no sound by "Intel 6321ESB HD Audio"

i install openbsd 6.2 into mac pro 2006 .
(boot by fedora's grub )

but i cannot hear sound .

$ dmesg | grep audio
audio0 at azalia0

$ dmesg | grep azalia
azalia0 at pci0 dev 27 function 0 "Intel 6321ESB HD Audio" rev 0x09: msi
azalia0: codecs: Realtek ALC885
audio0 at azalia0

are there any advices ?
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regards