From: Pu Wen <puwen@hygon.cn>
To: Borislav Petkov <bp@alien8.de>
Cc: "tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"hpa@zytor.com" <hpa@zytor.com>,
"x86@kernel.org" <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] x86/cpu/hygon: Fix phys_proc_id calculation logic for multi-die processor
Date: Sat, 23 Mar 2019 18:56:52 +0800 [thread overview]
Message-ID: <e181933e-775a-4597-7700-9dde8b98295f@hygon.cn> (raw)
In-Reply-To: <20190323085934.GB23698@zn.tnic>
On 2019/3/23 16:59, Borislav Petkov wrote:
> On Sat, Mar 23, 2019 at 10:13:39AM +0800, Pu Wen wrote:
>> Current physical id is computed via "phys_proc_id = initial_apicid >>
>> bits".
>>
>> For 4-Die 2 socket system, the physical id of socket 2 is:
>> initial_apicid >> bits = 0b1xxxxxx >> 6 = 1.
>> The result is true.
>>
>> But for 2-Die 2 socket system, the physical id of socket 2 is:
>> initial_apicid >> bits = 0b10xxxxx >> 5 = 2,
>> and for 1-Die 2 socket system, the physical id of socket 2 is:
>> initial_apicid >> bits = 0b100xxxx >> 4 = 4.
>> The results are not correct any more.
>>
>> So the adjustment for the 1-Die/2-Die 2 socket system is needed.
>> And just use ApicId[6], which already defined the right thing, as the
>> socket ID.
>
> I understand all that. But let me repeat my question:
>
> So why do you need to do something different than what AMD does?
>
> You said you're programming the initial APIC ID the same as AMD. So why
> doesn't this need to be changed in AMD code too but only for hygon?
Because AMD doesn't have 2-Socket system with 1-Die/2-Die processors(see
reference [2]). So it will return the right result when getting physical
ID in AMD system.
[2] https://www.amd.com/en/products/specifications/processors
--
Regards,
Pu Wen
next prev parent reply other threads:[~2019-03-23 10:59 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-22 10:43 [RFC PATCH] x86/cpu/hygon: Fix phys_proc_id calculation logic for multi-die processor Pu Wen
2019-03-22 15:54 ` Borislav Petkov
2019-03-22 16:19 ` Pu Wen
2019-03-22 16:44 ` Borislav Petkov
2019-03-22 16:52 ` Peter Zijlstra
2019-03-23 3:00 ` Pu Wen
2019-03-23 1:48 ` Pu Wen
2019-03-23 8:57 ` Borislav Petkov
2019-03-22 17:16 ` Borislav Petkov
2019-03-23 2:13 ` Pu Wen
2019-03-23 8:59 ` Borislav Petkov
2019-03-23 10:56 ` Pu Wen [this message]
2019-03-23 11:08 ` Borislav Petkov
2019-03-23 11:11 ` Pu Wen
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