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Date: Fri, 22 Nov 2024 17:55:52 +0100
From: Ingo Molnar <mingo@kernel.org>
To: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>, x86-ml <x86@kernel.org>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] x86/boot: Get rid of linux/init.h include
Message-ID: <Z0C3mDCngAf7ErM2@gmail.com>
References: <20241122163139.GAZ0Cx63Ia9kgYgRIr@fat_crate.local>
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* Borislav Petkov (AMD) <bp@alien8.de> wrote:

> 
> this is what I think we should do (just a first patch) to decouple the
> decompressor from kernel proper headers namespace so that there's no
> collisions and ugly ifdeffery when those kernel proper headers get shared.
> 
> And if we want to share things, we will use asm/shared/ to put such shared
> definitions there.
> 
> Thoughts?

Sounds good.


> --- a/arch/x86/boot/compressed/head_32.S
> +++ b/arch/x86/boot/compressed/head_32.S
> @@ -24,7 +24,6 @@
>   */
>  	.text
>  
> -#include <linux/init.h>
>  #include <linux/linkage.h>
>  #include <asm/segment.h>
>  #include <asm/page_types.h>
> @@ -32,6 +31,10 @@
>  #include <asm/asm-offsets.h>
>  #include <asm/bootparam.h>
>  
> +#ifdef KERNEL_PROPER_HEADER
> +#error Do not include kernel proper namespace headers
> +#endif

The canonical solution in such cases is to use the existing header 
guard, ie:

 #ifdef _LINUX_INIT_H
 # error Do not include kernel proper namespace headers
 #endif

Then we can skip defining KERNEL_PROPER_HEADER as well, and this change 
will be purely to x86 code.

Thanks,

	Ingo