linux-kernel - Re: [PATCH] kbuild: Enable armthumb BCJ filter for Thumb-2 kernel

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Date:   Sat, 20 Nov 2021 11:18:39 +0800
From:   Jubin Zhong <zhongjubin@...wei.com>
To:     <lasse.collin@...aani.org>
CC:     <akpm@...ux-foundation.org>, <liaohua4@...wei.com>,
        <linux-kernel@...r.kernel.org>, <wangfangpeng1@...wei.com>,
        <zhongjubin@...wei.com>
Subject: Re: [PATCH] kbuild: Enable armthumb BCJ filter for Thumb-2 kernel

> If a Thumb-2 kernel will always use the ARM-Thumb BCJ filter, one can
> save a few bytes from the pre-boot code by omitting the ARM BCJ filter:
>
> --- a/lib/decompress_unxz.c
> +++ b/lib/decompress_unxz.c
> @@ -129,7 +129,11 @@
>  #	define XZ_DEC_POWERPC
>  #endif
>  #ifdef CONFIG_ARM
> -#	define XZ_DEC_ARM
> +#	ifdef CONFIG_THUMB2_KERNEL
> +#		define XZ_DEC_ARMTHUMB
> +#	else
> +#		define XZ_DEC_ARM
> +#	endif
>  #endif
>  #ifdef CONFIG_IA64
>  #	define XZ_DEC_IA64
>
>> --- a/scripts/xz_wrap.sh
>> +++ b/scripts/xz_wrap.sh
>> @@ -8,6 +8,7 @@
>>  # This file has been put into the public domain.
>>  # You can do whatever you want with this file.
>>  #
>> +. include/config/auto.conf
>
> I suggest adding an empty line before this new line so that it is
> clearly separated from the header comment.
>
>> +if [ -n "${CONFIG_THUMB2_KERNEL}" ];then
>
> I suggest adding a space after the semi-colon: ]; then
>
> With or without the above modifications:

Thanks for your advices. I will incorporate the above modifications and send patch v2.