Re: Testing the recent RISC-V DT patchsets

[Atish Patra]

On 5/29/19 3:04 AM, Loys Ollivier wrote:
> On Wed 29 May 2019 at 00:50, Atish Patra <atish.patra@xxxxxxx> wrote:
>
> > On 5/28/19 8:36 AM, Karsten Merker wrote:
> > > On Tue, May 28, 2019 at 05:10:42PM +0200, Loys Ollivier wrote:
> > > > On Tue 28 May 2019 at 01:32, Paul Walmsley <paul.walmsley@xxxxxxxxxx> wrote:
> > > >
> > > > > An update for those testing RISC-V patches: here's a new branch of
> > > > > riscv-pk/bbl that doesn't try to read or modify the DT data at all, which
> > > > > should be useful until U-Boot settles down.
> > > [...]
> > > > > Here is an Linux kernel branch with updated DT data that can be booted
> > > > > with the above bootloader:
> > > > >
> > > > >      https://github.com/sifive/riscv-linux/tree/dev/paulw/dts-v5.2-rc1-experimental
> > > > >
> > > > > A sample boot log follows, using a 'defconfig' build from that branch.
> > > >
> > > > Thanks Paul, I can confirm that it works.
> > > >
> > > > Something is still unclear to myself.
> > > > Using FSBL + riscv-pk/bbl the linux kernel + device tree boots.
> > > > Neither FSBL nor riscv-pk/bbl are modifying the DT.
> > > >
> > > > Using FSBL + OpenSBI + U-Boot the same kernel + device tree hangs on
> > > > running /init.
> > > >
> > > > Would you have any pointer on what riscv-pk does that OpenSBI/U-boot doesn't ?
> > > > Or maybe it is the other way around - OpenSBI/U-boot does something that
> > > > extra that should not happen.
> > >
> > > Hello,
> > >
> > > I don't know which version of OpenSBI you are using, but there is
> > > a problem with the combination of kernel 5.2-rc1 and OpenSBI
> > > versions before commit
> > >
> > >     https://github.com/riscv/opensbi/commit/4e2cd478208531c47343290f15b577d40c82649c
> > >
> > > that can result in a hang on executing init, so in case you
> > > should be using an older OpenSBI build that might be the source
> > > of the problem that you are experiencing.
> > >
> > > Regards,
> > > Karsten
> >
> > I verified the updated DT with upstream kernel for the boot flow OpenSBI
> > + U-Boot + Linux or OpenSBI + Linux.
> >
> > OpenSBI should be compiled for sifive platform with following additional
> > argument
> >
> > FW_PAYLOAD_FDT_PATH=<linux kernel
> > source>/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dtb
> >
> > FYI: It will only work when kernel is given a payload to U-Boot/OpenSBI
> > directly.
>
> Hum, I am surprised by this statement.

That's because U-Boot also using the new DT. With FW_PAYLOAD_FDT_PATH, 
OpenSBI ignores the DT from FSBL and U-Boot gets the updated DT from 
OpenSBI.


> I was able to verify the latest DT patch serie from Paul with:
> OpenSBI + U-Boot + Linux & DT.
>
> Following the OpenSBI documentation [0] with U-Boot payload:
> FW_PAYLOAD_PATH=<u-boot_build_dir>/u-boot.bin
>
> I get an U-Boot prompt and then I can just load the linux kernel and
> device tree from the network.

Cool. This approach will also work where DT is loaded separately after 
U-Boot is booted.

> [0]: https://github.com/riscv/opensbi/blob/master/docs/platform/sifive_fu540.md#building-sifive-fu540-platform
>
> > Network booting is still not working as the clock driver probe doesn't
> > happen because of the updated DT.
> >
> > --
> > Regards,
> > Atish


--
Regards,
Atish