linux-kernel - Re: [Part1 PATCH v5 03/22] x86, ACPI, mm: Kill max_low_pfn

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Message-ID: <CAE9FiQXTAT69WKvzXe7FuuSqiA9epuSGPFP2ihhpDZkqYtn9_g@mail.gmail.com>
Date:	Mon, 17 Jun 2013 14:13:58 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Tejun Heo <tj@...nel.org>
Cc:	Tang Chen <tangchen@...fujitsu.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Renninger <trenn@...e.de>,
	Jiang Liu <jiang.liu@...wei.com>,
	Wen Congyang <wency@...fujitsu.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	Mel Gorman <mgorman@...e.de>, Minchan Kim <minchan@...nel.org>,
	mina86@...a86.com, gong.chen@...ux.intel.com,
	vasilis.liaskovitis@...fitbricks.com, lwoodman@...hat.com,
	Rik van Riel <riel@...hat.com>, jweiner@...hat.com,
	Prarit Bhargava <prarit@...hat.com>,
	"the arch/x86 maintainers" <x86@...nel.org>,
	linux-doc@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux MM <linux-mm@...ck.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Jacob Shin <jacob.shin@....com>,
	Pekka Enberg <penberg@...nel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Subject: Re: [Part1 PATCH v5 03/22] x86, ACPI, mm: Kill max_low_pfn_mapped

On Mon, Jun 17, 2013 at 2:04 PM, Tejun Heo <tj@...nel.org> wrote:
> Hello,
>
> On Thu, Jun 13, 2013 at 09:02:50PM +0800, Tang Chen wrote:
>> From: Yinghai Lu <yinghai@...nel.org>
>>
>> Now we have pfn_mapped[] array, and max_low_pfn_mapped should not
>> be used anymore. Users should use pfn_mapped[] or just
>> 1UL<<(32-PAGE_SHIFT) instead.
>>
>> The only user of max_low_pfn_mapped is ACPI_INITRD_TABLE_OVERRIDE.
>> We could change to use 1U<<(32_PAGE_SHIFT) with it, aka under 4G.
>
>                                 ^ typo

ok.

>
> ...
>> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
>> index e721863..93e3194 100644
>> --- a/drivers/acpi/osl.c
>> +++ b/drivers/acpi/osl.c
>> @@ -624,9 +624,9 @@ void __init acpi_initrd_override(void *data, size_t size)
>>       if (table_nr == 0)
>>               return;
>>
>> -     acpi_tables_addr =
>> -             memblock_find_in_range(0, max_low_pfn_mapped << PAGE_SHIFT,
>> -                                    all_tables_size, PAGE_SIZE);
>> +     /* under 4G at first, then above 4G */
>> +     acpi_tables_addr = memblock_find_in_range(0, (1ULL<<32) - 1,
>> +                                     all_tables_size, PAGE_SIZE);
>
> No bigge, but why (1ULL << 32) - 1?  Shouldn't it be just 1ULL << 32?
> memblock deals with [@start, @end) areas, right?

that is for 32bit, when phys_addr_t is 32bit, in that case
(1ULL<<32) cast to 32bit would be 0.

>
> Other than that,
>
>  Acked-by: Tejun Heo <tj@...nel.org>

Thanks

Yinghai
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