linux-kernel - Re: [PATCH v3 3/5] x86: Call efi_memblock_x86_reserve

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Date:	Wed, 26 Mar 2014 13:00:09 +0000
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Daniel Kiper <daniel.kiper@...cle.com>
Cc:	linux-efi@...r.kernel.org, linux-ia64@...r.kernel.org,
	linux-kernel@...r.kernel.org, x86@...nel.org,
	xen-devel@...ts.xenproject.org, boris.ostrovsky@...cle.com,
	david.vrabel@...rix.com, eshelton@...ox.com, fenghua.yu@...el.com,
	hpa@...or.com, ian.campbell@...rix.com, jbeulich@...e.com,
	jeremy@...p.org, konrad.wilk@...cle.com, matt.fleming@...el.com,
	mingo@...hat.com, stefano.stabellini@...citrix.com,
	tglx@...utronix.de, tony.luck@...el.com
Subject: Re: [PATCH v3 3/5] x86: Call efi_memblock_x86_reserve_range() on
 native EFI platform only

On Tue, 25 Mar, at 09:57:54PM, Daniel Kiper wrote:
> Call efi_memblock_x86_reserve_range() on native EFI platform only.
> This is not needed and even it should not be called on platforms
> which wraps EFI infrastructure like Xen.
> 
> Signed-off-by: Daniel Kiper <daniel.kiper@...cle.com>
> ---
>  arch/x86/kernel/setup.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index ce72964..992b67a 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -933,7 +933,7 @@ void __init setup_arch(char **cmdline_p)
>  		set_bit(EFI_64BIT, &x86_efi_facility);
>  	}
>  
> -	if (efi_enabled(EFI_BOOT))
> +	if (!strncmp((char *)&boot_params.efi_info.efi_loader_signature, "EL", 2))
>  		efi_memblock_x86_reserve_range();
>  #endif

This could do with a little bit more explanation. Why is it not
necessary to mark the EFI memory map that was passed to the kernel as
reserved in memblock?

-- 
Matt Fleming, Intel Open Source Technology Center
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