Re: [PATCH v4 3/3] docs/system: riscv: Add pflash usage details

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 25/5/23 18:48, Sunil V L wrote:
> pflash devices can be used in virt machine for different
> purposes like for ROM code or S-mode FW payload. Add a
> section in the documentation on how to use pflash devices
> for different purposes.
> 
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> ---
>   docs/system/riscv/virt.rst | 29 +++++++++++++++++++++++++++++
>   1 file changed, 29 insertions(+)
> 
> diff --git a/docs/system/riscv/virt.rst b/docs/system/riscv/virt.rst
> index 4b16e41d7f..c3e0b7a9c3 100644
> --- a/docs/system/riscv/virt.rst
> +++ b/docs/system/riscv/virt.rst
> @@ -53,6 +53,35 @@ with the default OpenSBI firmware image as the -bios. It also supports
>   the recommended RISC-V bootflow: U-Boot SPL (M-mode) loads OpenSBI fw_dynamic
>   firmware and U-Boot proper (S-mode), using the standard -bios functionality.
>   
> +Using flash devices
> +-------------------
> +
> +The first flash device (pflash0) can contain either ROM code
> +or S-mode payload firmware code. If the pflash0 contains the
> +ROM code, -bios should be set to none. If -bios is not set to
> +none, pflash0 is assumed to contain S-mode payload code.
> +
> +Firmware images used for pflash should be of size 32 MiB.
> +
> +To boot as ROM code:

If "ROM" ...

> +
> +.. code-block:: bash
> +
> +  $ qemu-system-riscv64 -bios none \
> +     -blockdev node-name=pflash0,driver=file,filename=<rom_code> \

... shouldn't we also enforce 'read-only=on,' ...

> +     -M virt,pflash0=pflash0 \
> +     ... other args ....
> +
> +To boot as read-only S-mode payload:
> +
> +.. code-block:: bash
> +
> +  $ qemu-system-riscv64 \
> +     -blockdev node-name=pflash0,driver=file,read-only=on,filename=<s-mode_fw_code> \

... like in S-mode?

> +     -blockdev node-name=pflash1,driver=file,filename=<s-mode_fw_vars> \
> +     -M virt,pflash0=pflash0,pflash1=pflash1 \
> +     ... other args ....
> +
>   Machine-specific options
>   ------------------------
>