[U-Boot] [PATCH v2 00/11] SiFive FU540 Support

[Anup Patel]

> -----Original Message-----
> From: Bin Meng [mailto:bmeng.cn at gmail.com]
> Sent: Monday, January 21, 2019 11:44 AM
> To: Anup Patel <Anup.Patel at wdc.com>
> Cc: Atish Patra <Atish.Patra at wdc.com>; Auer, Lukas
> <lukas.auer at aisec.fraunhofer.de>; sjg at chromium.org;
> rick at andestech.com; joe.hershberger at ni.com;
> yamada.masahiro at socionext.com; paul.walmsley at sifive.com;
> palmer at sifive.com; hch at infradead.org; u-boot at lists.denx.de;
> agraf at suse.de
> Subject: Re: [PATCH v2 00/11] SiFive FU540 Support
> 
> Hi Anup,
> 
> On Mon, Jan 21, 2019 at 12:04 PM Anup Patel <Anup.Patel at wdc.com>
> wrote:
> >
> >
> >
> > > -----Original Message-----
> > > From: Atish Patra [mailto:atish.patra at wdc.com]
> > > Sent: Monday, January 21, 2019 7:07 AM
> > > To: Auer, Lukas <lukas.auer at aisec.fraunhofer.de>; sjg at chromium.org;
> > > bmeng.cn at gmail.com; rick at andestech.com; Anup Patel
> > > <Anup.Patel at wdc.com>; joe.hershberger at ni.com;
> > > yamada.masahiro at socionext.com
> > > Cc: paul.walmsley at sifive.com; palmer at sifive.com; hch at infradead.org;
> > > u- boot at lists.denx.de; agraf at suse.de
> > > Subject: Re: [PATCH v2 00/11] SiFive FU540 Support
> > >
> > > On 1/20/19 12:34 PM, Auer, Lukas wrote:
> > > > Hi Anup,
> > > >
> > > > On Fri, 2019-01-18 at 11:18 +0000, Anup Patel wrote:
> > > >> This patchset adds SiFive Freedom Unleashed (FU540) support to
> > > >> RISC-V U-Boot.
> > > >>
> > > >> The patches are based upon latest RISC-V U-Boot tree
> > > >> (git://git.denx.de/u-boot-riscv.git) at commit id
> > > >> 91882c472d8c0aef4db699d3f2de55bf43d4ae4b
> > > >>
> > > >> All drivers namely: SiFive PRCI, SiFive Serial, and Cadance MACB
> > > >> Ethernet work fine on actual SiFive Unleashed board and QEMU
> > > >> sifive_u machine.
> > > >>
> > > >
> > > > Thanks for working on this! Are you also planning on adding the
> > > > features of the FSBL to U-Boot to remove it from the boot flow?
> > > >
> > >
> > > That would also mean that adding M-mode capability in U-boot. As of
> > > now the expected boot flow is
> > >
> > > ZSBL->FSBL------->BBL/OpenSBI--------->U-boot------------->Linux
> > > (M mode from ROM)  (M mode from DRAM)  (S Mode from DRAM)  (S
> Mode
> > > from
> > > DRAM)
> > >
> > > This is not the mandated boot flow but running the last stage boot
> > > loader from S-mode gives flexibility in virtualization in future.
> >
> > To elaborate more on what Atish already mentioned, our rationale
> > behind
> > ZSBL->FSBL->BBL/OpenSBI->U-Boot(or Any other general bootloader) is
> > as follows:
> > 1. We don't want to replicate FSBL code (DRAM and other system-level
> > init) in general purpose bootloaders (U-Boot, UEFI/Tianocore, etc) 2.
> > We don't want to replicate SBI runtime implementation in general
> > purpose bootloaders (U-Boot, UEFI/Tianocore, etc) 3. We want to use
> > general purpose bootloader (U-Boot, UEFI/Tianocore, etc) inside
> > Guest/VM (S-mode)
> >
> > Of course, above boot flow is not mandatory. There could be RISC-V
> > systems where prior booting stages (such as ZSBL and FSBL) don't exist
> > so users have following options:
> > 1. Run U-Boot in M-mode for such RISC-V systems and link to OpenSBI
> > static library for SBI runtime services 2. Run U-Boot in S-mode but do
> > most system-level initialization (including DRAM init) in OpenSBI
> > firmware. In other words, use following booting flow:
> > OpenSBI (M-mode) -> U-Boot (S-mode)
> >
> > For point1 above, we will first try it with U-Boot M-mode on QEMU Virt
> > machine.
> 
> Has the OpenSBI project be started somewhere?

Yes, it exist on Github under https://github.com/riscv

Currently, OpenSBI is at-par with BBL in-terms of SBI implementation
but it is extensible and supports lot more boards/targets namely:
1. QEMU virt machine
2. QEMU sifive_u machine
3. SiFive FU540 Unleashed board
4. Kendryte K210 board

We are almost there and just need some more time for finishing
touches. We will be making is Public very soon (few more days)
so stay tuned.

Of course, we will need help from everyone to make OpenSBI
better after all it be a community driver open-source project.

There is SBI extensions spec under discussion which will be
added in OpenSBI once it is frozen.

All of us will be present at up-coming FOSDEM19 to talk about
SBI extensions, OpenSBI project, and other stuff.

Best Regards,
Anup Patel