linux-kernel - Re: [RFC part2 PATCH 2/9] ARM64 / ACPI: Prefill cpu possible/present maps and map logical cpu id to APIC id

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Date:	Wed, 4 Dec 2013 09:40:04 -0600
From:	Rob Herring <robherring2@...il.com>
To:	Hanjun Guo <hanjun.guo@...aro.org>
Cc:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	Mark Rutland <mark.rutland@....com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Linaro Patches <patches@...aro.org>,
	Olof Johansson <olof@...om.net>,
	Catalin Marinas <catalin.marinas@....com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linaro-acpi@...ts.linaro.org, linux-acpi@...r.kernel.org,
	Rob Herring <rob.herring@...xeda.com>,
	Grant Likely <grant.likely@...aro.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC part2 PATCH 2/9] ARM64 / ACPI: Prefill cpu possible/present
 maps and map logical cpu id to APIC id

On Wed, Dec 4, 2013 at 8:21 AM, Hanjun Guo <hanjun.guo@...aro.org> wrote:
> On 2013年12月04日 00:57, One Thousand Gnomes wrote:
>>>
>>> diff --git a/drivers/acpi/plat/arm-core.c b/drivers/acpi/plat/arm-core.c
>>> index 45ff625..8527ecc 100644
>>> --- a/drivers/acpi/plat/arm-core.c
>>> +++ b/drivers/acpi/plat/arm-core.c
>>> @@ -58,6 +58,13 @@ EXPORT_SYMBOL(acpi_pci_disabled);
>>>    */
>>>   static u64 acpi_lapic_addr __initdata;
>>>   +/* available_cpus here means enabled cpu in MADT */
>>> +int available_cpus;
>>> +
>>> +/* Map logic cpu id to physical GIC id. */
>>> +int arm_cpu_to_apicid[NR_CPUS] = { [0 ... NR_CPUS-1] = -1 };
>>> +int boot_cpu_apic_id = -1;
>>> +
>>
>> static ?
>>
>> Really shouldn't be leaking names like "available_cpus" out of ACPI into
>> the global namespace
>
>
> Ok, will update in next version.
>
>
>
>>> +#ifdef CONFIG_SMP
>>> +       if (available_cpus == 0) {
>>> +               pr_info(PREFIX "Found 0 CPUs; assuming 1\n");
>>> +               /* FIXME: should be the real GIC id read from hardware */
>>> +               arm_cpu_to_apicid[available_cpus] = 0;
>>> +               available_cpus = 1;     /* We've got at least one of
>>> these */
>>> +       }
>>> +#endif
>>
>> Isn't this true uniprocessor (by definition in fact)
>
>
> This code is intend to handle some buggy firmware I think.

Really? We have production firmware already that we need to
work-around? That's impressive given there is no production h/w.

Rob
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