Talk:L4Re error handling

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  • interresting files ./l4sys/include/err.h, ./l4util/include/assert.h, ./l4re/include/error_helper, ./l4sys/lib/src/errtostr.c, ./cxx/lib/util/src/, ./cxx/lib/base/include/exceptions, ./cxx/lib/base/include/std_exc_io, ./moe/server/src/, ./moe/server/src/exception.h, many files containing "debug", ./l4sys/include/ARCH-*/kdebug.h
  • BD: JDB, the kernel debugger, could be relevant in so far that you could mention enter_kdebug().
    • usage: enter_kdebug("some message which helps others to find this call and see some state");
    • enters jdb, prints this message
    • NO jdb documentation at this time and place (BD: do you mean there's no documentation available? The basics in are still valid.)
  • common types which can represent error conditions: l4_cap_idx_t, Cap, l4_msgtag_t
  • l4_cap_idx_t and Cap are very similar, cause Cap is a wrapper for l4_cap_idx_t
    • can be invalid
    • check l4_cap_idx_t with l4_is_invalid_cap and l4_is_valid_cap
    • check Cap with L4::Cap_base::is_valid
    • TODO where and when do we use L4::Cap_base::validate?
    • how to handle? log! also: don't support the feature which needs access to this capability... generally this means end the task
  • l4_msgtag_t
    • some error conditions
    • many methods to check for more or less specific errors
    • TODO talk to someone, grep code
    • Message Tag l4_msgtag_has_error and more
    • Error handling l4_ipc_error, l4_error and more specific ones, most specific seams to be l4_ipc_error_code
    • how to handle: log! depends on specific error. often task configuration error, so end task or don't provide feature

  • C++ Exceptions
    • chksys for l4_msgtag_t and long
    • chkcap for Cap<T>
    • throw some L4::Base_exception
    • has a method returning a "human readable" string! L4::Base_exception::str
    • exceptions can be printed with std::ostream
    • you can put try { } catch(e) { std::cerr << e } in your thread functions like main
    • useful usage seen in mag/server/src/

  • ./l4sys/lib/src/errtostr.c
    • l4sys_errtostr(long) for L4_E* and L4_IPC_* constants
  • ./cxx/lib/util/src/
    • TODO too funny
  • TODO grep for usage