Re: [PATCH] RISC-V: Place DTB at 3GB boundary instead of 4GB

[Bin Meng]

Hi Atish,

On Wed, Jan 6, 2021 at 7:44 AM Atish Patra <Atish.Patra@wdc.com> wrote:
>
> On Tue, 2021-01-05 at 11:11 +0800, Bin Meng wrote:
> > On Fri, Dec 18, 2020 at 5:48 AM Atish Patra <atish.patra@wdc.com>
> > wrote:
> > >
> > > Currently, we place the DTB at 2MB from 4GB or end of DRAM which
> > > ever is
> > > lesser. However, Linux kernel can address only 1GB of memory for
> > > RV32.
> > > Thus, it can not map anything beyond 3GB (assuming 2GB is the
> > > starting address).
> > > As a result, it can not process DT and panic if opensbi dynamic
> > > firmware
> > > is used.
> > >
> > > Fix this by placing the DTB at 2MB from 3GB or end of DRAM
> > > whichever is lower.
> > >
> >
> > Fixes: 66b1205bc5ab ("RISC-V: Copy the fdt in dram instead of ROM")
> >
>
> Just to clarify, it is not a bug in the original patch. This bug
> appeared in recent kernel because kernel(from v5.10) doesn't use fixmap
> for DT processing anymore. Thus, the DT has to be placed at location
> that can be addressed by kernel.

Thanks for the clarification.

>
> I will add the fixes tag.
>

Did you get a chance to trace to another possible kernel bug?

Regards,
Bin