[U-Boot] [PATCH v4 1/3] net: designware: fix descriptor layout and warnings on 64-bit archs

[Beniamino Galvani <b.galvani@gmail.com>]

On Mon, Apr 18, 2016 at 01:06:37PM +0200, Alexander Graf wrote:
> Hmm, this is going to get very interesting with efi_loader support. By
> default we allocate memory at the highest possible free address, so payloads
> will probably (unless they specify limits) have their buffers above 32bit on
> this platform. If we now deny any DMA to them, we basically break I/O
> access.

I'm not familiar with efi_loader, but on this platform the physical
RAM is within the 32bit memory range, so I don't think a workaround is
needed. And I guess probably it's the same for the other 64bit ARM SoC
using this driver.

BTW, I see that another driver (sunxi_mmc) also truncates the upper 32
bits of addresses on 64bit platforms. Maybe this issue should be
addresses in a generic way?

> Could you by any chance just use a bounce buffer?

Do you have any suggestions on how to do it? Are there any primitives
in u-boot to request memory from low addresses?

Beniamino