From: "H. Peter Anvin" <hpa@zytor.com>
To: Yinghai Lu <yinghai@kernel.org>
Cc: "Zhang, Lin-Bao (Linux Kernel R&D)" <linbao.zhang@hp.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"alan@lxorguk.ukuu.org.uk" <alan@lxorguk.ukuu.org.uk>,
"mingo@redhat.com" <mingo@redhat.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"x86@kernel.org" <x86@kernel.org>,
"a.p.zijlstra@chello.nl" <a.p.zijlstra@chello.nl>,
"jarkko.sakkinen@intel.com" <jarkko.sakkinen@intel.com>,
"joerg.roedel@amd.com" <joerg.roedel@amd.com>,
"agordeev@redhat.com" <agordeev@redhat.com>
Subject: Re: Why Linux kernel forced to enter X2APIC mode( just because of booting cpu has supported x2apic) without depending on BIOS' setting in MSR->x2apic enablement bit ?
Date: Wed, 19 Dec 2012 08:10:21 -0800 [thread overview]
Message-ID: <50D1E6ED.2070803@zytor.com> (raw)
In-Reply-To: <CAE9FiQUT0NZq=6JBAY4mFNx0eBxDr6fNDGQ0GW9OtxUMXJQ21w@mail.gmail.com>
On 12/18/2012 09:49 AM, Yinghai Lu wrote:
>
> So you need to make cpuid show does not support x2apic --- check with
> intel they have way to do that.
>
No, but there is a flag in ACPI that "this BIOS is broken with x2APIC".
Setting that flag as opposed to fixing the bugs, though is very much not
recommended, however; the lack of interrupt routing means there are ways
for a rogue device to compromise the security provided by VT-d, see:
http://www.invisiblethingslab.com/resources/2011/Software%20Attacks%20on%20Intel%20VT-d.pdf
-hpa
prev parent reply other threads:[~2012-12-19 16:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-18 9:50 Zhang, Lin-Bao (Linux Kernel R&D)
2012-12-18 17:49 ` Yinghai Lu
2012-12-19 10:13 ` Zhang, Lin-Bao (Linux Kernel R&D)
2012-12-19 16:03 ` Yinghai Lu
2012-12-19 10:36 ` Zhang, Lin-Bao (Linux Kernel R&D)
2012-12-19 16:05 ` Yinghai Lu
2012-12-20 10:38 ` Zhang, Lin-Bao (Linux Kernel R&D)
2012-12-20 16:46 ` Yinghai Lu
2012-12-20 16:48 ` H. Peter Anvin
2012-12-19 16:10 ` H. Peter Anvin [this message]
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