printf in boot image app

How to get printf to appear on console
when app is executed from the boot image?
Tried including Dev.ansi but that didn’t work.

Boot image:
$ boot -v

$ Proc32 -l 1

$ Slib32

$ Dev32

$ Dev32.ser -b115200 -t8 -F 3f8,4 2f8,3

$ Dev32.ser -t8 -b57600 -Ncom 280,10 288,10 290,10 298,10

$ my-app

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