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Message-ID: <CAE9FiQWKbqnU_6-W70tDYq7rL=r7vHzYKUo5PwOzgwUtTVxQwA@mail.gmail.com>
Date: Fri, 7 Oct 2016 11:55:39 -0700
From: Yinghai Lu <yinghai@...nel.org>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Dou Liyang <douly.fnst@...fujitsu.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>,
"linux-tip-commits@...r.kernel.org"
<linux-tip-commits@...r.kernel.org>,
Tony Luck <tony.luck@...el.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
"lenb@...nel.org" <lenb@...nel.org>,
"Zheng, Lv" <lv.zheng@...el.com>,
Bob Moore <robert.moore@...el.com>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Subject: Re: [tip:x86/apic] x86/acpi: Introduce persistent storage for cpuid
<-> apicid mapping
On Fri, Oct 7, 2016 at 6:00 AM, Thomas Gleixner <tglx@...utronix.de> wrote:
> On Fri, 7 Oct 2016, Thomas Gleixner wrote:
>> On Fri, 7 Oct 2016, Dou Liyang wrote:
>> > Is it possible that the "-1/oxffffffff" could appear in the MADT which is one
>> > of the ACPI tables?
>>
>> According to the SDM the x2apic id is a 32bit ID, so 0xffffffff is a
>> legitimate value.
>
> The ACPI spec says that bit 0 of the x2apic flags field tells whether the
> logical processor is present or not. So the proper check for x2apic is that
> flag.
>
> The lapic structure has the same flag, but the kernel ignores the flags for
> both lapic and x2apic.
>
> I'm going to apply the minimal fix of checking for id == 0xff in
> acpi_lapic_parse() for now, but this needs to be revisited and fixed
> proper.
Good to me. Thanks for fixing it.
Yinghai
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