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From: Mark Rutland <mark.rutland@arm.com>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>,
	"Elliott, Robert (Persistent Memory)" <elliott@hpe.com>,
	"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"will.deacon@arm.com" <will.deacon@arm.com>,
	"matt@codeblueprint.co.uk" <matt@codeblueprint.co.uk>,
	"dan.j.williams@intel.com" <dan.j.williams@intel.com>,
	"Kani, Toshimitsu" <toshi.kani@hpe.com>,
	"Knippers, Linda" <linda.knippers@hpe.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Matthew Wilcox <willy@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Theodore Ts'o <tytso@mit.edu>
Subject: Re: arm64/efi handling of persistent memory
Date: Wed, 20 Jan 2016 14:23:32 +0000	[thread overview]
Message-ID: <20160120142330.GA28169@leverpostej> (raw)
In-Reply-To: <CAKv+Gu_KEDMdeF5zWL6EEwJyo+kt0u6HeaqrcVOEP9YHeu7uuw@mail.gmail.com>

Hi,

For those newly Cc'd, the initially reported problem is that arm64 Linux
currently treats persistent memory as with any other memory (happily clobbering
it), per [1].

On Fri, Dec 18, 2015 at 02:07:10PM +0100, Ard Biesheuvel wrote:
> Before we start hacking away at this at the arm64/EFI level, do we
> have any documentation and/or consensus regarding how persistent
> memory should be treated in the first place? Should it be covered by
> memblock? Should it be covered by the linear mapping? Should it be
> memblock_reserve()'d?

I'm hoping that the lack of replies has more to do with the recent
holiday than a lack of opinion...

I think that it's sensible to say that at minimum we need to ensure that we
don't treat it as available RAM (i.e. we don't clobber it with random data) for
now.

Per [2] it's not clear to me what the consensus is on memblock, the linear
mapping, and the use of struct page, though that's months old so perhaps that's
been figured out since. I've Cc'd some of the attendees in case they can
clarify the situation.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-December/394707.html
[2] https://lwn.net/Articles/636096/

Thanks,
Mark.

WARNING: multiple messages have this Message-ID (diff)
From: Mark Rutland <mark.rutland@arm.com>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>,
	"Elliott, Robert (Persistent Memory)" <elliott@hpe.com>,
	"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"will.deacon@arm.com" <will.deacon@arm.com>,
	"matt@codeblueprint.co.uk" <matt@codeblueprint.co.uk>,
	"dan.j.williams@intel.com" <dan.j.williams@intel.com>,
	"Kani, Toshimitsu" <toshi.kani@hpe.com>,
	"Knippers, Linda" <linda.knippers@hpe.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-nvdimm@lists.01.org" <linux-nvdimm@ml01.01.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Matthew Wilcox <willy@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"Theodore Ts'o" <tytso@mit.edu>
Subject: Re: arm64/efi handling of persistent memory
Date: Wed, 20 Jan 2016 14:23:32 +0000	[thread overview]
Message-ID: <20160120142330.GA28169@leverpostej> (raw)
In-Reply-To: <CAKv+Gu_KEDMdeF5zWL6EEwJyo+kt0u6HeaqrcVOEP9YHeu7uuw@mail.gmail.com>

Hi,

For those newly Cc'd, the initially reported problem is that arm64 Linux
currently treats persistent memory as with any other memory (happily clobbering
it), per [1].

On Fri, Dec 18, 2015 at 02:07:10PM +0100, Ard Biesheuvel wrote:
> Before we start hacking away at this at the arm64/EFI level, do we
> have any documentation and/or consensus regarding how persistent
> memory should be treated in the first place? Should it be covered by
> memblock? Should it be covered by the linear mapping? Should it be
> memblock_reserve()'d?

I'm hoping that the lack of replies has more to do with the recent
holiday than a lack of opinion...

I think that it's sensible to say that at minimum we need to ensure that we
don't treat it as available RAM (i.e. we don't clobber it with random data) for
now.

Per [2] it's not clear to me what the consensus is on memblock, the linear
mapping, and the use of struct page, though that's months old so perhaps that's
been figured out since. I've Cc'd some of the attendees in case they can
clarify the situation.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-December/394707.html
[2] https://lwn.net/Articles/636096/

Thanks,
Mark.

WARNING: multiple messages have this Message-ID (diff)
From: mark.rutland@arm.com (Mark Rutland)
To: linux-arm-kernel@lists.infradead.org
Subject: arm64/efi handling of persistent memory
Date: Wed, 20 Jan 2016 14:23:32 +0000	[thread overview]
Message-ID: <20160120142330.GA28169@leverpostej> (raw)
In-Reply-To: <CAKv+Gu_KEDMdeF5zWL6EEwJyo+kt0u6HeaqrcVOEP9YHeu7uuw@mail.gmail.com>

Hi,

For those newly Cc'd, the initially reported problem is that arm64 Linux
currently treats persistent memory as with any other memory (happily clobbering
it), per [1].

On Fri, Dec 18, 2015 at 02:07:10PM +0100, Ard Biesheuvel wrote:
> Before we start hacking away at this at the arm64/EFI level, do we
> have any documentation and/or consensus regarding how persistent
> memory should be treated in the first place? Should it be covered by
> memblock? Should it be covered by the linear mapping? Should it be
> memblock_reserve()'d?

I'm hoping that the lack of replies has more to do with the recent
holiday than a lack of opinion...

I think that it's sensible to say that at minimum we need to ensure that we
don't treat it as available RAM (i.e. we don't clobber it with random data) for
now.

Per [2] it's not clear to me what the consensus is on memblock, the linear
mapping, and the use of struct page, though that's months old so perhaps that's
been figured out since. I've Cc'd some of the attendees in case they can
clarify the situation.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-December/394707.html
[2] https://lwn.net/Articles/636096/

Thanks,
Mark.

  reply	other threads:[~2016-01-20 14:23 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-18  1:33 arm64/efi handling of persistent memory Elliott, Robert (Persistent Memory)
2015-12-18  1:33 ` Elliott, Robert (Persistent Memory)
2015-12-18  1:33 ` Elliott, Robert (Persistent Memory)
2015-12-18 11:06 ` Leif Lindholm
2015-12-18 11:06   ` Leif Lindholm
2015-12-18 11:06   ` Leif Lindholm
2015-12-18 11:45   ` Mark Rutland
2015-12-18 11:45     ` Mark Rutland
2015-12-18 11:45     ` Mark Rutland
2015-12-18 13:07     ` Ard Biesheuvel
2015-12-18 13:07       ` Ard Biesheuvel
2015-12-18 13:07       ` Ard Biesheuvel
2016-01-20 14:23       ` Mark Rutland [this message]
2016-01-20 14:23         ` Mark Rutland
2016-01-20 14:23         ` Mark Rutland
2015-12-18 11:52   ` Mark Rutland
2015-12-18 11:52     ` Mark Rutland
2015-12-18 11:52     ` Mark Rutland
2015-12-18 12:11     ` Leif Lindholm
2015-12-18 12:11       ` Leif Lindholm
2015-12-18 12:11       ` Leif Lindholm
2015-12-18 13:27     ` Matt Fleming
2015-12-18 13:27       ` Matt Fleming
2015-12-18 13:27       ` Matt Fleming

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