Re: [Qemu-devel] [PATCH for-4.1 2/2] target/riscv: Add support for -bios "firmware_filename" flag

[Alistair Francis]

On Sat, May 18, 2019 at 2:57 PM Jonathan Behrens <address@hidden> wrote:
>
> > I've never been fully convinced of this, why not just use the generic 
> > loader?
>
> If I understand you are proposing passing bbl (or other firmware) with the 
> -kernel flag, and then vmlinux (or another kernel) with the -initrd flag? 
> Wouldn't this result in losing the ability to pass a real init ramdisk to 
> Linux? It also seems to open the possibility for strange bugs/compatibility 
> issues later if firmware starts recognizing any "initrd" entries in the 
> device tree as kernel code to jump into.

No I mean passing in OpenSBI (or some other boot loader) via the
-kernel option and then passing in the kernel with QEMU's generic
device loader. This is documented as part of the OpenSBI boot flow:
https://github.com/riscv/opensbi/blob/master/docs/platform/qemu_virt.md

The only disadvantage with that is that we don't get debug symbols
from the kernel, but it does mean that the boot loader in QEMU is much
simpler.

>
> I do wonder though how compatible the current design is with providing 
> default firmware for riscv in the future.
>
> > This should be in a generic boot.c file and support added to all RISC-V 
> > boards.
>
> I can do this for v2.

Thanks

Alistair

>
> Jonathan