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 23:13:10 -0500
From:	Jacob Shin <jacob.shin@....com>
To:	Yinghai Lu <yinghai@...nel.org>
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 06:25:38PM -0700, Yinghai Lu wrote:
> 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.

It actually gets moved out to another function in patch 3/5

> 
> 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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