From: Gleb Natapov <gleb@redhat.com>
To: Christoph Lechner <cl0059@l-mx.de>
Cc: dbareiro@gmx.net, kvm@vger.kernel.org
Subject: Re: kvm-88: KVM_APIC_READ: read reserved register b0
Date: Sun, 30 Aug 2009 14:49:59 +0300 [thread overview]
Message-ID: <20090830114959.GV30093@redhat.com> (raw)
In-Reply-To: <4A9A6596.3010302@l-mx.de>
On Sun, Aug 30, 2009 at 01:42:14PM +0200, Christoph Lechner wrote:
> Gleb Natapov wrote:
> > This printk no longer exists in upstream kvm.
> >
>
> just to be curious: What was the reason to add that debugging message?
>
Because well behaved OS shouldn't read write only register. Unfortunately
older Linux kernels sometimes uses xchg to access eoi(b0) apic register
which will generate read/write.
> I don't know much about the background of the message, but I assume that
> it is useful. So wouldn't it be a idea to keep the code for the message
> where it is and just throttle the rate it is reported?
>
It's not too much useful unless you are debugging a guest.
--
Gleb.
next prev parent reply other threads:[~2009-08-30 11:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-28 10:04 kvm-88: KVM_APIC_READ: read reserved register b0 Christoph Lechner
2009-08-29 16:37 ` Christoph Lechner
2009-08-29 21:20 ` Daniel Bareiro
2009-08-30 9:59 ` Christoph Lechner
2009-08-30 10:01 ` Gleb Natapov
2009-08-30 11:42 ` Christoph Lechner
2009-08-30 11:49 ` Gleb Natapov [this message]
2009-08-30 15:28 ` Daniel Bareiro
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=20090830114959.GV30093@redhat.com \
--to=gleb@redhat.com \
--cc=cl0059@l-mx.de \
--cc=dbareiro@gmx.net \
--cc=kvm@vger.kernel.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