OPAL_SLW_SET_REG

#define OPAL_SLW_SET_REG                     100

int64_t opal_slw_set_reg(uint64_t cpu_pir, uint64_t sprn, uint64_t val);

OPAL_SLW_SET_REG is used to inform low-level firmware to restore a given value of SPR when there is a state loss. The actual set of SPRs that are supported is platform dependent.

In Power 8, it uses p8_pore_gen_cpufreq_fixed(), api provided by pore engine, to inform the spr with their corresponding values with which they must be restored.

In Power 9, it uses p9_stop_save_cpureg(), api provided by self restore code, to inform the spr with their corresponding values with which they must be restored.

Parameters

uint64_t cpu_pir
This parameter specifies the pir of the cpu for which the call is being made.
uint64_t sprn
This parameter specifies the spr number as mentioned in p9_stop_api.H for Power9 and p8_pore_table_gen_api.H for Power8.
uint64_t val
This parameter specifices value with which the spr should be restored.

Returns

OPAL_INTERNAL_ERROR
On failure. The actual error code from the platform specific code is logged in the OPAL logs
OPAL_UNSUPPORTED
If spr restore is not supported by pore engine.
OPAL_SUCCESS
On success