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Date: Wed, 13 Jun 2012 13:25:53 -0500
From: Nathan Whitehorn <nwhitehorn@freebsd.org>
Subject: Re: [Cbe-oss-dev] [PATCH 05/10] powerpc/ps3: Use highmem region from
 repository
In-reply-to: <1339610324.3986.6.camel@clam>
To: Geoff Levand <geoff@infradead.org>
Message-id: <4FD8DB31.6080207@freebsd.org>
References: <cover.1335379330.git.geoff@infradead.org>
 <1e755c09926de2d9b0e239ba0ce10fdb6835551a.1335379330.git.geoff@infradead.org>
 <1339552163.25512.2.camel@concordia> <1339610324.3986.6.camel@clam>
Cc: cbe-oss-dev@lists.ozlabs.org, Andre Heider <a.heider@gmail.com>,
 Hector Martin <hector@marcansoft.com>, linuxppc-dev@lists.ozlabs.org
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On 06/13/12 12:58, Geoff Levand wrote:
> Hi Michael,
>
> On Wed, 2012-06-13 at 11:49 +1000, Michael Ellerman wrote:
>> On Wed, 2012-04-25 at 19:19 +0000, Andre Heider wrote:
>>> Use any preallocated highmem region setup by the bootloader.
>>> This implementation only checks for the existance of a single
>>> region at region_index=0.
>>>
>>> This feature allows the bootloader to preallocate highmem
>>> regions and pass the region locations to the kernel through
>>> the repository.  Preallocated regions can be used to hold the
>>> initrd or other large data.  If no region info exists, the
>>> kernel retains the old behavior and attempts to allocate the
>>> highmem region itself.
>>>
>>> Based on Hector Martin's patch "Get lv1 high memory region from
>>> devtree".
>> Apologies if this has been covered before, but why not use the device
>> tree?
> FreeBSD (and other OS's) don't know about the Linux device tree.
>
> This mechanism is for the bootloader to tell the OS about a highmem
> region it setup, and we want to support more than just Linux.
>
> -Geoff
>
>
FreeBSD actually does have FDT support -- it's just not used for the PS3 
platform at the moment since it is (currently) totally redundant with 
the HV repository. If people decide that FDT has an advantage, FreeBSD 
at least can easily be adapted to use it.
-Nathan