All of lore.kernel.org
 help / color / mirror / Atom feed
From: Mukesh Rathor <mukesh.rathor@oracle.com>
To: Keir Fraser <keir.fraser@eu.citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Subject: Re: 32bit PAE PV guest on 64bit hypervisor
Date: Wed, 22 Apr 2009 18:57:46 -0700	[thread overview]
Message-ID: <49EFCB1A.60202@oracle.com> (raw)
In-Reply-To: <C609EBB5.8831%keir.fraser@eu.citrix.com>



Keir Fraser wrote:
> On 14/04/2009 04:39, "Mukesh Rathor" <mukesh.rathor@oracle.com> wrote:
> 
..
> Implementing clear_fixmap() with set_pte() is not correct, even on native.
> Since it clears high then low, it temporarily leaves you with a possibly
> invalid present PTE -- even on native this can cause problems if e.g., the
> invalid PTE maps uncacheable I/O memory.
> 
> In our kernel we simply solved this by implementing __set_fixmap() with a
> hypercall that could update all 64 bits at once. An alternative is indeed to
> clear low then high. Basically, clearing a pte has to be done the opposite
> way round to setting a pte.
> 
>  -- Keir

Just a quick update, I changed to hypercall and it worked.  BTW, I also had to 
increase the __PHYSICAL_MASK_SHIFT in guest (to 40) as I'm on system with 
128GB. With both changes in the 32bit PAE guest, it's doing OK now.

Thanks for the help.
Mukesh

  reply	other threads:[~2009-04-23  1:57 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-14  3:39 32bit PAE PV guest on 64bit hypervisor Mukesh Rathor
2009-04-14  6:28 ` Keir Fraser
2009-04-23  1:57   ` Mukesh Rathor [this message]
2009-04-14 15:59 ` Jeremy Fitzhardinge
2009-04-14 18:06   ` Mukesh Rathor

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=49EFCB1A.60202@oracle.com \
    --to=mukesh.rathor@oracle.com \
    --cc=keir.fraser@eu.citrix.com \
    --cc=xen-devel@lists.xensource.com \
    /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.