On Tue, Sep 24, 2019 at 2:32 AM Philippe Mathieu-Daudé <phi...@redhat.com> wrote: > > On 9/23/19 11:46 PM, Peter Maydell wrote: > > On Fri, 20 Sep 2019 at 23:23, Alistair Francis <alistai...@gmail.com> wrote: > >> On Thu, Sep 19, 2019 at 10:15 PM Bin Meng <bmeng...@gmail.com> wrote: > >>> I don't think we should mirror what is used on ARM virt board to > >>> create 2 flash for sifive_u. For ARM virt, there are 2 flashes because > >>> they need distinguish secure and non-secure. For sifive_u, only one is > >>> enough. > >> > >> I went back and forward about 1 or 2. Two seems more usable as maybe > >> someone wants to include two pflash files? The Xilinx machine also has > >> two so I'm kind of used to 2, but I'm not really fussed. > > The Xilinx machine has 2 because it matches the hardware. > > > One of the reasons for having 2 on the Arm board (we do this > > even if we're not supporting secure vs non-secure) is that > > then you can use one for a fixed read-only BIOS image (backed > > by a file on the host filesystem shared between all VMs), and > > one backed by a read-write per-VM file providing permanent > > storage for BIOS environment variables. Notably UEFI likes to > > work this way, but the idea applies in theory to other > > boot loader or BIOSes I guess. > > IIRC Laszlo's explanation, the only reason it is that way is because the > pflash_cfi01 model still doesn't implement sector locking. At the OVMF > emerged from EDK2, to have a safe ROM vs DATA storage it was decided to > use 2 different flashes. > When I understood when this config layout started, I suggested Laszlo to > use a real ROM to store the OVMF CODE since it is pointless to do > firmware upgrade in virtualized environment, but he said it was too late > to change the design. > > If you don't plan to run UEFI "Capsule Update" on your Virt board, I > suggest using memory_region_init_rom() with your firmware CODE, and a > parallel/SPI flash for the data VARStore.
We might run that one day, who knows :) Alistair > > > I would suggest also checking with Markus that your code > > for instantiating the flash devices follows the current > > recommendations so the backing storage can be configured > > via -blockdev. (This is a fairly recent change from June or > > so; current-in-master virt and sbsa boards provide an example > > of doing the right thing, I think.) > > > > thanks > > -- PMM > >