linux-kernel - Re: [PATCH 2/2] x86/earlyprintk: setup earlyprintk as possible

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Date:	Tue, 7 Apr 2015 13:07:41 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Alexander Kuleshov <kuleshovmail@...il.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] x86/earlyprintk: setup earlyprintk as possible


* Alexander Kuleshov <kuleshovmail@...il.com> wrote:

> As setup_early_printk passed to the early_param, it will be usable only after
> 'parse_early_param' function will be called from the 'setup_arch'. So we have
> earlyprintk during early boot and decompression. Next point after decompression
> of the kernel where we can use early_printk is after call of the
> 'parse_early_param'.
> 
> This patch removes 'earlyprintk' from the early_param and setup it right after
> boot data copying. So 'early_printk' function will be usabable after
> decompression of kernel and before parse_early_param will be called.
> 
> Kernel with this patch was tested with qemu-i386. early_printk function works
> after early_printk initialization.
> 
> Signed-off-by: Alexander Kuleshov <kuleshovmail@...il.com>
> ---
>  arch/x86/kernel/head32.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
> index 2911ef3..dd0aadc 100644
> --- a/arch/x86/kernel/head32.c
> +++ b/arch/x86/kernel/head32.c
> @@ -34,6 +34,9 @@ asmlinkage __visible void __init i386_start_kernel(void)
>  	cr4_init_shadow();
>  	sanitize_boot_params(&boot_params);
>  
> +	/* setup earlyprintk as early as possible */
> +	setup_early_printk(boot_command_line);

So why not at the beginning of the function?

Thanks,

	Ingo
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