gdb: FreeBSD
21.1.7 FreeBSD
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When the ABI of a system call is changed in the FreeBSD kernel, this is
implemented by leaving a compatibility system call using the old ABI at
the existing number and allocating a new system call number for the
version using the new ABI. As a convenience, when a system call is
caught by name (catch syscall), compatibility system calls are
also caught.
For example, FreeBSD 12 introduced a new variant of the 'kevent'
system call and catching the 'kevent' system call by name catches both
variants:
(gdb) catch syscall kevent
Catchpoint 1 (syscalls 'freebsd11_kevent' [363] 'kevent' [560])
(gdb)