The cold host_bootstrap hunts the agent beacon across physical RAM and is
slow and unstable: after a restart the adapter re-scans from scratch, minutes
in which there is no address-space context to vend, though the guest is long
booted and its System DTB (kcr3) is unchanged.
Cache the kcr3 from a successful live scan in a watch-dir sibling of the slot
map (tmpfs: survives a restart, dies with the RAM file on host reboot). On
attach, re-validate the cached kcr3 against the live RAM via an O_RDONLY
context (open_ro_fd, which bypasses the beacon scan) plus a System-cr3 match,
and publish the read datum immediately when it still resolves the kernel. A
guest reboot changes the System DTB, so a stale kcr3 no longer resolves and
falls back to a cold scan: the boot-session discriminator is the kcr3 itself,
not file metadata.
The gva_write target is never taken from the cache: it is set only by a fresh
live scan, so a persisted kcr3 is a read locator only and MEMWRITE stays
fail-closed until a cold bootstrap acquires the write hold.
Persist is off unless the path is supplied (NULL keeps current behaviour).
Bump 0.3.12.
The cold address-space bootstrap (host_bootstrap -> System DTB) ran once and was
terminal: when the adapter attached before the guest finished booting, no System
process was found, the adapter emitted a single ERROR and never retried, so the
memctx datum was never published.
Make it self-healing: on bootstrap failure arm a one-shot backoff timerfd (a
second adapter fd, demuxed by cookie) that re-kicks the bootstrap until it
succeeds; reset and disarm on success. Drop the per-failure URGENT ERROR (a
still-booting guest is transient, not a fault) for a single diagnostic line on
the first failure. Add a stub fail-injection (cfg fail_boots) and test_retry.
Bump 0.3.5.
- core: runtime attach/detach of a per-endpoint adapter trio (runtime-safe add_adapter + vmsig_core_detach_endpoint, deferred reap)
- roster: VMSIG_EV_ROSTER + CAP_ROSTER, retained per-endpoint and replayed to late subscribers
- discovery: inotify trigger dir, vmid/endpoint slot allocator, host probe; vmsigd daemon with config + per-uid admission
- input driver and vgpu perception built in-tree; vgpu perception as a separate library
- memctx: own the supplied ro_fd (closed at detach)
- deb packaging: install rules, systemd unit, tmpfiles, default config
- CMD_MEMWRITE now carries a target page-table root (cr3) as its first field;
cr3 == 0 keeps the kernel address-space default (backward-compatible). A control
that has discovered a process's cr3 through its own read-only perception can
write that process's private memory under the same exclusive write lease.
Freshness of the cr3 is the control's responsibility — signaling does not
validate it (that is perception, not coherence), mirroring the read side.
- A socket control can now carry an SRC larger than the inline frame budget: a
length-prefixed SRC tail follows the CMD_MEMWRITE frame (flag SRC_PAYLOAD, the
length being the frame's own len). A per-connection two-phase receiver
accumulates the tail into a fixed conn-owned buffer up to the extent bound,
matching the in-process payload path. A zero or over-bound length is a framing
violation that closes the connection: leaving the promised tail unread would
desync the stream and draining an arbitrary length would be a denial of service.
The capability, exclusive lease, source and extent gates are unchanged and
reused; only the event header gained the cr3 field and the socket transport
gained the tail receiver. The adapter resolves cr3 == 0 to the kernel root on
its worker thread and writes atomically.
An epoll-driven, neutral transfer-event bus that connects sensors and input
actuators to one or more controls, bidirectionally. It owns the transfer context
and events — delivery order, priority, protocol-level timing, and an
interrupt-driven event model over fd sources (eventfd/timerfd/sockets) — and
stays agnostic to both the sensor/input drivers and the control.
What lives here:
- memctx: a coherent address-space context per endpoint — the guest address-space
root paired with a pre-opened read-only RAM-region fd, with per-endpoint epoch
invalidation and retained replay to late subscribers. Perception lives in
out-of-tree sensor libraries that consume this datum read-only.
- exclusive-ownership leases for destructive resource classes (input, power,
memory-write).
- write-signaled memory writes (MEMWRITE): an atomic write to guest memory routed
through the seam under an exclusive lease, never a writable mapping.
- a host-management seam for VM lifecycle/status and a neutral input-injection
command path.
- multi-VM endpoints; capability-gated, audited control authorization over an
in-process or unix-socket transport.
Builds against headers only by default (a stub mode that exercises the seam
without a VM); armed builds link the real sensor/input libraries behind flags.
lirent
