There’s a very interesting part of the gem5 Coding Style document, talking about different message status from M5. I consider them very useful for further work.
M5 Message Status
By their purpose, M5 message functions are divided into two parts: the error functions and the alert functions.
Error functions
There are two error functions defined in src/base/misc.hh, panic() and
fatal(). They have roughly similar behaviors but differ in purposes and use
case. Here’s the description given by the gem5 document.
panic()should be called when something happens that should never ever happen regardless of what the user does (i.e., an actual m5 bug).fatal()should be called when the simulation cannot continue due to some condition that is the user’s fault (bad configuration, invalid arguments, etc.) and not a simulator bug.
Alert functions
gem5 provides 3 functions as choices to alert its user: inform(), warn()
and hack().
inform()should be called for informative messages that users should know, but not worry about.warn()should be called when some functionality isn’t necessarily implemented correctly, but it might work well enough. The idea behind ahack()should be called when some functionality isn’t implemented nearly as well as it could or should be but for expediency or history sake hasn’t been fixed.
Acknoledgements
Most of the contents are from gem5’s Coding Style part documentation. Please refer to this site for more detailed informations.