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authorNicholas Piggin2021-11-23 19:51:50 +1000
committerMichael Ellerman2021-11-24 21:08:57 +1100
commit0a4b4327ce867e3ac1b3ad15f4d2b686b516b3a2 (patch)
tree5862cf843d3d5613ac58bbbd28d7acb57523823a /Documentation/admin-guide
parent245ebf8e7380b3d84c0aac37fbfd9306b45a3a7a (diff)
powerpc/64s: Implement PMU override command line option
It can be useful in simulators (with very constrained environments) to allow some PMCs to run from boot so they can be sampled directly by a test harness, rather than having to run perf. A previous change freezes counters at boot by default, so provide a boot time option to un-freeze (plus a bit more flexibility). Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Athira Jajeev <atrajeev@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211123095231.1036501-13-npiggin@gmail.com
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt8
1 files changed, 8 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 9725c546a0d4..2711ddb4835a 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4144,6 +4144,14 @@
Override pmtimer IOPort with a hex value.
e.g. pmtmr=0x508
+ pmu_override= [PPC] Override the PMU.
+ This option takes over the PMU facility, so it is no
+ longer usable by perf. Setting this option starts the
+ PMU counters by setting MMCR0 to 0 (the FC bit is
+ cleared). If a number is given, then MMCR1 is set to
+ that number, otherwise (e.g., 'pmu_override=on'), MMCR1
+ remains 0.
+
pm_debug_messages [SUSPEND,KNL]
Enable suspend/resume debug messages during boot up.