Re: POSIX error names and codes in PV protocols

[Oleksandr Andrushchenko <andr2000@gmail.com>]

On 01/27/2017 10:01 AM, Jan Beulich wrote:
>>>> On 26.01.17 at 18:28, <andr2000@gmail.com> wrote:
>> The problem is that it is not exposed to Linux, but I can see it
>> in FreeBSD [1] and the helper to convert error codes [2] there as well.
>> Is there any reason these are not available in Linux?
> Well, the header should eventually get added there (but see also
> Julien's reply as to why no-one may have cared so far).
>
>> Besides this fact,
>> Konrad, Stefano, are you ok that we say in the protocol file that
>> these are the error codes used?
>> As error codes are unsigned ints, what should be used in packets?
>> uint16_t or uint32_t?
> Conventionally error codes are signed ints, and the width you
> need should be mostly dictated by other structure size constraints
> (i.e. if you have ample of space, int32_t may be more efficient to
> access, but if you have space restrictions, then int16_t should be
> fine as it can represent quite a bit larger a range than error codes
> will cover in the foreseeable future).
yes, what I put in sndif now is:
/*
  * STATUS RETURN CODES.
  *
  * Status return code is zero on success and -XEN_EXX on failure.
  */
...
  * status - int32_t, response status, zero on success and -XEN_EXX on 
failure
...
> Jan
>


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