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@@ -269,3 +269,27 @@ p0:c22:t0:spr008: 0xc0000000008a97f0 p0t: 0 1 2 3 4 5 6 7 c22: A A A A ``` + +### Hardware Trace Macro +Expoitation of HTM is limited to POWER9 NestHTM from the powerpc host. + +Using HTM requires a kernel built with both `CONFIG_PPC_MEMTRACE=y` +(v4.14) and `CONFIG_SCOM_DEBUGFS=y`. debugfs should be mounted at +`/sys/kernel/debug`. + +pdbg provides `htm_trace` which will configure the hardware and +start tracing as well as `htm_analyse` which still stop the trace and +dump the result to a file. + +``` +./pdbg -b host -d p9 -a htm_trace +[allow test to run] +./pdbg -b host -d p9 -a htm_analyse +``` +If you are running into a checkstop issue, `htm_trace` will print the +physical address of the buffer it is tracing into and the BMC can be +used to recover this memory after checkstop see `getmem`. + +pdbg also provides some of the basic functionality to use HTM, such as +`htm_reset`, `htm_start` and `htm_stop` to perform each step manually +if required. |