AMD Family 15h [SOC|Processors]¶
Family 15h is a line of AMD x86 products first introduced in 2011. The initial microarchitecture, codenamed “Bulldozer”, introduced the concept of a “Compute Unit” (CU) where some parts of the processor are shared between two cores and some parts are unique for each core. Family 15h offerings matured into various models with increased performance and features targeting Enterprise, Client, and Embedded designs. Notice that a particular model can address more than one market(see models references below).
The first CU designs were 2 x86 cores with separate integer processors but sharing cache, code branch prediction engine and floating point processor. A die can have up to 8 CU. The floating point processor is composed of two symmetrical 128-bit FMAC. Provided each x86 core is doing 128-bit floating point arithmetic, they both do floating point simultaneously. If one is doing 256-bit floating point, the other x86 core can’t do floating point simultaneously. Later models changed how resources were shared, and introduced other performance improvements.
Family 15h products range from SOCs to 3-chip solutions. Devices designed to contain on-die graphics (including headless) are commonly referred to as APUs, not CPUs.
Later SOCs include a Platform Security Processor (PSP), a small ARM processor responsible for security related measures: For example, if secure boot is enabled, the cores will not exit reset until the BIOS image within the SPI flash is authenticated through its OEM signature, thus ensuring that only OEM produced BIOS can run the platform.
Support in coreboot for modern AMD products is based on AMD’s reference code: AMD Generic Encapsulated Software Architecture (AGESA™). AGESA contains the code for enabling DRAM, configuring proprietary core logic, assistance with generating ACPI tables, and other features.
While coreboot contains support for most models, some implementations use a separate cpu/north/south bridge directory structure. Newer products for models 60h-6Fh (Merlin Falcon) and 70h-7Fh (Stoney Ridge) rely on modern SOC directory structure.