[U-Boot] [PATCH] core: of_addr: Correct the size type of of_get_address to fdt_size_t

Eugeniu Rosca erosca at de.adit-jv.com
Mon Aug 26 17:16:09 UTC 2019

Hi Keerthy,
Hi Simon,
cc: Tom

On Tue, Aug 20, 2019 at 09:39:32AM +0530, Keerthy wrote:
> On 19/08/19 3:54 PM, Eugeniu Rosca wrote:
> > I took some time to also review the changes in addition to testing.
> > 
> > I can see that, since its inception in Linux [1], of_get_address() used
> > 'u64*' type for its 'size' argument. That's still valid in v5.3-rc5.
> > So, it looks to me that with this patch we diverge from Linux.
> > 
> > I would barely think that the ASAN issue being fixed in this patch
> > exists in Linux, since the latter receives much more KASAN-enabled
> > testing on regular basis.
> > 
> > Do you foresee any alternative fix w/o diverging from Linux?
> I am afraid No but isn't fdt_size_t also right type to represent size?

'fdt_size_t' is a U-Boot-ism, i.e. it exists nowhere else but in U-Boot.
Just for the record, it appears to be added by Simon's v2013.04 commit
4397a2a80baef ("fdt: Add fdtdec_get_addr_size() to read reg properties")

IMHO injecting a U-Boot-specific data type into the prototype of a
Linux-backported function has below major drawbacks:

 - It is a non-upstream-able solution. Linux will unlikely accept
   'fdt_size_t' as a new type simply b/c Linux OF code existed over
   a decade and it didn't need this type so far.
 - Mutilating Linux upstream code will make further U-Boot backports
   painful, time consuming and error-prone.

Are we on the same page here?

> > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=22ae782f86b7
> > 

Best Regards,

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