linux-kernel - Re: [Linaro-acpi] [PATCH 04/20] ARM64 / ACPI: Introduce arm_core.c and its related head file

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Date:	Thu, 23 Jan 2014 16:56:44 +0100
From:	Tomasz Nowicki <tomasz.nowicki@...aro.org>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Hanjun Guo <hanjun.guo@...aro.org>
CC:	Matthew Garrett <mjg59@...f.ucam.org>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>, Rob Herring <robh@...nel.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Olof Johansson <olof@...om.net>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Will Deacon <Will.Deacon@....com>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"patches@...aro.org" <patches@...aro.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [Linaro-acpi] [PATCH 04/20] ARM64 / ACPI: Introduce arm_core.c
 and its related head file

Hi Lorenzo,

W dniu 22.01.2014 12:54, Lorenzo Pieralisi pisze:
> On Fri, Jan 17, 2014 at 12:24:58PM +0000, Hanjun Guo wrote:
>
> [...]
>
>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
>> index bd9bbd0..2210353 100644
>> --- a/arch/arm64/kernel/setup.c
>> +++ b/arch/arm64/kernel/setup.c
>> @@ -41,6 +41,7 @@
>>   #include <linux/memblock.h>
>>   #include <linux/of_fdt.h>
>>   #include <linux/of_platform.h>
>> +#include <linux/acpi.h>
>>
>>   #include <asm/cputype.h>
>>   #include <asm/elf.h>
>> @@ -225,6 +226,11 @@ void __init setup_arch(char **cmdline_p)
>>
>>   	arm64_memblock_init();
>>
>> +	/* Parse the ACPI tables for possible boot-time configuration */
>> +	acpi_boot_table_init();
>> +	early_acpi_boot_init();
>> +	acpi_boot_init();
>> +
>>   	paging_init();
>
> Can I ask you please why we need to parse ACPI tables before
> paging_init() ?
This is for future usage and because of couple of reasons. Mainly SRAT 
table parsing should be done (before paging_init()) for proper NUMA 
initialization and then paging_init().

Regards,
Tomasz
>
> [...]
>
>> +/*
>> + * __acpi_map_table() will be called before page_init(), so early_ioremap()
>> + * or early_memremap() should be called here.
>
> Again, why is this needed ? What's needed before paging_init() from ACPI ?
>
> [...]
>
>> +/*
>> + * acpi_boot_table_init() and acpi_boot_init()
>> + *  called from setup_arch(), always.
>> + *	1. checksums all tables
>> + *	2. enumerates lapics
>> + *	3. enumerates io-apics
>> + *
>> + * acpi_table_init() is separated to allow reading SRAT without
>> + * other side effects.
>> + */
>> +void __init acpi_boot_table_init(void)
>> +{
>> +	/*
>> +	 * If acpi_disabled, bail out
>> +	 */
>> +	if (acpi_disabled)
>> +		return;
>> +
>> +	/*
>> +	 * Initialize the ACPI boot-time table parser.
>> +	 */
>> +	if (acpi_table_init()) {
>> +		disable_acpi();
>> +		return;
>> +	}
>> +}
>> +
>> +int __init early_acpi_boot_init(void)
>> +{
>> +	/*
>> +	 * If acpi_disabled, bail out
>> +	 */
>> +	if (acpi_disabled)
>> +		return -ENODEV;
>> +
>> +	/*
>> +	 * Process the Multiple APIC Description Table (MADT), if present
>> +	 */
>> +	early_acpi_process_madt();
>> +
>> +	return 0;
>> +}
>> +
>> +int __init acpi_boot_init(void)
>> +{
>> +	/*
>> +	 * If acpi_disabled, bail out
>> +	 */
>> +	if (acpi_disabled)
>> +		return -ENODEV;
>> +
>> +	acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt);
>> +
>> +	/*
>> +	 * Process the Multiple APIC Description Table (MADT), if present
>> +	 */
>> +	acpi_process_madt();
>> +
>> +	return 0;
>> +}
>
> Well, apart from having three init calls, one returning void and two
> returning proper values, do not understand why, and do not understand
> why we need three calls in the first place...why should we process MADT
> twice in two separate calls ? What is supposed to change in between that
> prevents you from merging the two together ?
>
> Thanks,
> Lorenzo
>
>
> _______________________________________________
> Linaro-acpi mailing list
> Linaro-acpi@...ts.linaro.org
> http://lists.linaro.org/mailman/listinfo/linaro-acpi
>
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