Intel® Pentium® Silver and Intel® Celeron® Processors Datasheet, Volume 1
Multiple OOB Master
PCHs typically have multiple embedded processors such as the PMC and CSE. From an eSPI perspective, these are all classified as Out-of-Band (OOB) processors (as distinct from the Host processor). Since any such OOB processors may need to communicate with the eSPI device on the platform (e.g., EC. BMC), the eSPI controller implements dedicated OOB channel for each OOB processors including PMC and CSE to improve the interface performance and potentially enable new usage models.