linux-kernel - Re: [PATCH AUTOSEL for-4.4 39/39] MIPS: Use Makefile.postlink to insert relocations into vmlinux

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Date:   Thu, 9 Nov 2017 09:16:44 +0000
From:   Matt Redfearn <matt.redfearn@...s.com>
To:     "Levin, Alexander (Sasha Levin)" <alexander.levin@....verizon.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     Matt Redfearn <matt.redfearn@...tec.com>,
        "linux-mips@...ux-mips.org" <linux-mips@...ux-mips.org>,
        Ralf Baechle <ralf@...ux-mips.org>
Subject: Re: [PATCH AUTOSEL for-4.4 39/39] MIPS: Use Makefile.postlink to
 insert relocations into vmlinux



On 08/11/17 20:50, Levin, Alexander (Sasha Levin) wrote:
> From: Matt Redfearn <matt.redfearn@...tec.com>
>
> [ Upstream commit 44079d3509aee89c58f3e4fd929fa53ab2299019 ]
>
> When relocatable support for MIPS was merged, there was no support for
> an architecture to add a postlink step for vmlinux. This meant that only
> invoking a target within the boot directory, such as uImage, caused the
> relocations to be inserted into vmlinux. Building just the vmlinux
> target would result in a relocatable kernel with no relocation
> information present.
>
> Commit fbe6e37dab97 ("kbuild: add arch specific post-link Makefile")

Hi,

This patch depends on upstream commit fbe6e37dab97 ("kbuild: add arch 
specific post-link Makefile") which was introduced in v4.9.

This patch is an improvement to the build flow and I would not consider 
it for backporting - certainly not to v4.8 or earlier which is missing 
the dependency. Applying it will not break anything, however, it will 
perform no function either without the supporting dependency.

Thanks,
Matt


> recified this situation, so MIPS can now define a postlink step to add
> relocation information into vmlinux, and remove the additional steps
> tacked onto boot targets.
>
> Signed-off-by: Matt Redfearn <matt.redfearn@...tec.com>
> Tested-by: Steven J. Hill <steven.hill@...ium.com>
> Cc: linux-mips@...ux-mips.org
> Cc: linux-kernel@...r.kernel.org
> Patchwork: https://patchwork.linux-mips.org/patch/14554/
> Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
> Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
> ---
>   arch/mips/Makefile.postlink | 35 +++++++++++++++++++++++++++++++++++
>   1 file changed, 35 insertions(+)
>   create mode 100644 arch/mips/Makefile.postlink
>
> diff --git a/arch/mips/Makefile.postlink b/arch/mips/Makefile.postlink
> new file mode 100644
> index 000000000000..b0ddf0701a31
> --- /dev/null
> +++ b/arch/mips/Makefile.postlink
> @@ -0,0 +1,35 @@
> +# ===========================================================================
> +# Post-link MIPS pass
> +# ===========================================================================
> +#
> +# 1. Insert relocations into vmlinux
> +
> +PHONY := __archpost
> +__archpost:
> +
> +include include/config/auto.conf
> +include scripts/Kbuild.include
> +
> +CMD_RELOCS = arch/mips/boot/tools/relocs
> +quiet_cmd_relocs = RELOCS $@
> +      cmd_relocs = $(CMD_RELOCS) $@
> +
> +# `@...e` prevents complaint when there is nothing to be done
> +
> +vmlinux: FORCE
> +	@true
> +ifeq ($(CONFIG_RELOCATABLE),y)
> +	$(call if_changed,relocs)
> +endif
> +
> +%.ko: FORCE
> +	@true
> +
> +clean:
> +	@true
> +
> +PHONY += FORCE clean
> +
> +FORCE:
> +
> +.PHONY: $(PHONY)