For debugging purposes, it would be useful if a client could output 'strace' like information about which native functions are being called, with which argument values. e.g.:

    open(".", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY|O_CLOEXEC) = 3
    fstat64(3, {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
    fcntl64(3, F_GETFD) = 0x1 (flags FD_CLOEXEC)
    getdents64(3, /* 18 entries */, 4096) = 496
    getdents64(3, /* 0 entries */, 4096) = 0
    close(3) = 0
    fstat64(1, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
    mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7f2c000
    write(1, "autofs\nbackups\ncache\nflexlm\ngames"..., 86autofsA

Jextract can help out significantly here, by generating these trace calls automatically in the bindings for downcalls and upcalls.

We could either have a --trace command line flag to emit these calls, or have a system property in the generated bindings that can be used to enable tracing.