Hi Andrea, On Wed, May 24, 2023 at 03:50:34PM +0000, Andrea Bolognani wrote: > On Tue, May 23, 2023 at 03:58:05PM +0530, Sunil V L wrote: > > Currently, virt machine supports two pflash instances each with > > 32MB size. However, the first pflash is always assumed to > > contain M-mode firmware and reset vector is set to this if > > enabled. Hence, for S-mode payloads like EDK2, only one pflash > > instance is available for use. This means both code and NV variables > > of EDK2 will need to use the same pflash. > > > > The OS distros keep the EDK2 FW code as readonly. When non-volatile > > variables also need to share the same pflash, it is not possible > > to keep it as readonly since variables need write access. > > > > To resolve this issue, the code and NV variables need to be separated. > > But in that case we need an extra flash. Hence, modify the convention > > such that pflash0 will contain the M-mode FW only when "-bios none" > > option is used. Otherwise, pflash0 will contain the S-mode payload FW. > > This enables both pflash instances available for EDK2 use. > > > > Example usage: > > 1) pflash0 containing M-mode FW > > qemu-system-riscv64 -bios none -pflash <mmode_fw> -machine virt > > or > > qemu-system-riscv64 -bios none \ > > -drive file=<mmode_fw>,if=pflash,format=raw,unit=0 -machine virt > > > > 2) pflash0 containing S-mode payload like EDK2 > > qemu-system-riscv64 -pflash <smode_fw_code> -pflash <smode_vars> -machine > > virt > > or > > qemu-system-riscv64 -bios <opensbi_fw> \ > > -pflash <smode_fw_code> \ > > -pflash <smode_vars> \ > > -machine virt > > or > > qemu-system-riscv64 -bios <opensbi_fw> \ > > -drive file=<smode_fw_code>,if=pflash,format=raw,unit=0,readonly=on \ > > -drive file=<smode_fw_vars>,if=pflash,format=raw,unit=1 \ > > -machine virt > > I wanted to test this, both directly with QEMU and through libvirt,
Thank you very much for helping with this! > but I'm hitting two roadblocks. > > First off, the only RISC-V edk2 build readily accessible to me (from > the edk2-riscv64 Fedora package) is configured to work off a R/W > pflash1. You said that you have edk2 patches making R/O CODE pflash0 > and R/W VARS pflash1 ready. Any chance you could make either the > build output, or the patches and some hints on how to build edk2 > after applying them, somewhere? > Please build EDK2 using the branch https://github.com/vlsunil/edk2/tree/separate_code_vars. The instructions to build is in https://github.com/vlsunil/riscv-uefi-edk2-docs/wiki/RISC-V-Qemu-Virt-support#build-edk2 However, now it will create two images for code and vars. > Going further and testing libvirt integration. After hacking around > other issues, I finally stumbled upon this error: > > qemu-system-riscv64: Property 'virt-machine.pflash0' not found > > This is because a few years back libvirt has stopped using -drive > if=pflash for configuring pflash devices, and these days it generates > something along the lines of > > -blockdev > '{"driver":"file","filename":"...","node-name":"libvirt-pflash0-storage","auto-read-only":true,"discard":"unmap"}' > -blockdev > '{"node-name":"libvirt-pflash0-format","read-only":true,"driver":"raw","file":"libvirt-pflash0-storage"}' > -machine virt,pflash0=libvirt-pflash0-format > > instead, which both aarch64/virt and x86_64/q35 machine types are > perfectly happy with. > > I've tried to patch hw/riscv/virt.c to get the above working, and > almost managed to succeed :) but eventually my unfamiliarity with the > internals of QEMU caught up with me. Can you please look into making > this work? > Thanks!. This needs some investigation. Let me look into supporting this. Thanks! Sunil
