Hi,
On 06/12/16 11:28, Maxime Ripard wrote:
On Mon, Dec 05, 2016 at 01:52:30AM +0000, Andre Przywara wrote:
When compiling the SPL for the Allwinner A64 in AArch64 mode, we can't use the more compact Thumb2 encoding, which only exists for AArch32 code. This makes the SPL rather big, up to a point where any code additions or even a different compiler may easily exceed the 32KB limit that the Allwinner BROM imposes. Introduce a separate, mostly generic sun50i-a64 configuration, which defines the CPU_V7 symbol and thus will create a 32-bit binary using the memory-saving Thumb2 encoding.
"mostly generic". Where do you draw the line? How do you deal with a board that would use a different UART? a different MMC? different memory configuration.?
My impression was that it's rather pointless to provide another set of 32-bit SPL defconfigs for each board again, especially given that for the SPL's needs the boards so far seem to be very similar. For the loading part we will probably go with what the BROM already started: load more data from one of the BROM boot sources, which is fixed in the SoC and can't be really changed by a board vendor anyway. Which really leaves the DRAM setup and the UART. I can't predict the future, but so far those A64 boards look fairly similar in this respect. So I just avoid having another SPL defconfig for the BananaPi M64, for instance. I just added MMC_SUNXI_SLOT_EXTRA because this doesn't hurt on the Pine64, so less churn here.
So if you know of any board which breaks this assumption, I am happy to hear about it and see if it can be integrated.
Actually I had the idea of eventually going the other way around: Providing one U-Boot proper A64 defconfig and let the DT (provided by the SPL) sort out the differences. Then we might be able to live with separate SPL defconfigs. But that's another patchset and probably quite some work.
This looks like it's not generic at all, it's just a configuration for the Pine64.
And the BananaPi M64. And the upcoming Olimex board (trusting their latest published schematics). If in need, we can always provide separate defconfigs for "odd" boards.
So this is the best solution I came up with, if you have a better one: I am all ears. Would it make sense to rename this file to not claim universal coverage?
Cheers, Andre.