On 07/02/18 19:35, Icenowy Zheng wrote:
Allwinner 64-bit SoCs can use 4GiB DRAM chip, however their memory map has only allocated 3GiB for DRAM, so only 3GiB of the DRAM is accessible.
Add a Kconfig option for the maximum accessible DRAM.
That looks fine to me, but have you checked CONFIG_MAX_MEM_MAPPED? get_effective_memsize() in common/memsize.c looks like it's solving this very problem.
For A80 it should be a much higher value (8GiB), but as I have no A80 device to test and originally U-Boot only supports 2GiB DRAM on A80, it currently still falls under the 2GiB situation.
Well, that depends on how we will use SUNXI_DRAM_SIZE. If that's to limit the size we eventually report in the DT, that should be indeed 8GB on the A80. But U-Boot itself can't use more than 3GB on sunxi/ARMv7 (due to the static 1:1 mapping). I think we should separate those two numbers (actual DRAM size and U-Boot's own DRAM size), if we really want to support >3GB on the A80.
But maybe we should not get carried away by something that doesn't really exist.
Thanks, Andre.
Signed-off-by: Icenowy Zheng icenowy@aosc.io
arch/arm/mach-sunxi/Kconfig | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/arch/arm/mach-sunxi/Kconfig b/arch/arm/mach-sunxi/Kconfig index 1fededd0a3..32739e0f33 100644 --- a/arch/arm/mach-sunxi/Kconfig +++ b/arch/arm/mach-sunxi/Kconfig @@ -63,6 +63,13 @@ config MACH_SUNXI_H3_H5 select SUNXI_GEN_SUN6I select SUPPORT_SPL
+# TODO: try out A80's 8GiB DRAM space +config SUNXI_DRAM_MAX_SIZE
- hex
- default 0xC0000000 if MACH_SUN50I
- default 0xC0000000 if MACH_SUN50I_H5
- default 0x80000000
choice prompt "Sunxi SoC Variant" optional