[U-Boot] [PATCH 12/12] riscv: Add QEMU virt board support

[Auer, Lukas]

On Tue, 2018-09-04 at 17:31 +0800, Bin Meng wrote:
> Hi Lukas,
> 
> On Tue, Sep 4, 2018 at 5:39 AM Auer, Lukas
> <lukas.auer at aisec.fraunhofer.de> wrote:
> > 
> > On Thu, 2018-08-30 at 00:54 -0700, Bin Meng wrote:
> > > This adds QEMU RISC-V 'virt' board target support, with the hope
> > > of
> > > helping people easily test U-Boot on RISC-V.
> > > 
> > > The QEMU virt machine models a generic RISC-V virtual machine
> > > with
> > > support for the VirtIO standard networking and block storage
> > > devices.
> > > It has CLINT, PLIC, 16550A UART devices in addition to VirtIO and
> > > it also uses device-tree to pass configuration information to
> > > guest
> > > software. It implements RISC-V privileged architecture spec
> > > v1.10.
> > > 
> > > Both 32-bit and 64-bit builds are supported. Support is pretty
> > > much
> > > preliminary, only booting to U-Boot shell with the UART driver on
> > > a single core. Booting Linux is not supported yet.
> > > 
> > 
> > For your information and to avoid duplicate work, I am working on a
> > patch set that improves RISC-V support in u-boot. I am currently
> > able
> > to boot Linux on a multi-core setup in QEMU, but they are not quite
> > ready to submit yet.
> > 
> 
> This is great! My next step is to work on virtio driver support in
> U-Boot as qemu-riscv virt machine has these devices but we don't have
> corresponding drivers in U-Boot. Then I will try to boot Linux after
> that. Good to hear you already boot Linux with qemu-riscv! Have you
> already supported virtio drivers in your port? If yes, I will just
> hold on and wait for your patch series :-)
> 

Hi Bin,

Support for the virtio devices would be great! I don't support them in
my port, I can only boot a kernel image from RAM. 
I only have a driver for the clint0 (core local interrupt controller),
which I need for software interrupts to other cores and as a timer.
Software interrupts also work over the supervisor binary interface
(SBI), which allows u-boot to run in supervisor mode with bbl running
in machine mode to handle the SBI calls.

> > Thank you for your patches, it's great to see better support for
> > RISC-V
> > in u-boot! I will add a few comments based on what I have learned
> > so
> > far from working with u-boot on RISC-V.
> > 
> 
> It's a good start. RISC-V is pretty new and needs more developers :-)
> 

Exactly :)

Thanks,
Lukas