Re: [Qemu-devel] [PATCH] Allow default network type to be determined from an environmental variable

[Paul Brook]

> I think Paul Brook was concerned about a situation where a user
> reports a problem saying FOO is not working when running "qemu -hda ..."
> and suddenly the number of things that may have triggered the bug has
> grown by the size of the environment.  Even if you manage to tell the
> user to pastebin the environment, it may have changed by then.  I'm
> pretty sure Paul knows how to list the env variables :)

Indeed. I see many, many users complain that qemu dies because of SDL errors.  
Almost without fail this is because they're running qemu in a different 
environment (e.g. under su as root), so are using an environment that can't 
connect to their X server.

Running "set | grep QEMU" is fine, except that it has to be done in the same 
environment as qemu runs in. You'd be surprised how many users are incapable 
of doing what seems to be a straightforward task.

This is similar to why I dislike qemu automagically guessing settings. If you 
force everything to be explicitly specified (or use fixed defaults) then 
there's no margin for error. If behaviour depends on external factors then 
you can guarantee the person stuck between you (the "expert") and the 
misbehaving application will have no clue how to determine or control those 
external factors.

Paul