata:: #dd if=/dev/crash_tmc_etr0 of=/trace/cstrace.bin
Ack.
Thanks.
-- An old man doll... just what I always wanted! - Clara
Linu Cherian.
-
Linu Cherian