linux-kernel - Re: [PATCH v9 1/5] x86/xsave: Move xsave initialization to after parsing early parameters

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Message-ID: <20171012071841.qq5du2l465icuiln@gmail.com>
Date:   Thu, 12 Oct 2017 09:18:41 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Andi Kleen <andi@...stfloor.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Andi Kleen <ak@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v9 1/5] x86/xsave: Move xsave initialization to after
 parsing early parameters

* Andi Kleen <andi@...stfloor.org> wrote:

> From: Andi Kleen <ak@...ux.intel.com>
> 
> Move the XSAVE initialization code to be after parsing early parameters.
> I don't see any reason why the FPU code needs to be initialized that
> early, nothing else in the initialization phase uses XSAVE.
> This is useful to be able to handle command line parameters in the
> XSAVE initialization code.

But that's not what the patch does:

> ---
>  arch/x86/kernel/cpu/common.c | 2 --
>  arch/x86/kernel/setup.c      | 3 +++
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> index c9176bae7fd8..fd47692e5ce9 100644
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -903,8 +903,6 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
>  	}
>  
>  	setup_force_cpu_cap(X86_FEATURE_ALWAYS);
> -	fpu__init_system(c);

This moves the early _FPU_ initialization code, which is more than just xstate 
related...

Also, this is fundamentally a CPU initialization sequence, and this change 
detaches it from the early CPU initialization code. If you want to parse early 
parameters you can add it to fpu__init_parse_early_param() which is there for that 
exact reason.

Also, please fix the titles of your patches as well, you routinely get the 
prefixes wrong, 'git log' should give you an idea about what the current title 
pattern is for FPU code modifications.

Thanks,

	Ingo