From: "Jan Beulich" <JBeulich@suse.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: boris.ostrovsky@oracle.com, Olaf Hering <olaf@aepfle.de>,
david.vrabel@citrix.com, xen-devel@lists.xen.org
Subject: Re: identify a Xen PV domU to fix devmem_is_allowed
Date: Tue, 01 Mar 2016 03:38:55 -0700 [thread overview]
Message-ID: <56D57F4F02000078000D7BD4@prv-mh.provo.novell.com> (raw)
In-Reply-To: <20160229151000.GA17154@char.us.oracle.com>
>>> On 29.02.16 at 16:10, <konrad.wilk@oracle.com> wrote:
> On Mon, Feb 29, 2016 at 11:28:49AM +0100, Olaf Hering wrote:
>> What is the correct way to identify a Xen PV domU in the kenrel?
>> devmem_is_allowed() used to disable access to pages < 256 in domU.
>> With pvops this check was removed, or never ported forward.
>
> CC-ing Boris and Daniel.
>
> Why is this needed? The first 640KB of memory in a guest are
> RAM pages with no BIOS data in it.
Exactly: devmem_is_allowed() is specifically meant to return true
if and only if the page is not RAM or otherwise special. The
question just is whether what Olaf suggested is also correct for
Dom0 - I don't recall whether the low 1Mb gets 1:1 mapped in
that case.
Jan
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
next prev parent reply other threads:[~2016-03-01 10:38 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-29 10:28 identify a Xen PV domU to fix devmem_is_allowed Olaf Hering
2016-02-29 15:10 ` Konrad Rzeszutek Wilk
2016-02-29 15:29 ` Olaf Hering
2016-02-29 18:32 ` Boris Ostrovsky
2016-03-01 15:14 ` Olaf Hering
2016-03-01 10:38 ` Jan Beulich [this message]
2016-03-01 14:34 ` Konrad Rzeszutek Wilk
2016-03-01 14:45 ` Boris Ostrovsky
2016-03-15 16:57 ` Olaf Hering
2016-03-15 18:56 ` Boris Ostrovsky
2016-03-21 21:29 ` Boris Ostrovsky
2016-03-22 18:37 ` Boris Ostrovsky
2016-03-23 8:28 ` Olaf Hering
2016-06-06 21:17 ` Olaf Hering
2016-03-01 16:23 ` Olaf Hering
2016-03-01 15:29 ` David Vrabel
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=56D57F4F02000078000D7BD4@prv-mh.provo.novell.com \
--to=jbeulich@suse.com \
--cc=boris.ostrovsky@oracle.com \
--cc=david.vrabel@citrix.com \
--cc=konrad.wilk@oracle.com \
--cc=olaf@aepfle.de \
--cc=xen-devel@lists.xen.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).