linux-kernel - Re: [PATCH -fixes v2 3/3] riscv: No need to relocate the dtb as it lies in the fixmap region

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Date:   Wed, 29 Mar 2023 16:33:45 +0100
From:   Conor Dooley <conor@...nel.org>
To:     Alexandre Ghiti <alexghiti@...osinc.com>
Cc:     Jonathan Corbet <corbet@....net>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Conor Dooley <conor.dooley@...rochip.com>,
        linux-doc@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH -fixes v2 3/3] riscv: No need to relocate the dtb as it
 lies in the fixmap region

On Wed, Mar 29, 2023 at 04:40:18PM +0200, Alexandre Ghiti wrote:
> On Wed, Mar 29, 2023 at 3:56 PM Conor Dooley <conor@...nel.org> wrote:
> >
> > On Wed, Mar 29, 2023 at 10:19:32AM +0200, Alexandre Ghiti wrote:
> > > We used to access the dtb via its linear mapping address but now that the
> > > dtb early mapping was moved in the fixmap region, we can keep using this
> > > address since it is present in swapper_pg_dir, and remove the dtb
> > > relocation.
> > >
> > > Note that the relocation was wrong anyway since early_memremap() is
> > > restricted to 256K whereas the maximum fdt size is 2MB.
> >
> > So, should this be marked as a fix, and backported along with 1/3?
> 
> Hmmm the whole series should be backported, it does not make sense to
> move the dtb mapping and keep accessing it using its linear mapping
> address since it could fail for the exact reason the relocation was
> implemented in the first place and the relocation is wrong.
> 
> Maybe we should simply add a "Cc: stable@...r.kernel.org" on all the patches?

Yup, although hopefully Palmer can handle that if nothing else needs
changing.

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