linux-kernel - Re: [PATCH 2/2] x86,mm,64bit: Round up memory boundary for init_memory_mapping

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Date:	Fri, 25 Feb 2011 12:22:15 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Tejun Heo <tj@...nel.org>, Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] x86,mm,64bit: Round up memory boundary for init_memory_mapping_high()

On 02/25/2011 02:03 AM, Ingo Molnar wrote:
> 
> * Yinghai Lu <yinghai@...nel.org> wrote:
> 
>>  init_memory_mapping_active_regions(unsigned long start, unsigned long end)
>>  {
>>  	struct mapping_work_data data;
>> +	int use_gbpages;
>> +
>> +	/* see init_memory_mapping() for the setting */
>> +#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK)
>> +	use_gbpages = 0;
>> +#else
>> +	use_gbpages = direct_gbpages;
>> +#endif
> 
> Sigh. You should *never* ever even think about writing such code. It only results in 
> crap, and in crap duplicated elsewhere as well:
> 
> if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK)
>         /*
>          * For CONFIG_DEBUG_PAGEALLOC, identity mapping will use small pages.
>          * This will simplify cpa(), which otherwise needs to support splitting
>          * large pages into small in interrupt context, etc.
>          */
>         use_pse = use_gbpages = 0;
> #else
>         use_pse = cpu_has_pse;
>         use_gbpages = direct_gbpages;
> #endif

sorry, actually i copied from there.

or i could add max_map_unit_size variable?

Thanks

Yinghai


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