[PATCH] boot: fdt: Turn all addresses and sizes into u64

[Marek Vasut]

On 4/14/24 9:29 PM, Laurent Pinchart wrote:
> Hi Marek,
> 
> Thank you for the patch.
> 
> On Sun, Apr 14, 2024 at 08:37:20PM +0200, Marek Vasut wrote:
>> In case of systems where DRAM bank ends at the edge of 32bit boundary,
>> start + size calculations would overflow. This happens on STM32MP15xx
>> with 1 DRAM bank starting at 0xc0000000 and 1 GiB of DRAM. This is a
>> usual 32bit system DRAM size overflow, fix it by doing all DRAM size
>> and offset calculations using u64 types.
> 
> I'm not sure I like this much, as it removes a useful indication
> regarding what the variables store.

That's what the variable name is for, not variable type.

> Wouldn't it be better if the code's
> logic could be modified to avoid those overflows ?

I'd prefer to keep the code simple and blanket avoid the overflows for a 
very long time, rather than play whack-a-mole with various odd corner 
cases here.

Note that this is a fix for a previous series which changed from 
u64/ulong to phys_addr/size_t , which clearly was incorrect .

>> This also covers a case where
>> a 32bit PAE system might be able to address up to 36bits of DRAM.
> 
> Shouldn't phys_addr_t be a 64-bit type on PAE systems ?

That depends on CONFIG_PHYS_64BIT , on am57xx this is not set for 
example, so there phys_addr_t is 32bit .