Where to put a large bootloader-supplied device tree on ARM ?

[David VomLehn (dvomlehn)]

The kernel *must* go where it is linked, but the FDT contains only relative
references and is thus free to go anywhere. The same is true of ramdisks, which
are usually placed after the kernel. How about doing the same with your FDT?

> -----Original Message-----
> From: devicetree-discuss [mailto:devicetree-discuss-
> bounces+dvomlehn=cisco.com at lists.ozlabs.org] On Behalf Of Mitch Bradley
> Sent: Friday, July 06, 2012 5:25 PM
> To: linux-arm-kernel at lists.infradead.org; devicetree-
> discuss at lists.ozlabs.org
> Subject: Where to put a large bootloader-supplied device tree on ARM ?
> 
> I'm passing a flatted device tree from OLPC's bootloader (which
> is a full Open Firmware implementation) to the kernel.  If I
> put the FDT at the "traditional" address 0x100, bad things
> happen when the DT is larger than 16K.  The FDT extends past
> the 0x4000 boundary and gets overwritten by the early page tables
> which are written at that address.
> 
> I have found various places in memory where I can place it
> without it being overwritten, and things work, but that seems
> dodgy and likely to break randomly.
> 
> Has there been any discussion about where large-ish FDT images
> should be located?
> 
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