Re: [Qemu-riscv] [Qemu-devel] [RFC v1 0/5] RISC-V: Add firmware loading support and default

[Bin Meng]

On Wed, Jun 19, 2019 at 8:56 AM Alistair Francis
<address@hidden> wrote:
>
> This is an RFC as it will break ALL current users! See below for details.
>
> This series consolidates the current RISC-V kernel loading
> impelementation while also adding support for the -bios option and more
> advanced kernel image types.
>
> After consolidating the kernel loading we can extend the boot loader to
> support a -bios option. We can also extend the kernel loading options to
> support not just ELF files but other standard formats.
>
> Finally we can include the OpenSBI firmware by default for QEMU users.
>
> At the end of this series we are in the good place of no longer
> requiring users to build firmware to boot a kernel. Instead users can
> just run QEMu with the -kernel option and everything will work. They can

This is great. I like booting kernel directly for testing without
bothering the firmware stuff.

> also override the firmware with their own using the -bios option. Using
> "-bios none" will result in no firmware being loaded (as it is today).
>
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>
> Unfortunately this series (patch 5 specifically) results in all current
> Linux boots being broken as users are already loading in their own
> firmware, which overlaps with the now included default. They will
> see this error:
>
>   rom: requested regions overlap (rom phdr #0: 
> ./images/qemuriscv64/fw_jump.elf. free=0x0000000080008090, 
> addr=0x0000000080000000)
>   qemu-system-riscv64: rom check and register reset failed
>
> If a current user specieifies "-bios none" their flow will continue
> working. A user can instead no longer load their firmware and
> use the default or they can load their firmware with the -bios option.
>
> At the moment the best idea I have to not break all users is to only
> include the default firmware if the user specifies "-bios opensbi".
> That is change the default to not loading the firmware. Then we can work
> on updating documentation and maybe in future change the default to
> include a firmware and anyone who doesn't want a default firmware can
> specify "-bios none".
>
> Any other ideas on how to not break everything?
>
>
>
> Alistair Francis (5):
>   hw/riscv: Split out the boot functions
>   hw/riscv: Add support for loading a firmware
>   hw/riscv: Extend the kernel loading support
>   roms: Add OpenSBI version 0.3
>   hw/riscv: Load OpenSBI as the default firmware
>
>  .gitmodules                         |   3 +
>  Makefile                            |   3 +-
>  configure                           |   1 +
>  hw/riscv/Makefile.objs              |   1 +
>  hw/riscv/boot.c                     | 143 ++++++++++++++++++++++++++++
>  hw/riscv/sifive_e.c                 |  17 +---
>  hw/riscv/sifive_u.c                 |  19 +---
>  hw/riscv/spike.c                    |  21 +---
>  hw/riscv/virt.c                     |  54 ++---------
>  include/hw/riscv/boot.h             |  30 ++++++
>  pc-bios/opensbi-riscv32-fw_jump.elf | Bin 0 -> 197988 bytes
>  pc-bios/opensbi-riscv64-fw_jump.elf | Bin 0 -> 200192 bytes

Since we are considering adding "bios" images, I prefer to add the
pure binary images instead of ELF images here.

>  roms/Makefile                       |  17 ++++
>  roms/opensbi                        |   1 +
>  14 files changed, 216 insertions(+), 94 deletions(-)
>  create mode 100644 hw/riscv/boot.c
>  create mode 100644 include/hw/riscv/boot.h
>  create mode 100644 pc-bios/opensbi-riscv32-fw_jump.elf
>  create mode 100644 pc-bios/opensbi-riscv64-fw_jump.elf
>  create mode 160000 roms/opensbi

Regards,
Bin