All of lore.kernel.org
 help / color / mirror / Atom feed
From: Andrea Arcangeli <aarcange@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-stable@nongnu.org, Eduardo Habkost <ehabkost@redhat.com>,
	Gleb Natapov <gleb@redhat.com>,
	qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] fix guest physical bits to match host, to go beyond 1TB guests
Date: Tue, 16 Jul 2013 20:06:03 +0200	[thread overview]
Message-ID: <20130716180603.GD23279@redhat.com> (raw)
In-Reply-To: <51E5876B.2040500@redhat.com>

-On Tue, Jul 16, 2013 at 07:48:27PM +0200, Paolo Bonzini wrote:
> Il 16/07/2013 19:46, Paolo Bonzini ha scritto:
> >>> >> (see PUD with bit >=40 set)
> >> > 
> >> > I am not sure I understand what caused this: if we are advertising 40
> >> > physical bits to the guest, why are we ending up with a PUD with
> >> > bit >= 40 set?
> > Because we create a guest that has bigger memory than what we advertise
> > in CPUID.
> > 
> 
> Also, note that the guest does not really care about this CPUID.  It is
> only used by KVM itself to decide which bits in the page tables are
> reserved.

Yes, I suppose guests thinks if there's >1TB of RAM there are enough
bits in the pagetables to map whatever RAM "range" was found.

About migrating >1TB guests it will be possible as soon as qemu starts
to use the remap_anon_pages+MADV_USERFAULT two features I posted on
linux-kernel recently. With those two features, qemu should start to
provide postcopy live migration by default and after pre-copy is
complete, it will never need to freeze a guest in the source node
anymore.

  reply	other threads:[~2013-07-16 18:06 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-16 17:22 [Qemu-devel] [PATCH] fix guest physical bits to match host, to go beyond 1TB guests Andrea Arcangeli
2013-07-16 17:26 ` Paolo Bonzini
2013-07-16 17:38 ` Eduardo Habkost
2013-07-16 17:46   ` Paolo Bonzini
2013-07-16 17:48     ` Paolo Bonzini
2013-07-16 18:06       ` Andrea Arcangeli [this message]
2013-07-16 18:11     ` Eduardo Habkost
2013-07-16 19:24       ` Paolo Bonzini
2013-07-16 19:42         ` Eduardo Habkost
2013-07-17  8:09           ` Paolo Bonzini
2013-07-17 13:39             ` Eduardo Habkost
2013-07-17 14:01               ` Paolo Bonzini
2013-07-17 15:19           ` Gleb Natapov
2013-07-17 21:20             ` Eduardo Habkost

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20130716180603.GD23279@redhat.com \
    --to=aarcange@redhat.com \
    --cc=ehabkost@redhat.com \
    --cc=gleb@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=qemu-devel@nongnu.org \
    --cc=qemu-stable@nongnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.