boottrace: rc annotations

[mhorne]

Summary

Extend the rc framework to generate boottrace entries around the execution
of each rc script, if enabled.

[0mp]

libexec/rc/rc.subr

1446

2221

if we use command -v here we don't have to spawn an extra process I think.

[mhorne]

Handle 0mp's comments.

[0mp]

libexec/rc/rc.subr

1414–1416

Now that I think about it, a variable name starting with rc_ would fit better. e.g., rc_boottrace.

2222

Quoting is always a good idea here. Especially if one day we decide that boottrace_cmd is configurable.

[mhorne]

Handle @0mp's comments.

[0mp]

libexec/rc/rc.subr

2223

Last minor thing would be to document that this variable is available. Ideally in rc.subr(8) where rc_* variables like rc_arg and rc_flags are documented.

Also, would be nice to add boottrace(4) to either rc or rc.subr.

[mhorne]

libexec/rc/rc.subr

2223

Sure, I've made a note to do this as a follow-up.