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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Arjan van de Ven <arjan@linux.intel.com>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     x86@kernel.org, Tom Lendacky <thomas.lendacky@amd.com>,
        Andrew Cooper <andrew.cooper3@citrix.com>,
        Huang Rui <ray.huang@amd.com>, Juergen Gross <jgross@suse.com>,
        Dimitri Sivanich <dimitri.sivanich@hpe.com>,
        Michael Kelley <mikelley@microsoft.com>,
        Sohil Mehta <sohil.mehta@intel.com>,
        K Prateek Nayak <kprateek.nayak@amd.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Zhang Rui <rui.zhang@intel.com>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Feng Tang <feng.tang@intel.com>,
        Andy Shevchenko <andy@infradead.org>
Subject: Re: [patch 02/53] x86/cpu/topology: Make the APIC mismatch warnings
 complete
In-Reply-To: <c21f9f42-d270-d9be-b94e-de4d4b6e5ad5@linux.intel.com>
References: <20230807130108.853357011@linutronix.de>
 <20230807135026.528433010@linutronix.de>
 <c21f9f42-d270-d9be-b94e-de4d4b6e5ad5@linux.intel.com>
Date:   Mon, 07 Aug 2023 16:54:03 +0200
Message-ID: <877cq6vr78.ffs@tglx>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Mon, Aug 07 2023 at 07:28, Arjan van de Ven wrote:

> On 8/7/2023 6:52 AM, T
>>   
>> --- a/arch/x86/kernel/cpu/topology_common.c
>> +++ b/arch/x86/kernel/cpu/topology_common.c
>> @@ -176,6 +176,16 @@ void cpu_parse_topology(struct cpuinfo_x
>>   
>>   	parse_topology(&tscan, false);
>>   
>> +	if (c->topo.initial_apicid != c->topo.apicid) {
>> +		pr_err(FW_BUG "CPU%4u: APIC ID mismatch. CPUID: 0x%04x APIC: 0x%04x\n",
>> +		       cpu, c->topo.initial_apicid, c->topo.apicid);
>> +	}
>> +
>> +	if (c->topo.apicid != cpuid_to_apicid[cpu]) {
>> +		pr_err(FW_BUG "CPU%4u: APIC ID mismatch. Firmware: 0x%04x APIC: 0x%04x\n",
>> +		       cpu, cpuid_to_apicid[cpu], c->topo.apicid);
>> +	}
>> +
>
> while these messages are basically the same as current ones they are short one key thing for the user
> ... which one of the two will be used. Yes one can look up in the source code where the message comes from
> and reverse engineer that... or we can just add this to these pr_err() messages
>
>
> like
>
> pr_err(FW_BUG "CPU%4u: APIC ID mismatch. CPUID: 0x%04x APIC: 0x%04x. APIC value will be used.\n",
> 		       cpu, c->topo.initial_apicid, c->topo.apicid);

Good point.