Posted this to wrong list initially, sorry all!
I've just re-installed debian (stretch) on the Gigabyte MP30-AR0 board using the installer netinst iso (any later install images fail) and the sdcard slot is not showing up. The kernel is vmlinuz-4.9.0-11-arm64 and I have also rebuilt it ensuring all the MMC options I should need are selected.I'm now suspecting a devicetree issue. Checking the output from dtc, using 'dtc -I fs -O dts /sys/firmware/devicetree/base' there is no mention of mmc. However, an 'mmc' entry exists in the source code file 'apm-storm.dtsi', which is 'included' by 'apm-mustang.dts', which I'm assuming is the dts file used by the kernel build system, I used bindeb-pkg to build the debs.
Previously, I've manually built the image, modules and dtb (last occasion using mainline 4.9.2) and the card slot was not a problem.
Anybody any ideas as to what's happening? Can I ensure that 'bindeb-pkg' uses a specific dts? If so, how?This system dual boots with RedSleeve and that side is not a problem.