[U-Boot] 64Bit device tree compilation

[Simon Glass]

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.

Regards,
Simon