LOL! Funny, isn’t it?
Look at this: https://github.com/BPI-SINOVOIP/BPI-M3-bsp/blob/master/linux-sunxi/arch/arm/configs/sun8iw6p1smp_bpi_defconfig#L488-L489
Great, yes? At least this config they didn’t fuck up (like missing 1-Wire support for example – can you imagine you bought an SBC where you can’t use thermal sensors through 1-Wire? Simply because the vendor “forgot” to add support for 1-Wire in the kernel?).
So you could use uEnv.txt in u-boot if the u-boot version they use would use uEnvt.txt to pass kernel command line parameters. Do they use an u-boot version capable of doing that? Ask them! Most likely answer: “” (nothing as usual)
Compare the output of
with line 488 in the URL above. So, do you already get the idea how to boot from SATA? By exchanging line 488 in the kernel config and to rebuild not only the kernel but the whole BSP. BTW: You can’t boot from SATA anyway: Since the M3 has NO SATA anymore. It’s just the slowest USB-to-SATA bridge available behind an internal USB hub. Therefore you might be able to boot from USB. But keep in mind that when you try to boot and have a thumb drive plugged in everything will change since then /dev/sda might be /dev/sdb.
Isn’t that amazing? How much everything we were used to with Banana Pi M1 (where a community exists and such things like software support – also by community) differs from what we have now with M2 and M3? Because now you’re lost since you’ve to rely on your hardware manufacturer solely that doesn’t give a shit about software, useability and support. They simply rehashed stuff from Allwinner to create the impression they would also produce software suitable to be used with their hardware.
BTW: Why on earth do you post your question here in this thread? Are you really trying to use the Raspbian image from 2015-11-21?! Have you already had a look how many essential fixes you’re missing since they don’t provide a way to upgrade kernel, bootloader and hardware initialisation after release of any of their OS images? Everything here listed after 2015-11-21 you’re missing: https://github.com/BPI-SINOVOIP/BPI-M3-bsp/commits/master
Or is the OS image they link to from “20151208”? Who knows… it’s just a bunch of crap they provide here. One OS image after the other containing outdated kernel, bootloader, wrong hardware initialisation combined with any random rootfs they found somewhere else