[Skiboot] [PATCH v2] hw/imc: pause microcode at boot

[Stewart Smith]

Madhavan Srinivasan <maddy at linux.vnet.ibm.com> writes:
> IMC nest counters has both in-band (ucode access) and out of
> band access to it. Since not all nest counter configurations
> are supported by ucode, out of band tools are used to characterize
> other configuration.
>
> So it is prefer to pause the nest microcode at boot to aid the
> nest out of band tools. If the ucode not paused and OS does not
> have IMC driver support, then out to band tools will race with
> ucode and end up getting undesirable values. Patch to check and
> pause the ucode at boot.
>
> OPAL provides APIs to control IMC counters. OPAL_IMC_COUNTERS_INIT
> is used to initialize these counters at boot. OPAL_IMC_COUNTERS_START
> and OPAL_IMC_COUNTERS_STOP API calls should be used to start and pause
> these IMC engines. `doc/opal-api/opal-imc-counters.rst` details the
> OPAL APIs and their usage.
>
> Signed-off-by: Madhavan Srinivasan <maddy at linux.vnet.ibm.com>
> ---
>  hw/imc.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)

Merged to master as of 9750eee802f8d6396147ee4e046e1859949a0e55

-- 
Stewart Smith
OPAL Architect, IBM.