linux-kernel - Re: [PATCH v16 06/16] lib: fdt: add a helper function for handling memory range property

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Date:   Tue, 11 Dec 2018 15:17:16 +0900
From:   "AKASHI, Takahiro" <takahiro.akashi@...aro.org>
To:     James Morse <james.morse@....com>
Cc:     Will Deacon <will.deacon@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        David Howells <dhowells@...hat.com>,
        Vivek Goyal <vgoyal@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        David Miller <davem@...emloft.net>, dyoung@...hat.com,
        Baoquan He <bhe@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        prudo@...ux.ibm.com, Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        bhsharma@...hat.com, kexec@...ts.infradead.org,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Frank Rowand <frowand.list@...il.com>,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v16 06/16] lib: fdt: add a helper function for handling
 memory range property

James,

On Fri, Dec 07, 2018 at 10:12:47AM +0000, James Morse wrote:
> Hi Akashi, Will,
> 
> On 06/12/2018 15:54, Will Deacon wrote:
> > On Thu, Dec 06, 2018 at 08:47:04AM -0600, Rob Herring wrote:
> >> On Wed, Nov 14, 2018 at 11:52 PM AKASHI Takahiro
> >> <takahiro.akashi@...aro.org> wrote:
> >>>
> >>> Added function, fdt_setprop_reg(), will be used later to handle
> >>> kexec-specific property in arm64's kexec_file implementation.
> >>> It will possibly be merged into libfdt in the future.
> >>
> >> You generally can't modify libfdt files. Any changes will be blown
> >> away with the next dtc sync (there's one in -next now). Though here
> >> you are creating a new location with fdt code. lib/ is just a shim to
> >> the actual libfdt code. Don't put any implementation there. You can
> >> add this to drivers/of/fdt_address.c for the short term, but it still
> >> needs to go upstream.
> >>
> >> Otherwise, the implementation looks fine to me.
> > 
> > I agree, but I don't think there's a real need for us to hack
> > drivers/of/fdt_address.c in the meantime -- let's just target upstream
> > and not carry this in the kernel.
> > 
> > Akashi -- for now, I'll drop the kdump parts of this series which rely
> > on this helper. The majority of the series is actually independent and
> > can go in as-is.
> > 
> > I've pushed out a kexec branch to the arm64 tree for you to take a look
> > at:
> > 
> > https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/log/?h=kexec
> 
> I gave this a quick spin. Without the elfcorehdr/usable-memory-range arm64 needs
> to explicitly forbid kdump via kexec_file_load. (like powerpc does already).

Thank you for pointing this out.

> Without this kdump works, but the second kernel overwrites the first as those DT
> properties are missing.
> 
> I'll post a patch momentarily,

Fine, but anyhow I'm going to submit a new version (*without* kdump),
I will fix the issue along with others.

-Takahiro Akashi


> 
> Thanks,
> 
> James
>