Does Biot-Savart law apply in magnetic materials or only in vacuum?

[hazal]

Homework Statement

Or is it only valid in vacuum condition? Segment of straight wire carrying current I
(at distance r)
dB = u.Idl x r / 4pi . r^2

(I've came across it on a book about Maxwell's Equations.)

Homework Equations

The Attempt at a Solution

Does correction have to be made for polarization or magnetization of the material medium? If so, how?

 

[DrDu]

In a medium, I would expect it to hold with dH instead of dB.