How would I suppress all warnings (or at least as many as possible since those prefixed with MSB cannot be suppressed How to suppress specific MSBuild warning)?
If you would like to suppress MSB3270 only then you can set in project file just
<PropertyGroup>
<ResolveAssemblyWarnOrErrorOnTargetArchitectureMismatch>
None
</ResolveAssemblyWarnOrErrorOnTargetArchitectureMismatch>
</PropertyGroup>
Missing XML comment for publicly visible type or member
/clp:ErrorsOnly to the Default parameters
msbuild /clp:ErrorsOnly
/consoleloggerparameters:
Parameters to console logger. (Short form: /clp)
The available parameters are:
PerformanceSummary--Show time spent in tasks, targets
and projects.
Summary--Show error and warning summary at the end.
NoSummary--Don't show error and warning summary at the
end.
**ErrorsOnly--Show only errors.**
WarningsOnly--Show only warnings.
NoItemAndPropertyList--Don't show list of items and
properties at the start of each project build.
ShowCommandLine--Show TaskCommandLineEvent messages
ShowTimestamp--Display the Timestamp as a prefix to any
message.
ShowEventId--Show eventId for started events, finished
events, and messages
ForceNoAlign--Does not align the text to the size of
the console buffer
DisableMPLogging-- Disable the multiprocessor
logging style of output when running in
non-multiprocessor mode.
EnableMPLogging--Enable the multiprocessor logging
style even when running in non-multiprocessor
mode. This logging style is on by default.
Verbosity--overrides the /verbosity setting for this
logger.
The best way is to fix the issues that are causing the warnings.
If you must ignore the warnings (e.g. you have inherited a project with so many that you can't see the wood for the trees), you could try changing the WarningLevel property, http://msdn.microsoft.com/en-us/library/13b90fz7.aspx