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

[Rick Chen]

 > > From: Auer, Lukas [mailto:lukas.auer at aisec.fraunhofer.de]
 > > Sent: Wednesday, September 05, 2018 5:53 AM
 > > To: bmeng.cn at gmail.com
 > > Cc: Rick Jian-Zhi Chen(陳建志); u-boot at lists.denx.de
 > > Subject: Re: [U-Boot] [PATCH 12/12] riscv: Add QEMU virt board support
 > >
 > > 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.
 > >

Hi Bin and Auer

I have already boot bbl run in S-mode and riscv-linux in M-mode via
u-boot from SD card or FLASH.
It mean after booting riscv-linux, u-boot will be dead. And no matter
about kernel.
Please refer to doc/README.ae350

May I figure out more clearly what are you going to do ?
What are you going to do is let u-boot run in S-mode and boot bbl and
riscv-linux in M-mode, right ?
It mean after booting bbl and riscv-linux, u-boot will still alive and
handle SBI calls and somethings in S-mode.

Or u-boot is going to replace the role of bbl ?

Rick



 > > > > 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