ZynqMP APU RAM Start

[Chris Johns]

On 14/5/2024 4:04 pm, Sebastian Huber wrote:
> Hello,
> 
> the ZynqMP APU RAM start addresses are far away from 0x0:
> 
> cat spec/build/bsps/aarch64/xilinx-zynqmp/optramori.yml
> SPDX-License-Identifier: CC-BY-SA-4.0 OR BSD-2-Clause
> actions:
> - get-integer: null
> - assert-uint32: null
> - env-assign: null
> - format-and-define: null
> build-type: option
> copyrights:
> - Copyright (C) 2020 On-Line Applications Research (OAR)
> default:
> - enabled-by:
>   - aarch64/xilinx_zynqmp_lp64_a53
>   - aarch64/xilinx_zynqmp_ilp32_zu3eg
>   - aarch64/xilinx_zynqmp_lp64_cfc400x
>   - aarch64/xilinx_zynqmp_lp64_zu3eg
>   value: 0x10000000
> - enabled-by: true
>   value: 0x40018000
> description: |
>   base address of memory area available to the BSP
> enabled-by: true
> format: '{:#010x}'
> links: []
> name: BSP_XILINX_ZYNQMP_RAM_BASE
> type: build
> 
> What is the rationale for doing this? Any objections to change the start address
> to 0x0?
Not from me but existing workflows will break. Some things to keep in mind:

What is the default address used by Linux on this board and what uboot expects?

What do the Xilinx tools default to?

> What is the MMU page size used by the BSPs? Would it be possible to add a NULL
> pointer protection page?

I am not sure.

Chris