Hi,
On 12/12/17 04:50, Masahiro Yamada wrote:
> Hi Simon,
>
>
> 2017-12-12 13:38 GMT+09:00 Simon Glass <s...@chromium.org>:
>> Hi Andre,
>>
>> On 3 December 2017 at 19:05, Andre Przywara <andre.przyw...@arm.com> wrote:
>>> The DT spec[1] demands a unit-address in a node name (name@address) to
>>> match the "reg" property inside that node:
>>> uart0: serial@1c28000 {
>>> reg = <0x01c28000 0x400>;
>>> ....
>>> If there is no reg property in a node, there must not be a unit address
>>> in the node name as well (so no '@' sign at all).
>>>
>>> Newer version of the device tree compiler (dtc) will warn about violations
>>> of this rule:
>>> ....
>>> <stdout>: Warning (unit_address_vs_reg): Node /images/fdt@1 has a unit name,
>>> but no reg property
>>> ....
>>>
>>> To avoid those warnings, but still keep enumerable node names, we replace
>>> the "@" sign with a dash ("-"), which does not have a specical meaning,
>>> but is a valid node name character. So the first fdt file (as referenced
>>> above in the warning message) would be called "fdt-1" instead.
>>>
>>> This affects mostly documenation files and some examples of FIT image
>>> files, but also some code which actually generates FIT images:
>>> - The first four patches fix documentation, example files and comments,
>>> they should not affect actual generated code or files.
>>> In places where having multiple instances of a node is normal (fdt,
>>> hash, signature), I simply replaced the '@' sign with the dash.
>>> Where one would expect only one instance (kernel, initrd), I removed the
>>> bogus '@1' completely, so a "kernel" just goes by just this very name.
>>> - Patch 5/7 fixes the usage in the Allwinner SPL FIT image files, this has
>>> been on the list before.
>>> - Patch 6/7 fixes the usage when the mkimage tool (auto-)generates FIT
>>> images.
>>> - The final patch 7/7 fixes the usage for the ARMv8 secure firmware image
>>> handling. I am a bit unsure about this one, as this seems to *look* for
>>> a specific node name, which sounds a bit dodgy to me. I think DT parsers
>>> should never rely on a certain node name, but either use references or look
>>> inside nodes to find a matching one. Also I am not sure who actually
>>> generates those FIT image files this code gets to read. Any input would
>>> be welcome here.
>>>
>>> Please let me know if this makes some sense or not.
>>
>> I thought I read somewhere that there is a dtc option to turn off
>> these warnings?
>>
>
> I think -Wno-unit_address_vs_reg is the one,
> but I prefer to fix the root cause by replacing @
> instead of hiding it.
Yes, I pulled this series off purely because Masahiro asked for it
before. I am just after patch 5/7 ;-)
And I agree with him that we should fix it rather than paper over it -
at least for the code parts. And if we do so, we should fix the
documentation as well - so here we go.
I know it's a pain to review (sorry for that!).
I would appreciate if we could push 5/7 through - as without it I see
warnings right now and I am sure that it works. 6/7 looks good as well,
though I can't say if there are side effects. Normally one would expect
that node names are purely descriptive, but 7/7 tells me otherwise.
Cheers,
Andre.
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