linux-kernel - Re: [RFC, PATCHv1 17/28] x86/mm: define virtual memory map for 5-level paging

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Date:   Thu, 8 Dec 2016 22:24:37 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        "H. Peter Anvin" <hpa@...or.com>, Andi Kleen <ak@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Andy Lutomirski <luto@...capital.net>,
        linux-arch@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC, PATCHv1 17/28] x86/mm: define virtual memory map for
 5-level paging

On Thu, Dec 08, 2016 at 10:56:04AM -0800, Randy Dunlap wrote:
> > @@ -23,6 +23,27 @@ ffffffffa0000000 - ffffffffff5fffff (=1526 MB) module mapping space
> >  ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls
> >  ffffffffffe00000 - ffffffffffffffff (=2 MB) unused hole
> >  
> > +Virtual memory map with 5 level page tables:
> > +
> > +0000000000000000 - 00ffffffffffffff (=56 bits) user space, different per mm
> > +hole caused by [57:63] sign extension
> 
> Can you briefly explain the sign extension?

Sure, I'll update it on respin.

> Should that be [56:63]?

You're right, it should. 

Thanks for all your corrections.

-- 
 Kirill A. Shutemov