linux-kernel - Re: linux-next: manual merge of the devicetree tree with the powerpc tree

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Message-ID: <87r1ldt0pd.fsf@mpe.ellerman.id.au>
Date:   Fri, 19 Feb 2021 10:28:46 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Rob Herring <robherring2@...il.com>,
        Stephen Rothwell <sfr@...b.auug.org.au>
Cc:     PowerPC <linuxppc-dev@...ts.ozlabs.org>,
        Hari Bathini <hbathini@...ux.ibm.com>,
        Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Next Mailing List <linux-next@...r.kernel.org>
Subject: Re: linux-next: manual merge of the devicetree tree with the
 powerpc tree

Rob Herring <robherring2@...il.com> writes:
> On Thu, Feb 18, 2021 at 5:34 AM Stephen Rothwell <sfr@...b.auug.org.au> wrote:
>> On Thu, 18 Feb 2021 21:44:37 +1100 Michael Ellerman <mpe@...erman.id.au> wrote:
>> >
>> > I think it just needs this?
>> >
>> > diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
>> > index 87e34611f93d..0492ca6003f3 100644
>> > --- a/arch/powerpc/kexec/elf_64.c
>> > +++ b/arch/powerpc/kexec/elf_64.c
>> > @@ -104,7 +104,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
>> >
>> >       fdt = of_kexec_alloc_and_setup_fdt(image, initrd_load_addr,
>> >                                          initrd_len, cmdline,
>> > -                                        fdt_totalsize(initial_boot_params));
>> > +                                        kexec_fdt_totalsize_ppc64(image));
>> >       if (!fdt) {
>> >               pr_err("Error setting up the new device tree.\n");
>> >               ret = -EINVAL;
>> >
>>
>> I thought about that, but the last argument to
>> of_kexec_alloc_and_setup_fdt() is extra_fdt_size and the allocation
>> done is for this:
>>
>> fdt_size = fdt_totalsize(initial_boot_params) +
>>                    (cmdline ? strlen(cmdline) : 0) +
>>                    FDT_EXTRA_SPACE +
>>                    extra_fdt_size;
>>
>> and kexec_fdt_totalsize_ppc64() also includes
>> fdt_totalsize(initial_boot_params) so I was not sure.  Maybe
>> kexec_fdt_totalsize_ppc64() needs modification as well?
>
> You're both right. Michael's fix is sufficient for the merge. The only
> risk with a larger size is failing to allocate it, but we're talking
> only 10s of KB. Historically until the commit causing the conflict,
> PPC was just used 2x fdt_totalsize(initial_boot_params). You could
> drop 'fdt_size = fdt_totalsize(initial_boot_params) + (2 *
> COMMAND_LINE_SIZE);' from kexec_fdt_totalsize_ppc64() as well, but
> then the function name is misleading.
>
> Lakshmi can send a follow-up patch to fine tune the size and rename
> kexec_fdt_totalsize_ppc64.

Sounds good.

cheers