[U-Boot] [RESEND PATCH v2 14/15] riscv: Add QEMU virt board support

[Bin Meng]

Hi Lukas,

On Mon, Sep 17, 2018 at 5:02 AM Auer, Lukas
<lukas.auer at aisec.fraunhofer.de> wrote:
>
> Hi Bin,
>
> On Mon, 2018-09-10 at 21:54 -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.
> >
> > Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
> >
> > ---
>
> Reviewed-by: Lukas Auer <lukas.auer at aisec.fraunhofer.de>
>
> [snip]
>
> >
> > diff --git a/board/emulation/qemu-riscv/Kconfig
> > b/board/emulation/qemu-riscv/Kconfig
> > new file mode 100644
> > index 0000000..029f5efb
> > --- /dev/null
> > +++ b/board/emulation/qemu-riscv/Kconfig
> > @@ -0,0 +1,21 @@
> > +if TARGET_QEMU_VIRT
> > +
> > +config SYS_BOARD
> > +     default "qemu-riscv"
> > +
> > +config SYS_VENDOR
> > +     default "emulation"
> > +
> > +config SYS_CPU
> > +     default "qemu"
> > +
> > +config SYS_CONFIG_NAME
> > +     default "qemu-riscv"
> > +
> > +config SYS_TEXT_BASE
> > +     default 0x80000000
> > +
> > +config BOARD_SPECIFIC_OPTIONS # dummy
> > +     def_bool y
> > +
>
> Out of curiosity, what is BOARD_SPECIFIC_OPTIONS used for? I see that
> other boards have included it as well, but I don't see it actually used
> anywhere.

This option is used to select or imply some board-specific options,
mostly drivers, so that we can avoid specifying them in the board
defconfig files. I think I should have at least moved the
CONFIG_SYS_NS16550 here. I am also working on virtio drivers, and once
they are done, these drivers can be implied here too.

Regards,
Bin