Novell spinners said that Mantel's departure would not impact its Linux strategy, but it must lend some weight to those who fear that the company is losing the plot a bit over SuSE.
In May, former SuSE president Richard Seibt cleared his desk at Novell too.
Novell spokesman Bruce Lowry confirmed Mantel had quit, but also refused to elaborate.
"As a matter of policy, we don't comment on decisions by individual employees to depart the company," he said. But "we don't anticipate that this will have a negative impact on either our [Linux development] strategy or our ability to execute on that strategy."