What boards would you consider "better" and for what reasons (gpu and crypto extensions, or are there other factors)? I run a few raspberry pis and always looking for new/better toys.
https://www.hardkernel.com/shop/odroid-n2-with-4gbyte-ram-2/
There are plenty of things that an RK3399 (or the new Rockchip being used in the OP) can handle just fine.
I was definitely interested to see that this new chip supports up to 8GB of RAM. I think there are a lot of interesting applications for RAM-rich, Gig-E bearing nodes that can run off a battery. (Examples: Redis at the edge, “Field” PostgreSQL replicated to the cloud when possible, nested VMs protecting trusted “firmware” from remotely-loaded containers and machine images, etc.)
Among other things, this means the PCIe aperture is squeezed down to a very measly 2×16MB — which is not even remotely enough for a lot of PCIe cards.
Also, if you install 4GB RAM, you only get to use something like 3.5G.
Oh and if I remember correctly, PCI MSI are broken, which again limits the PCIe card selection even more...
http://opensource.rock-chips.com/images/e/ee/Rockchip_RK3399...
Page 13 ("1.1 Address Mapping") - same thing, everything crammed into 32bit.
PCIe Aperture is documented in TRM Part 2:
https://www.t-firefly.com/download/Firefly-RK3399/docs/TRM/R...
Page 711 - and I misremembered, it's 64MB total in 1×32MB + 32×1MB blocks. For comparison, my 6 year old server has 64GB PCI aperture space on each of its 2 sockets, my Laptop has 16GB. (Obviously both >32bit address spaces... which the RK3399 really should be too, but isn't.)
MSI is blacklisted in the Linux kernel somewhere if I remember correctly; it just randomly loses interrupts.
P.S.: Address space doesn't need to make a 32->64bit jump, my laptop CPU has 39bit, my server has 46bit; even 36bit (like old Intel 32bit PAE) would've been sufficient on the RK3399. But 32bit isn't.
P.P.S.: the PCI aperture size is the most obviously a problem when you try to plug in a GPU. E.g.:
0c:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Baffin [Radeon RX 550 640SP / RX 560/560X] [1002:67ff] (rev cf) (prog-if 00 [VGA controller])
...
Region 0: Memory at 900000000 (64-bit, prefetchable) [size=4G]
Region 2: Memory at 880000000 (64-bit, prefetchable) [size=2M]
Region 4: I/O ports at f000 [size=256]
Region 5: Memory at f7e00000 (32-bit, non-prefetchable) [size=256K]
...
Capabilities: [200 v1] Physical Resizable BAR
BAR 0: current size: 4GB, supported: 256MB 512MB 1GB 2GB 4GB
The real problem is that PCI address space is not normally a scarce resource, and some RAID controllers & network cards (particularly high-performance/server ones) use a random bunch of it (>= 128MB) , and that's not even starting on SR-IOV. And these requirements aren't well documented because PCI memory space is not normally a problem. If you're lucky you can google "<card name> lspci", if not you only notice after you bought the card...