| Message ID | 20230531142300.9114-4-sunilvl@ventanamicro.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | hw/riscv/virt: pflash improvements | expand |
On Wed, May 31, 2023 at 07:53:00PM +0530, Sunil V L wrote: > +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 .... I feel that this, while accurate, has gotten more complicated than it needs to be. We're also putting the least common scenario front and center instead of opening with the one that most people are going to be using. Below is how I suggest reworking it. What do you think? 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.
On Wed, May 31, 2023 at 09:43:39AM -0700, Andrea Bolognani wrote: > On Wed, May 31, 2023 at 07:53:00PM +0530, Sunil V L wrote: > > +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 .... > > I feel that this, while accurate, has gotten more complicated than it > needs to be. We're also putting the least common scenario front and > center instead of opening with the one that most people are going to > be using. > > Below is how I suggest reworking it. What do you think? > > > > 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. > Hi Andrea, This looks great! Thank you very much. Unless I see an objection, I will use this text in the next revision of the series tomorrow. Thanks! Sunil
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 ------------------------