linux-kernel - Re: [PATCH 1/5] x86: Move enabling of PSE and PGE out of init_memory

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Date:	Fri, 24 Aug 2012 18:25:38 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Jacob Shin <jacob.shin@....com>
Cc:	X86-ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>, Tejun Heo <tj@...nel.org>,
	Dave Young <dyoung@...hat.com>,
	Chao Wang <chaowang@...hat.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	Andreas Herrmann <andreas.herrmann3@....com>,
	Borislav Petkov <borislav.petkov@....com>
Subject: Re: [PATCH 1/5] x86: Move enabling of PSE and PGE out of init_memory_mapping

On Fri, Aug 24, 2012 at 4:55 PM, Jacob Shin <jacob.shin@....com> wrote:
> Depending on the platform, init_memory_mapping() may be called multiple
> times. Move it out to setup_arch() to avoid writing to cr4 on every call.
>
> Signed-off-by: Jacob Shin <jacob.shin@....com>
> ---
>  arch/x86/kernel/setup.c |   10 ++++++++++
>  arch/x86/mm/init.c      |   10 ----------
>  2 files changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index f4b9b80..751e020 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -913,6 +913,16 @@ void __init setup_arch(char **cmdline_p)
>
>         init_gbpages();
>
> +       /* Enable PSE if available */
> +       if (cpu_has_pse)
> +               set_in_cr4(X86_CR4_PSE);
> +
> +       /* Enable PGE if available */
> +       if (cpu_has_pge) {
> +               set_in_cr4(X86_CR4_PGE);
> +               __supported_pte_mask |= _PAGE_GLOBAL;
> +       }
> +

please don't put it directly in setup_arch().

and another function.

Thanks

Yinghai

>         /* max_pfn_mapped is updated here */
>         max_low_pfn_mapped = init_memory_mapping(0, max_low_pfn<<PAGE_SHIFT);
>         max_pfn_mapped = max_low_pfn_mapped;
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index e0e6990..2f07e09 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -149,16 +149,6 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
>         use_gbpages = direct_gbpages;
>  #endif
>
> -       /* Enable PSE if available */
> -       if (cpu_has_pse)
> -               set_in_cr4(X86_CR4_PSE);
> -
> -       /* Enable PGE if available */
> -       if (cpu_has_pge) {
> -               set_in_cr4(X86_CR4_PGE);
> -               __supported_pte_mask |= _PAGE_GLOBAL;
> -       }
> -
>         if (use_gbpages)
>                 page_size_mask |= 1 << PG_LEVEL_1G;
>         if (use_pse)
> --
> 1.7.9.5
>
>
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