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

From: Alistair Francis
Subject: [Qemu-riscv] [RFC v1 0/5] RISC-V: Add firmware loading support and default
Date: Tue, 18 Jun 2019 17:38:44 -0700

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
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, 
  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
 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


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