Re: [PATCH 0/3] Add OpenSBI dynamic firmware support

[Atish Patra]

On Thu, Jun 18, 2020 at 1:56 AM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> On Wed, Jun 17, 2020 at 3:29 AM Atish Patra <atish.patra@wdc.com> wrote:
> >
> > This series adds support OpenSBI dynamic firmware support to Qemu.
> > Qemu loader passes the information about the DT and next stage (i.e. kernel
> > or U-boot) via "a2" register. It allows the user to build bigger OS images
> > without worrying about overwriting DT. It also unifies the reset vector code
>
> I am not sure in what situation overwriting DT could happen. Could you
> please elaborate?
>

Currently, the DT is loaded 0x82200000 (34MB offset) for fw_jump.
Thus, a bigger kernel image
would overwrite the DT. In fact, it was reported by FreeBSD folks.
https://github.com/riscv/opensbi/issues/169

There are temporary solutions that can put DT a little bit further or
put it within 2MB offset. But that's
just delaying the inevitable.

> > in rom and dt placement. Now, the DT is copied directly in DRAM instead of 
> > ROM.
> >
> > The changes have been verified on following qemu machines.
> >
> > 64bit:
> >  - spike, sifive_u, virt
> > 32bit:
> >  - virt
>
> Any test instructions?
>

you just need to provide fw_dynamic instead of fw_jump in bios argument.

For example: Here is my qemu commandline for testing

qemu-system-riscv64 -M virt -smp 4 -m 2g -display none -serial
mon:stdio -bios
~/workspace/opensbi/build/platform/generic/firmware/fw_dynamic.bin \
   -kernel /home/atish/workspace/linux/arch/riscv/boot/Image -initrd
/home/atish/workspace/rootfs_images/riscv64_busybox_rootfs.img -object
rng-random,filename=/dev/urandom,id=rng0 \
   -device virtio-rng-device,rng=rng0 -device
virtio-net-device,netdev=usernet -netdev
user,id=usernet,hostfwd=tcp::10000-:22 -d in_asm -D log -append 'rw
console=ttyS0 earlycon'

> >
> > I have also verified fw_jump on all the above platforms to ensure that this
> > series doesn't break the existing setup.
> >
>
> Regards,
> Bin
>


-- 
Regards,
Atish