MobileGL/docs/Disaggregated/guide/glossary.md

Terms

Reference. For the documentation index see ../README.md.

Term	Meaning
frontend / backend	frontend = MG_State + MG_Impl, handling the application's GL calls; backend = MG_Backend, calling the driver for real
Espryt / Magma	The two backends: Espryt goes through OpenGL ES (DirectGLES), Magma through Vulkan (DirectVulkan)
client / server	The frontend role / backend role after the split; they can be two threads, two processes or two machines
monolith / inproc / spawn	The three topologies: single thread direct calls / two threads in one process / two processes (optionally across machines)
pull / push	The backend reads the frontend's state itself (the old way) / the frontend pushes state to the backend (MGPipe)
verb	A command that makes the backend actually do work: draw, dispatch, clear, blit, readback, XFB, query, texture operations. State is pushed only before a verb
handle {slot, gen}	An object's identity: a client-allocated slot plus the reuse generation; the server never sends it back
CSO	Constant state object (render state, vertex format, sampler, sampler view, shader): the client deduplicates by content, the server caches by handle
control plane / data plane	The connection carrying the handshake and rare control messages / the channel carrying command records and bulk data; each can choose shared memory or a byte stream, local or TCP
lockstep / run-ahead	The client waits for the server after every command / the client sends and moves on, waiting only for commands that need an answer
barrier tax	The extra per-thread CPU cost of splitting into two threads (split − push)
device-lost	The state the client enters after the server crashes or disconnects: GL calls become no-ops and swap buffers returns "context lost" instead of crashing or hanging
class A / B / C	Slots in the backend function table: A answers locally, B becomes a record, C is not migrated yet and is refused by name
Track V / Track H	Migration of value-class read points (a whole block crosses the wire) / migration of object-class read points (object pointers become handles)
G1 / G2 / G5 / G14	Verification gates: single-process build binary byte-identical / pull and push have the same test-name set / protected backend functions byte-identical / test names only grow
red-once (R-16)	Every gate must really have run red once, proving it can fail for the problem it is meant to catch
MGGen	The server's private "I rebuilt the driver object" epoch; it never crosses the wire and is kept strictly separate from the handle generation