[U-Boot] 64Bit device tree compilation

[Thierry Reding]

On Thu, Mar 19, 2015 at 07:43:35AM -0600, Simon Glass wrote:
> Hi Hanna,
> 
> On 18 March 2015 at 11:17, Hanna Hawa <hannah at marvell.com> wrote:
> > Hi Simon,
> >
> >
> >
> > My name is Hanna, I’m working in Software team in Marvell with Yehuda.
> >
> >
> >
> > I’m trying to run U-Boot with FDT in 64Bit.
> >
> > I’ve issue when I’m trying to load the image on my board, I got abort
> > (**Synchronous Abort**)
> >
> > Exactly when the U-boot run fdt_addr_to_cpu(*cell) under lib/fdtdec.c
> >
> >
> >
> > The issue is the format of the FDT is 32Bit, and Big Endian mode.
> >
> >
> >
> > After some debug, I changed the typedef of fdt_size, and fdt_addr to be u32.
> >
> > Also fdt_addr_to_cpu, and fdt_size_to_cpu  to use u32 swap, it works.
> >
> >
> >
> > My question is:
> >
> > Is that correct to change the typedef to use u32Bit?
> 
> What do you have CONFIG_PHYS_64BIT set to? That is supposed to
> indicate the machine word size. Do you have a 64-bit CPU?
> 
> I recall someone reporting that on 64-bit machines things like '*cell'
> can fail because the address is not always 64-bit aligned. But on
> 64-bit machines, fdt_addr_t should be 64-bit, so changing it to 32-bit
> seems wrong since you may not be able to address everything (e.g. the
> reg properties will be limited to the first 4GB).
> 
> I suspect it is wrong to use *cell. Instead we could use
> fdtdec_get_number(cell, <size>) or similar logic. Any existing use of
> fdt_addr_t/fdt_size_t to access a cell is wrong, i.e. in
> fdtdec_get_addr_size() and fdtdec_decode_region(). You could send a
> patch for that.

I have a couple of patches for this kind of issue that I encountered
during recent bring-up of 64-bit U-Boot on Tegra210. I'm on my way out
of the office right now, but I'll send out the patches tomorrow.

Thierry
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