Re: [PATCH v2 9/9] docs/system/arm: xlnx-versal-virt: BBRAM and eFUSE Usage

[Peter Maydell]

On Mon, 23 Aug 2021 at 18:49, Tong Ho <tong.ho@xilinx.com> wrote:
>
> Add BBRAM and eFUSE usage to the Xilinx Versal Virt board
> document.
>
> Signed-off-by: Tong Ho <tong.ho@xilinx.com>
> ---
>  docs/system/arm/xlnx-versal-virt.rst | 49 ++++++++++++++++++++++++++++
>  1 file changed, 49 insertions(+)
>
> diff --git a/docs/system/arm/xlnx-versal-virt.rst 
> b/docs/system/arm/xlnx-versal-virt.rst
> index 27f73500d9..84afac3734 100644
> --- a/docs/system/arm/xlnx-versal-virt.rst
> +++ b/docs/system/arm/xlnx-versal-virt.rst
> @@ -32,6 +32,8 @@ Implemented devices:
>  - OCM (256KB of On Chip Memory)
>  - XRAM (4MB of on chip Accelerator RAM)
>  - DDR memory
> +- BBRAM (36 bytes of Battery-backed RAM)
> +- eFUSE (3072 bytes of one-time field-programmable bit array)
>
>  QEMU does not yet model any other devices, including the PL and the AI 
> Engine.
>
> @@ -175,3 +177,50 @@ Run the following at the U-Boot prompt:
>    fdt set /chosen/dom0 reg <0x00000000 0x40000000 0x0 0x03100000>
>    booti 30000000 - 20000000
>
> +BBRAM File Backend
> +""""""""""""""""""
> +BBRAM can have an optional file backend, which must a seekable

"must be"

> +binary file with a size of 36 bytes or larger. A file with all
> +binary 0s is a 'blank'.
> +
> +To add a file-backend for the BBRAM:
> +
> +.. code-block:: bash
> +
> +  -drive if=pflash,index=0,file=versal-bbram.bin,format=raw
> +
> +To use a different index value, N, from default of 0, add:
> +
> +.. code-block:: bash
> +
> +  -global xlnx,bbram-ctrl.drive-index=N
> +
> +eFUSE File Backend
> +""""""""""""""""""
> +eFUSE can have an optional file backend, which must a seekable

"must be"

> +binary file with a size of 3072 bytes or larger. A file with all
> +binary 0s is a 'blank'.
> +
> +To add a file-backend for the eFUSE:
> +
> +.. code-block:: bash
> +
> +  -drive if=pflash,index=1,file=versal-efuse.bin,format=raw
> +
> +To use a different index value, N, from default of 1, add:
> +
> +.. code-block:: bash
> +
> +  -global xlnx,efuse.drive-index=N
> +
> +.. warning::
> +  In actual physical Versal, BBRAM and eFUSE contain sensitive data.
> +  The QEMU device models do **not** encrypt nor obfuscate any data
> +  when holding them in models' memory or when writing them to their
> +  file backends.
> +
> +  Thus, a file backend should be used with caution, and 'format=luks'
> +  is highly recommended (albeit with usage complexity).
> +
> +  Better yet, do not use actual product data when running guest image
> +  on this Xilinx Versal Virt board.                      |

Stray '|' at the end of the line.

-- PMM