So x? -4≥0，x+m≥0

The solution is x≥2, or x≤ -2 and x ≥-m.

When x≥2, -m≤ 2, that is, m≥ -2.

When x≤ -2, -m≤ -2 and m≥2.

So there is a solution when m≥ -2.

Therefore, there is no solution when m.