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 <suni...@ventanamicro.com> Reviewed-by: Philippe Mathieu-Daudé <phi...@linaro.org> --- docs/system/riscv/virt.rst | 43 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) diff --git a/docs/system/riscv/virt.rst b/docs/system/riscv/virt.rst index 4b16e41d7f..6c1d4fed3e 100644 --- a/docs/system/riscv/virt.rst +++ b/docs/system/riscv/virt.rst @@ -53,6 +53,49 @@ 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 +------------------- + +When KVM is not enabled, the first flash device (pflash0) can contain either +the 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. + +When KVM is enabled, pflash0 is always assumed to contain the S-mode payload +firmware. + +Firmware images used for pflash should be of size 32 MiB. + +To boot as ROM code: + +.. code-block:: bash + + $ qemu-system-riscv64 -bios none \ + -blockdev node-name=pflash0,driver=file,read-only=on,filename=<rom_code> \ + -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> \ + -blockdev node-name=pflash1,driver=file,filename=<s-mode_fw_vars> \ + -M virt,pflash0=pflash0,pflash1=pflash1 \ + ... other args .... + +To boot as read-only S-mode payload in KVM guest: + +.. code-block:: bash + + $ qemu-system-riscv64 \ + -blockdev node-name=pflash0,driver=file,read-only=on,filename=<s-mode_fw_code> \ + -blockdev node-name=pflash1,driver=file,filename=<s-mode_fw_vars> \ + -M virt,pflash0=pflash0,pflash1=pflash1 \ + --enable-kvm \ + ... other args .... + Machine-specific options ------------------------ -- 2.34.1
