On Sat, 3 Sep 2011, Stefan Hajnoczi wrote: > Hi Steven, > The Xen platform PCI device has a logging feature that is currently > implemented using trace_xen_platform_log(s->log_buffer). String > arguments may not be supported by all trace backends so they should be > avoided. For example, the simple trace backend logs 8-byte arguments > and therefore cannot log strings - it will simply log the char * > pointer value, not the actual log message. Here is what > docs/tracing.txt says: > > Pointers (including char *) cannot be dereferenced easily (or at all) in > some trace backends. If pointers are used, ensure they are meaningful by > themselves and do not assume the data they point to will be traced. Do > not pass in string arguments. > > Is there a better place to send the log output?
Ideally they would go to syslog: the idea was to write a syslog trace backend but it hasn't been done yet. It seems to me that having the ability to trace a string would be very useful; we could implement a fallback tracing function to those backends that don't support char* logging natively.