Re: [libvirt] [PATCH v4] libxl: define a per-domain logger.

libxl doesn't provide a way to write one log for each domain. Thus we need to demux the messages. If our logger doesn't know to which domain to attribute a message, then it will write it to the default log file. Starting with Xen 4.9 (commit f9858025 and following), libxl will write the domain ID in an easy to grab manner. The logger introduced by this commit will use it to demux the libxl log messages. Thanks to the default log file, this logger will also work with older versions of Xen. --- * v4: delay the log file opening to the first message write.