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From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Cc: Andrew Lunn <andrew@lunn.ch>, Lior Amsalem <alior@marvell.com>,
	Ike Pan <ike.pan@canonical.com>,
	Nadav Haklai <nadavh@marvell.com>,
	David Marlin <dmarlin@redhat.com>,
	Yehuda Yitschak <yehuday@marvell.com>,
	Tawfik Bayouk <tawfik@marvell.com>,
	Dan Frazier <dann.frazier@canonical.com>,
	Eran Ben-Avi <benavi@marvell.com>,
	Ezequiel Garcia <ezequiel.garcia@free-electrons.com>,
	Leif Lindholm <leif.lindholm@arm.com>,
	Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
	Jason Cooper <jason@lakedaemon.net>,
	Arnd Bergmann <arnd@arndb.de>, Jon Masters <jcm@redhat.com>,
	devicetree-discuss@lists.ozlabs.org,
	Rob Herring <rob.herring@calxeda.com>,
	Gregory CLEMENT <gregory.clement@free-electrons.com>,
	linux-arm-kernel@lists.infradead.org,
	Chris Van Hoof <vanhoof@canonical.com>,
	Nicolas Pitre <nico@fluxnic.net>,
	linux-kernel@vger.kernel.org,
	Grant Likely <grant.likely@secretlab.c>
Subject: Re: [PATCH 5/5] arm: dts: Convert mvebu device tree files to 64 bits
Date: Thu, 21 Mar 2013 22:15:23 +0100	[thread overview]
Message-ID: <20130321221523.7ede6ccc@skate> (raw)
In-Reply-To: <20130321205545.GA8358@obsidianresearch.com>

Dear Jason Gunthorpe,

On Thu, 21 Mar 2013 14:55:45 -0600, Jason Gunthorpe wrote:

> Or, better, locate all the internal registers above 8G and use
> contiguous DRAM mapping from 0 -> 8GB

I see two potential issues with this idea:

 *) It only works when LPAE is enabled, so we would have to have
    different internal register addresses depending on whether LPAE is
    enabled or not. Probably not impossible, but not very
    straightforward either.

 *) It would require Linux to change the internal registers address
    (for now the kernel relies on the bootloader). The problem is that
    we can't do it early enough to preserve the earlyprintk
    functionality. Maybe you have suggestions on how to achieve that?

Best regards,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

  reply	other threads:[~2013-03-21 21:15 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-21 16:26 [PATCH 0/5] arm: mvebu: Enable LPAE support for Armada XP SoCs Gregory CLEMENT
     [not found] ` <1363883179-1361-1-git-send-email-gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2013-03-21 16:26   ` [PATCH 1/5] arm: mvebu: Aligne the internal registers virtual base to support LPAE Gregory CLEMENT
2013-03-21 16:26 ` [PATCH 2/5] arm: mvebu: Select DMA_BOUNCE when LPAE is selected in Kconfig Gregory CLEMENT
2013-03-21 18:19   ` Rob Herring
2013-03-21 19:18   ` Andrew Lunn
     [not found]   ` <1363883179-1361-3-git-send-email-gregory.clement-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2013-03-22 11:32     ` Russell King - ARM Linux
     [not found]       ` <20130322113251.GB4977-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2013-03-23 19:48         ` Krzysztof Halasa
2013-03-21 16:26 ` [PATCH 3/5] arm: mvebu: Enable pj4b on LPAE compilations Gregory CLEMENT
2013-03-21 16:26 ` [PATCH 4/5] arm: dts: Add a 64 bits version of the skeleton device tree Gregory CLEMENT
2013-03-21 16:26 ` [PATCH 5/5] arm: dts: Convert mvebu device tree files to 64 bits Gregory CLEMENT
2013-03-21 17:59   ` Rob Herring
     [not found]     ` <514B4A79.1070501-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2013-03-21 19:03       ` Arnd Bergmann
2013-03-21 19:18         ` Thomas Petazzoni
2013-03-21 21:31           ` Arnd Bergmann
     [not found]             ` <201303212131.07629.arnd-r2nGTMty4D4@public.gmane.org>
2013-03-21 22:30               ` Sebastian Hesselbarth
2013-03-21 20:15   ` Andrew Lunn
2013-03-21 20:22     ` Thomas Petazzoni
2013-03-21 20:30       ` Jason Cooper
2013-03-21 20:37       ` Andrew Lunn
2013-03-21 21:08         ` Thomas Petazzoni
2013-03-21 21:16         ` Thomas Petazzoni
2013-03-21 20:55       ` Jason Gunthorpe
2013-03-21 21:15         ` Thomas Petazzoni [this message]
2013-03-21 21:35           ` Lior Amsalem
     [not found]             ` <EE71107DF0D1F24FA2D95041E64AB9E801A56C7B6D24-YTFUtKQQMWV5iqk/IoNZdEEOCMrvLtNR@public.gmane.org>
2013-03-21 21:46               ` Jason Gunthorpe
     [not found]                 ` <20130321214607.GC8431-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2013-03-21 21:58                   ` Lior Amsalem
     [not found]                     ` <EE71107DF0D1F24FA2D95041E64AB9E801A56C7B6D25-YTFUtKQQMWV5iqk/IoNZdEEOCMrvLtNR@public.gmane.org>
2013-03-22  6:55                       ` Arnd Bergmann
2013-03-21 21:41           ` Jason Gunthorpe
2013-03-21 22:26             ` Sebastian Hesselbarth
2013-03-22  9:55             ` Arnd Bergmann
     [not found]         ` <20130321205545.GA8358-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2013-03-21 21:25           ` Andrew Lunn
2013-03-22  6:28           ` Andrew Lunn
     [not found]             ` <20130322062854.GS21478-g2DYL2Zd6BY@public.gmane.org>
2013-03-22 17:43               ` Jason Gunthorpe
     [not found]                 ` <20130322174300.GA10230-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2013-03-22 19:33                   ` Arnd Bergmann

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