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powerpc/powernv: Re-enable imc trace-mode in kernel 

commit <249fad734a25> ""powerpc/perf: Disable trace_imc pmu"
disables IMC(In-Memory Collection) trace-mode in kernel, since frequent
mode switching between accumulation mode and trace mode via the spr LDBAR
in the hardware can trigger a checkstop(system crash).

Patch to re-enable imc-trace mode in kernel.

The previous patch(1/2) in this series will address the mode switching issue
by implementing a global lock, and will restrict the usage of
accumulation and trace-mode at a time.

Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200313055238.8656-2-anju@linux.vnet.ibm.com
This commit is contained in:
Anju T Sudhakar 2020-03-13 11:22:38 +05:30 committed by Michael Ellerman
parent a36e8ba60b
commit 4bdd39460b
1 changed files with 1 additions and 8 deletions
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9
arch/powerpc/platforms/powernv/opal-imc.c
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@ -268,14 +268,7 @@ static int opal_imc_counters_probe(struct platform_device *pdev)
domain = IMC_DOMAIN_THREAD;
break;
case IMC_TYPE_TRACE:
/*
* FIXME. Using trace_imc events to monitor application
* or KVM thread performance can cause a checkstop
* (system crash).
* Disable it for now.
*/
pr_info_once("IMC: disabling trace_imc PMU\n");
domain = -1;
domain = IMC_DOMAIN_TRACE;
break;
default:
pr_warn("IMC Unknown Device type \n");