linux-kernel - Re: 2.6.38.2 breaks suspend to disk

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Message-ID: <4D95FBDD.9050901@zytor.com>
Date:	Fri, 01 Apr 2011 09:22:53 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	Ingo Molnar <mingo@...hat.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Michael Leun <lkml20101129@...ton.leun.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Mike Pagano <mpagano@...too.org>
Subject: Re: 2.6.38.2 breaks suspend to disk

On 04/01/2011 09:06 AM, Yinghai Lu wrote:
> Index: linux-2.6/arch/x86/kernel/setup.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/setup.c
> +++ linux-2.6/arch/x86/kernel/setup.c
> @@ -294,10 +294,17 @@ static void __init init_gbpages(void)
>      else
>          direct_gbpages = 0;
>  }
> +static void __init store_mmu_cr4(void)
> +{
> +    mmu_cr4_features = read_cr4();
> +}
>  #else
>  static inline void init_gbpages(void)
>  {
>  }
> +static void __init store_mmu_cr4(void)
> +{
> +}
>  static void __init cleanup_highmap(void)
>  {
>  }
> @@ -929,6 +936,8 @@ void __init setup_arch(char **cmdline_p)
>      /* 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;
> +    /* after init_memory_mapping updating cr4*/
> +    store_mmu_cr4();
>  
>  #ifdef CONFIG_X86_64
>      if (max_pfn > max_low_pfn) {

This looks really, really, really wrong.

Why the heck should we save and restore CR4 only for x86-64?

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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