linux-kernel - Re: [PATCH v2] x86: Revert E820_PRAM change in e820_end

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Message-ID: <1428414669.31093.153.camel@misato.fc.hp.com>
Date:	Tue, 07 Apr 2015 07:51:09 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	Christoph Hellwig <hch@....de>
Cc:	Boaz Harrosh <boaz@...xistor.com>, mingo@...hat.com, hpa@...or.com,
	tglx@...utronix.de, linux-nvdimm@...1.01.org,
	linux-fsdevel@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org, Yinghai Lu <yinghai@...nel.org>
Subject: Re: [PATCH v2] x86: Revert E820_PRAM change in e820_end_pfn()

On Tue, 2015-04-07 at 09:04 +0200, Christoph Hellwig wrote:
> On Tue, Apr 07, 2015 at 09:36:37AM +0300, Boaz Harrosh wrote:
> > On 04/06/2015 10:00 PM, Toshi Kani wrote:
> > > 'Commit ec776ef6bbe17 ("x86/mm: Add support for the non-standard
> > > protected e820 type")' added E820_PRAM ranges, which do not have
> > > have struct-page.  Therefore, there is no need to update max_pfn
> > > to cover the E820_PRAM ranges.  
> > 
> > But E820_PRAM ranges will have the possibility for struct-page.
> > 
> > That said I have tested with this patch +  struct-page and
> 
> I'd love to resurrect the old "real page backed" pmem support from
> the old Intel patches eventually, but with all the arguments on
> how we should do I/O on pmem I'd like to keep that a ѕeparate
> discussion. And leaving only fragments of some support in is a bad
> idea, 

Agreed -- it should be a separate discussion and we need to get it
straight for 4.1.

> so sorry for letting all this slip through..

No problem.

> > > -static unsigned long __init e820_end_pfn(unsigned long limit_pfn)
> > > +static unsigned long __init e820_end_pfn(unsigned long limit_pfn, unsigned type)
> > 
> > Why don't you rename it to say e820_max_ram_pfn or something with ram
> > as you noted, and drop the @type. As Christoph said it is very ugly. You do not
> > put an extra parameter because of a bad name?
> > 
> > Anyway you are changing all call sites so it will not even be a bigger
> > change
> 
> It's a static function, and we have much worse naming sins in public
> ones, so I'm not worried about a _ram more or less.  But if people feel
> stronly about it I'm fine with adding the _ram.
> 
> I feel pretty stronly against adding back a pointless argument, though.

We should keep this patch as a revert/fix, and should not combine with
other cleanup.  Adding the _ram, etc. can be done as a separate change.

Thanks,
-Toshi

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