A kernel actor is a bounded mailbox

This figure documents the historical i386 source baseline. Current native x86-64/AArch64 qualification is recorded separately; this is not an ELF64 or native SMP implementation diagram.

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A kernel actor is a bounded mailbox actor_send or a named route chooses a target using local-first or round-robin policy. Local delivery enqueues a message if capacity exists; actor_recv removes it and links its cause. The kernel has 64 actor slots, 64 messages per mailbox and a 256-byte message payload maximum. Unknown/full destinations fail; remote proxies use federation. These are not the local Hew runtime mailboxes. send->route route->local local->box yes · capacity available local->remote remote proxy local->reject unknown / full box->recv application receives send actor_send / actor_send_by_name route Actor ID / named route local-first or round-robin local Local destination? box Kernel actor mailbox head · read 64 message slots tail · write message: type + sender + ≤256 payload bytes + causal ID recv actor_recv remove message + emit receive cause remote Remote proxy → federation reject Missing / full mailbox → delivery failure note 64 actor slots · these mailboxes are kernel objects, not the cooperative Hew runtime's actor mailboxes.
A kernel actor is a bounded mailbox actor_send or a named route chooses a target using local-first or round-robin policy. Local delivery enqueues a message if capacity exists; actor_recv removes it and links its cause. The kernel has 64 actor slots, 64 messages per mailbox and a 256-byte message payload maximum. Unknown/full destinations fail; remote proxies use federation. These are not the local Hew runtime mailboxes. 64 kernel actor slots. Separate from cooperative Hew mailboxes. send->route route->local local->box yes · capacity local:e->remote:e remote local:e->fail:e unknown / full box->recv send actor_send / actor_send_by_name route Named route / actor ID local-first or round-robin local Local destination? box Kernel actor mailbox 64 slots · ≤256 payload bytes head/read → tail/write type + sender + causal ID recv actor_recv remove message; emit receive cause remote Remote proxy → federation fail Missing / full → delivery failure

Named routes choose a local mailbox or a remote proxy; neither is an unbounded queue.

Text equivalent and source references
  • actor_send or a named route chooses a target using local-first or round-robin policy. Local delivery enqueues a message if capacity exists; actor_recv removes it and links its cause.
  • The kernel has 64 actor slots, 64 messages per mailbox and a 256-byte message payload maximum. Unknown/full destinations fail; remote proxies use federation. These are not the local Hew runtime mailboxes.

Routing / ring-buffer map. Source paths refer to the atlas baseline; the kernel checkout is private.

  • include/actor.h · actor_t, actor_msg_t, actor_route_t
  • kernel/graph/actor.c · actor_send, actor_send_by_name, actor_recv

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