On Thu, Jun 1, 2023 at 3:01 PM Sunil V L <sunilvl@ventanamicro.com> 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>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Alistair
> ---
> docs/system/riscv/virt.rst | 31 +++++++++++++++++++++++++++++++
> 1 file changed, 31 insertions(+)
>
> diff --git a/docs/system/riscv/virt.rst b/docs/system/riscv/virt.rst
> index 4b16e41d7f..b33f45e5b3 100644
> --- a/docs/system/riscv/virt.rst
> +++ b/docs/system/riscv/virt.rst
> @@ -53,6 +53,37 @@ 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
> +-------------------
> +
> +By default, the first flash device (pflash0) is expected to contain
> +S-mode firmware code. It can be configured as read-only, with the
> +second flash device (pflash1) available to store configuration data.
> +
> +For example, booting edk2 looks like
> +
> +.. code-block:: bash
> +
> + $ qemu-system-riscv64 \
> + -blockdev node-name=pflash0,driver=file,read-only=on,filename=<edk2_code> \
> + -blockdev node-name=pflash1,driver=file,filename=<edk2_vars> \
> + -M virt,pflash0=pflash0,pflash1=pflash1 \
> + ... other args ....
> +
> +For TCG guests only, it is also possible to boot M-mode firmware from
> +the first flash device (pflash0) by additionally passing ``-bios
> +none``, as in
> +
> +.. code-block:: bash
> +
> + $ qemu-system-riscv64 \
> + -bios none \
> + -blockdev node-name=pflash0,driver=file,read-only=on,filename=<m_mode_code> \
> + -M virt,pflash0=pflash0 \
> + ... other args ....
> +
> +Firmware images used for pflash must be exactly 32 MiB in size.
> +
> Machine-specific options
> ------------------------
>
> --
> 2.34.1
>
>