linux-kernel - Re: [PATCH 3/3] mtrr, mm, x86: Enhance MTRR checks for KVA huge page mapping

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Date:	Thu, 12 Mar 2015 07:58:18 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"hpa@...or.com" <hpa@...or.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"arnd@...db.de" <arnd@...db.de>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"dave.hansen@...el.com" <dave.hansen@...el.com>,
	"Elliott, Robert (Server Storage)" <Elliott@...com>,
	"pebolle@...cali.nl" <pebolle@...cali.nl>
Subject: Re: [PATCH 3/3] mtrr, mm, x86: Enhance MTRR checks for KVA huge
 page mapping

On Thu, 2015-03-12 at 11:03 +0000, Ingo Molnar wrote:
> * Toshi Kani <toshi.kani@...com> wrote:
> 
> > > Did it perhaps want to be the other way around:
> > > 
> > >         if (mtrr_state.have_fixed && (start < 0x1000000)) {
> > > 	...
> > >                 } else if (start < 0x100000) {
> > > 	...
> > > 
> > > or did it simply mess up the condition?
> > 
> > I think it was just paranoid to test the same condition twice...
> 
> Read the code again, it's _not_ the same condition ...

Oh, I see...  It must be a typo.  The fixed range is 0x0 to 0xFFFFF, so
it only makes sense to check with (start < 0x100000).

Thanks,
-Toshi

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