[PATCH v2 2/3] riscv: Expand the DT size before copy reserved memory node

[Bin Meng]

On Fri, Jun 12, 2020 at 3:18 AM Atish Patra <atishp at atishpatra.org> wrote:
>
> On Wed, Jun 10, 2020 at 2:05 AM Bin Meng <bmeng.cn at gmail.com> wrote:
> >
> > Hi Atish,
> >
> > On Wed, Jun 3, 2020 at 2:23 AM Atish Patra <atishp at atishpatra.org> wrote:
> > >
> > > On Thu, May 28, 2020 at 1:47 AM Bin Meng <bmeng.cn at gmail.com> wrote:
> > > >
> > > > From: Bin Meng <bin.meng at windriver.com>
> > > >
> > > > The FDT blob might not have sufficient space to hold a copy of
> > > > reserved memory node. Expand it before the copy.
> > > >
> > > > Reported-by: Rick Chen <rick at andestech.com>
> > > > Signed-off-by: Bin Meng <bin.meng at windriver.com>
> > > > ---
> > > >
> > > >  arch/riscv/lib/fdt_fixup.c | 6 ++++++
> > > >  1 file changed, 6 insertions(+)
> > > >
> > > > diff --git a/arch/riscv/lib/fdt_fixup.c b/arch/riscv/lib/fdt_fixup.c
> > > > index 5f523f0..1290a64 100644
> > > > --- a/arch/riscv/lib/fdt_fixup.c
> > > > +++ b/arch/riscv/lib/fdt_fixup.c
> > > > @@ -41,6 +41,12 @@ int riscv_fdt_copy_resv_mem_node(const void *src, void *dst)
> > > >                 return 0;
> > > >         }
> > > >
> > > > +       err = fdt_open_into(dst, dst, fdt_totalsize(dst) + 32);
> > >
> > > The size may be bigger than 32 bytes in future given that we may have
> > > multiple reserved pmp regions.
> > > How about calculating the size from the source and using that instead
> > > of a fixed size ?
> > >
> >
> > This looks way too complicated. That means the codes here need to
> > understand the FDT blob binary representation to know exactly how much
> > additional size is needed. By looking at existing calls to
> > fdt_open_into() none of these do such things.
> >
> > I guess we will have to give an estimated size to fit all possible
> > situations. Say there are 16 PMP regions, and one occupies 64 bytes,
> > so we can extend the FDT by 64 * 16 = 1024 bytes. Thoughts ??
> >
>
> That works too. I see we only allocate 256 bytes in OpenSBI.
> Can you send a patch to OpenSBI as well with the above reasoning ?
>

Sure, will do.

Regards,
Bin