linux-kernel - Re: [PATCH v17 02/10] of: Add a common kexec FDT setup function

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Date:   Wed, 10 Feb 2021 09:59:45 -0800
From:   Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
To:     Rob Herring <robh@...nel.org>
Cc:     zohar@...ux.ibm.com, bauerman@...ux.ibm.com,
        takahiro.akashi@...aro.org, gregkh@...uxfoundation.org,
        will@...nel.org, joe@...ches.com, catalin.marinas@....com,
        mpe@...erman.id.au, james.morse@....com, sashal@...nel.org,
        benh@...nel.crashing.org, paulus@...ba.org, frowand.list@...il.com,
        vincenzo.frascino@....com, mark.rutland@....com,
        dmitry.kasatkin@...il.com, jmorris@...ei.org, serge@...lyn.com,
        pasha.tatashin@...een.com, allison@...utok.net,
        masahiroy@...nel.org, mbrugger@...e.com, hsinyi@...omium.org,
        tao.li@...o.com, christophe.leroy@....fr,
        prsriva@...ux.microsoft.com, balajib@...ux.microsoft.com,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v17 02/10] of: Add a common kexec FDT setup function

On 2/10/21 9:23 AM, Rob Herring wrote:
> On Tue, Feb 09, 2021 at 10:21:52AM -0800, Lakshmi Ramasubramanian wrote:
>> From: Rob Herring <robh@...nel.org>
>>
>> Both arm64 and powerpc do essentially the same FDT /chosen setup for
>> kexec.  The differences are either omissions that arm64 should have
>> or additional properties that will be ignored.  The setup code can be
>> combined and shared by both powerpc and arm64.
>>
>> The differences relative to the arm64 version:
>>   - If /chosen doesn't exist, it will be created (should never happen).
>>   - Any old dtb and initrd reserved memory will be released.
>>   - The new initrd and elfcorehdr are marked reserved.
>>   - "linux,booted-from-kexec" is set.
>>
>> The differences relative to the powerpc version:
>>   - "kaslr-seed" and "rng-seed" may be set.
>>   - "linux,elfcorehdr" is set.
>>   - Any existing "linux,usable-memory-range" is removed.
>>
>> Combine the code for setting up the /chosen node in the FDT and updating
>> the memory reservation for kexec, for powerpc and arm64, in
>> of_kexec_alloc_and_setup_fdt() and move it to "drivers/of/kexec.c".
>>
>> Signed-off-by: Rob Herring <robh@...nel.org>
>> Signed-off-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
>> ---
>>   drivers/of/Makefile |   6 ++
>>   drivers/of/kexec.c  | 258 ++++++++++++++++++++++++++++++++++++++++++++
>>   include/linux/of.h  |  13 +++
>>   3 files changed, 277 insertions(+)
>>   create mode 100644 drivers/of/kexec.c


>> diff --git a/include/linux/of.h b/include/linux/of.h
>> index 4b27c9a27df3..f0eff5e84353 100644
>> --- a/include/linux/of.h
>> +++ b/include/linux/of.h
>> @@ -560,6 +560,19 @@ int of_map_id(struct device_node *np, u32 id,
>>   
>>   phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
>>   
>> +/*
>> + * Additional space needed for the buffer to build the new FDT
>> + * so that we can add initrd, bootargs, kaslr-seed, rng-seed,
>> + * userable-memory-range and elfcorehdr.
>> + */
>> +#define FDT_EXTRA_SPACE 0x1000
> 
> No need for this to be public now. Move it to of/kexec.c.
> 

Will do.

  -lakshmi