Harvin missed his second straight practice yesterday in Eden Prairie, Minn., because of migraine headaches, a problem he’s had most of his life and that cost him one game this season. He has been invaluable to the Vikings as a wide receiver, kickoff returner, and even occasionally as a runner out of the backfield.

Coach Brad Childress called the situation “less than ideal’’ and said Harvin’s ability to fly with the team today to New Orleans could be affected. Childress also noted Harvin has played before under the same conditions.

“I have no idea what’s going to happen,’’ quarterback Brett Favre said of his trusty third-down target. “We hope he plays, but we have to prepare as we’ve been doing, like Percy’s playing.’’

Better news for the Vikings was the return to practice of starting defensive linemen Ray Edwards and Kevin Williams. They’re each listed as questionable, with knee injuries that kept them out of practice the previous two days. Edwards wore a brace on his right knee.

“We’ll see how they bounce back [today],’’ Childress said. “That’s always the litmus test.’’

Shockey, an eight-year veteran, had three catches for 36 yards and a touchdown in last week’s victory over Arizona, but hurt the knee on his 17-yard TD reception.