Module dma_hint

Calculate DMA hint value if not provided by host.

Constants

LOOKUP_TABLE_DEBUG 🔒

DEV/TEST ONLY variant of the lookup table above. Since the IGVM manifest specifies additional VTL2 memory for dev (well above what is required for release configs), allow the heuristics to still kick in.

LOOKUP_TABLE_RELEASE 🔒

Lookup table for VTL2 DMA hint calculation. This table is used to retrofit dedicated DMA memory for existing configurations known at the time of writing. Dedicated DMA memory is required for devices that survive OpenHCL servicing operations (for example, NVMe and MANA devices). Those devices express their need as the “persistent memory” requirement when they create a DMA client. Since the amount of dedicated DMA memory cannot be changed at runtime, the amount of memory set aside must account for the maximum expected usage.

MAX_DMA_HINT_MEM_SIZE 🔒

Maximum allowed memory size for DMA hint calculation (1 TiB).

ONE_MB 🔒

PAGES_PER_2MB 🔒

Number of 4K pages in 2MiB.

RATIO 🔒

Functions

pick_private_pool_size

round_up_to_2mb 🔒

Round up to next 2MiB.

vtl2_calculate_dma_hint

Returns calculated DMA hint value, in 4k pages.