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From: "Jayachandran C." <jchandra@freebsd.org>
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Cc: Rafal Jaworowski <raj@semihalf.com>, Marcel Moolenaar <marcel@freebsd.org>,
	FreeBSD Current <freebsd-current@freebsd.org>
Subject: Re: [RFC] FDT fix for 64 bit platforms
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On Sat, Oct 15, 2011 at 2:01 AM, Nathan Whitehorn
<nwhitehorn@freebsd.org> wrote:
> On 10/14/11 14:10, Jayachandran C. wrote:
>>
>> I'm planning commit this -CURRENT if there an no objections.
>>
>> In the current implementation, phandle is used to store a pointer to
>> the location inside the device tree. =A0Since phandle_t is u32, this
>> will not work on 64 bit platforms. With this fix, the phandle is the
>> offset from the start of device tree pointer 'fdtp', which will be 32
>> bit.
>>
>> Review or testing from device tree users will be welcome.
>>
>> JC.
>
> Why not use offsets into the FDT rather than full pointers? I believe hav=
ing
> phandles greater than 32 bits violates the FDT spec, and declaring that t=
he
> FDT can't itself be larger than 4 GB seems reasonable.

I am actually using the offset from the beginning of FDT (fdtp) as
phandle.  I cannot use the usual fdt offset (after off_dt_struct) as
phandle, because in that case offset of 0 is valid, but phandle 0
should not be valid.

JC.