Board-level Linux integration, U-Boot, device trees, kernel drivers and peripheral bring-up. Separate power and hardware checks from software adaptation, and define a recoverable boot path.
A cgroup memory event identifies an enforcement event, not an application defect. Diagnose a slow or restarted embedded service by aligning its cgroup counter changes, memory composition, pressure measurements, and supervisor decisions on one timeline. Then test whether the workload exceeds an intentional budget, grows without bound, or suffers pressure imposed elsewhere. Those explanations can…
A 64-bit time_t is a necessary interface choice for many long-lived 32-bit Linux applications, but it is not an end-to-end Y2038 qualification. A saved record, driver interface, protocol field or older helper process can still narrow the timestamp. Follow a future date through every conversion and prove that the same instant survives a complete round…
Set PR_SET_PDEATHSIG in the helper, then verify that its parent is still the expected supervisor captured before fork. The identity check catches a supervisor that died before the helper armed the notification; the armed signal covers a later death. This closes a missed-notification startup window, but it does not make every helper operation atomic with…
Electing the creator of a POSIX shared-memory object does not mean the object is ready for another process to use. A successful exclusive shm_open can publish a name while its length is still zero and its synchronization objects are uninitialized. Separate creation, sizing, initialization and readiness publication, and require attachers to pass each boundary before…
When pthread_mutex_lock returns EOWNERDEAD for a robust mutex, the caller has acquired the lock and must reconcile the protected data before declaring it consistent. Calling pthread_mutex_consistent is an acknowledgment of completed repair, not the repair itself. If the invariant cannot be restored, keep ordinary consumers out and follow an explicit unrecoverable-state policy. This guide uses…
Qualify POSIX message queues through the actual mq API, effective limits and IPC namespace before blaming a missing /dev/mqueue directory. The filesystem mount is an inspection view; it is not the queue’s API name. A service also needs a lifecycle for persistent queue names, compatible attributes and cleanup after failed startup. This guide uses Linux…
Read back SO_RCVBUF and SO_SNDBUF after setting them, then qualify the real traffic path. On Linux the requested value can be capped, is doubled for internal accounting and is subject to a minimum. A successful setsockopt call therefore does not prove that the requested payload capacity was installed or that the receiver can survive the…
At EMFILE, stop admitting work that needs new descriptors and preserve diagnostics through resources already open. Identify whether the exhausted resource is the process’s descriptor table, the system-wide open-file pool or another allocation path before changing limits. A larger descriptor limit can postpone a leak while leaving the same failure mechanism intact. This guide uses…
Qualify large-file support at every boundary that carries a file offset or size, including library interfaces and intermediate arithmetic. On a 32-bit glibc build, selecting _FILE_OFFSET_BITS=64 can widen the relevant interfaces, but it cannot repair an already compiled narrow library or an application field that still truncates the value to int. This guide uses Linux…
After IN_Q_OVERFLOW, treat the affected inotify instance’s incremental view as incomplete and rebuild it from authoritative filesystem state. Continuing to apply later events cannot reconstruct the missing changes. A configuration service should enter a visible reconciliation state, repair its watches and validate a complete candidate configuration before publishing a new in-memory generation. This guide follows…