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Date:   Thu, 14 Jan 2021 13:07:33 -0800
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Subject: Re: [PATCH 2/2] kbuild: handle excessively long argument lists
From:   Nick Desaulniers <ndesaulniers@google.com>
To:     jjohnson@codeaurora.org
Cc:     eberman@quicinc.com, linux-kbuild@vger.kernel.org,
        linux-kernel@vger.kernel.org, masahiroy@kernel.org,
        michal.lkml@markovi.net, mkalikot@codeaurora.org,
        psodagud@quicinc.com
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> From: Mahesh Kumar Kalikot Veetil <mkalikot@codeaurora.org>
> 
> Modules with a large number of compilation units may be
> exceeding AR and LD command argument list. Handle this gracefully by
> writing the long argument list in a file. The command line options
> read from file are inserted in place of the original @file option.
> 
> The usage is well documented at
> https://www.gnu.org/software/make/manual/html_node/File-Function.html
> 
> Signed-off-by: Mahesh Kumar Kalikot Veetil <mkalikot@codeaurora.org>
> Signed-off-by: Jeff Johnson <jjohnson@codeaurora.org>
> ---
>  scripts/Makefile.build | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 252b7d2..d5ef345 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -425,7 +425,11 @@ $(obj)/lib.a: $(lib-y) FORCE
>  # module is turned into a multi object module, $^ will contain header file
>  # dependencies recorded in the .*.cmd file.
>  quiet_cmd_link_multi-m = LD [M]  $@
> -      cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(filter %.o,$^)
> +      cmd_link_multi-m =					\
> +	$(file >$@.in,$(filter %.o,$^))				\
> +	$(LD) $(ld_flags) -r -o $@ @$@.in;			\
> +	rm -f $@.in
> +endif

Was this build tested?

$ make LLVM=1 LLVM_IAS=1 -j72 defconfig
scripts/Makefile.build:432: *** extraneous 'endif'.  Stop.
make: *** [Makefile:535: scripts_basic] Error 2

(Please cc me on v2)

>  
>  $(multi-used-m): FORCE
>  	$(call if_changed,link_multi-m)
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project