Vector TCM (VTCM) is available on supported targets with cDSP. VTCM is a high-performance, tightly-coupled memory in the cDSP subsystem that can be used for Hexagon Vector eXtensions (HVX) scatter/gather instructions, Hexagon Matrix eXtension (HMX)(available in some cDSPs starting with Lahaina), or as high-performance scratch memory for other HVX workloads.

The VTCM manager exposes APIs in from the HAP_vtcm_mgr.h file to allocate, free, and query the availability of VTCM.

NOTE: Starting with Lahaina, use the compute resource manager{target=_blank} API for VTCM allocations instead of this legacy VTCM manager API. The compute resource manager is expanded to provide user options to do the following:

Allocate other compute resources (including VTCM)
Manage application IDs, which control VTCM partitions and privileges
Send release callbacks, which can be invoked when a high priority client requires the resource
Release and reacquire the same VTCM size and page configuration
Request VTCM with granular sizes (minimum and maximum required) and specific page size requirements

The VTCM manager API is restricted to allocate VTCM only from the primary VTCM partition (if the partition is defined).