Jan Kiszka wrote: > Marcelo Tosatti wrote: >> On Tue, Sep 01, 2009 at 12:44:08PM +0300, Avi Kivity wrote: >>> Instead of saving the debug registers from the processor to a kvm data >>> structure, rely in the debug registers stored in the thread structure. >>> This allows us not to save dr6 and dr7. >>> >>> Reduces lightweight vmexit cost by 350 cycles, or 11 percent. >> Is this kgdb safe? > > Nope, kgdb writes directly to the debug registers. > > I vaguely recall someone trying to push a debug register management > framework. Did it hit mainline in the meantime? I do not find any trace > on quick glance, at least not in kgdb. For the time being, falling back to conservative save/restore if kgdb is configured in and kgdb_connected != 0 should allow us to apply this optimization otherwise. Jan -- Siemens AG, Corporate Technology, CT SE 2 Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
