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PORTFEATURES(9) FreeBSD Kernel Developer's Manual PORTFEATURES(9) NAME portfeatures - the __HAVEs (and the have nots) DESCRIPTION Machine-independent kernel code adapts to differences in hardware capabilities provided by the machine-dependent parts of the kernel. A port declares its capabilities by defining various __HAVE_feature macros. This manual page provides an index of such macros with pointers to other manual pages in the kernel section that provide all the relevant details. __HAVE_MUTEX_STUBS (mutex(9)) The port provides fast path mutex enter and exit stubs. __HAVE_PREEMPTION (cpu_need_resched(9)) The port can preempt kernel lwps with RESCHED_KPREEMPT. __HAVE_PTRACE_MACHDEP The port has MD ptrace(2) requests, defines PTRACE_MACHDEP_REQUEST_CASES macro with case labels for its MD requests. __HAVE_RAS (ras(9)) The port supports restartable atomic sequences. __HAVE_SIMPLE_MUTEXES (mutex(9)) The port provides a CAS function that is either MP-safe, or does not need to be MP safe. Adaptive mutexes on these architectures do not require an additional interlock. __HAVE_SPIN_MUTEX_STUBS (mutex(9)) The port provides fast path enter and exit stubs for spin mutexes. __HAVE_UCAS_FULL (ucas(9)) The port provides a full implementation of the low-level primitives required for atomic compare-and-swap operations to user-space addresses. __HAVE_UCAS_MP (ucas(9)) The port does not provide a full implementation of the low- level primitives required for atomic compare-and-swap operations to user-space addresses, but does provide an implementation of those primitives that can be used if (and only if) the system has more than one processor. FreeBSD 14.1-RELEASE-p8 March 6, 2023 FreeBSD 14.1-RELEASE-p8