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From: "Jan Beulich" <JBeulich@suse.com>
To: <douly.fnst@cn.fujitsu.com>, <tglx@linutronix.de>
Cc: <linux-kernel@vger.kernel.org>
Subject: recent patch "x86/acpi: Prevent X2APIC id 0xffffffff from being accounted"
Date: Fri, 27 Apr 2018 01:21:44 -0600	[thread overview]
Message-ID: <5AE2CF8802000078001BF017@prv1-mh.provo.novell.com> (raw)

Hello,

I've just stumbled across this commit, and I'm wondering if that's actually
correct (I too have at least one system where such IDs are reported in
MADT): For offline/absent CPUs, the firmware may not know the APIC IDs
at the point MADT is built, so I think it is quite reasonable to put ~0 in
there. The ACPID spec specifically calls out that the IDs must not change
across sleep states, which implies to me that they may change across an
offline period of a CPU. IOW I think such entries still need to contribute to
the count of disabled CPUs.

I notice a similar change has been done for the xAPIC case a while ago
by you, Thomas.

Jan

             reply	other threads:[~2018-04-27  7:21 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-27  7:21 Jan Beulich [this message]
2018-04-27  8:32 ` Dou Liyang
2018-04-27 12:09   ` Jan Beulich
2018-05-02  1:56     ` Dou Liyang
2018-05-02  6:39       ` Jan Beulich
2018-05-02  8:10         ` Dou Liyang

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