From: "Jan Beulich" <JBeulich@novell.com>
To: Natalie Protasevich <protasnb@gmail.com>
Cc: xen-devel@lists.xensource.com
Subject: Re: Alignment check on domU (2.6.32)
Date: Tue, 30 Mar 2010 09:06:12 +0100 [thread overview]
Message-ID: <4BB1CD140200007800037BF6@vpn.id2.novell.com> (raw)
In-Reply-To: <32209efe1003292008y5880e9bfib238c089377b4ba7@mail.gmail.com>
>>> Natalie Protasevich <protasnb@gmail.com> 30.03.10 05:08 >>>
> I cheated and cleared the AM flag in cr0 (as one can see in this
> trace) but this didn't help.
Assuming you did this in the hypervisor, this would point at a CPU bug.
There should not be any alignment check exceptions with this bit clear.
> I haven't figured out what sets the AM flag...
The hypervisor sets up CR0 this way, and doesn't allow altering later.
In order to allow the kernel to support alignment check exceptions
for user mode, Xen needs to do it this way and clears AC each time
passing control to (64-bit) kernel code.
What you'll need to do is look for where AC gets set, probably by
modifying all asm-s using popf, as this is what seems bogus.
Jan
next prev parent reply other threads:[~2010-03-30 8:06 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-30 3:08 Alignment check on domU (2.6.32) Natalie Protasevich
2010-03-30 8:06 ` Jan Beulich [this message]
2010-03-30 11:34 ` Natalie Protasevich
2010-03-30 16:53 ` Jeremy Fitzhardinge
2010-03-30 17:32 ` Natalie Protasevich
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=4BB1CD140200007800037BF6@vpn.id2.novell.com \
--to=jbeulich@novell.com \
--cc=protasnb@gmail.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 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).