[OpenWrt-Devel] [PATCH v2 2/4] ramips: fix RBM33G partitioning

[Daniel F. Dickinson]

On 2018-07-30 04:09 AM, Thibaut wrote:
> 
> 
>> Le 30 juil. 2018 à 08:40, John Crispin <john at phrozen.org> a écrit :
>>
>>
>>
>> On 29/07/18 11:07, Thibaut VARÈNE wrote:
>>> This patch improves 5684d087418d176cfdef4e045e1950ca7ba3b09f by correcting
>>> the partition scheme for the "RouterBoot" section of the flash.
>>>
>>> This section is subdivided in several segments, as they are on ar71xx
>>> RB devices, albeit with different offsets and sizes. The naming convention
>>> from ar71xx has been preserved. The preferred 'fixed-partitions' DTS
>>> node syntax is used, with nesting support as introduced in 2a598bbaa3.
>>>
>>> The OEM source code also define a "RouterBootFake" partition at the
>>> beginning of the secondary flash chip: to avoid trouble if OEM ever makes
>>> use of that space, it is also defined here.
>>
>> as discussed on IRC we concluded, that this should be done with a mtd splitter.
>>     John
> 
> I’m sorry, we didn’t conclude anything, I believe you demanded it be done so.
> 
> Unfortunately, after a more careful investigation, I am now convinced this is not the right course of action. Here’s why, in my very humble opinion and limited understanding:
> 
> - this splitter will be quite intrusive in generic code (currently « mtdsplit » only works with « firmware » and « rootfs » named partitions)
> - the bootloaders (routerboot and routerboot2) cannot be programmatically splitted: they are raw machine code without a signature
> - all ramips routerboard machines share the exact same partition scheme which is different from all the ar71xx routerboard machines (which also all share the same scheme)
> - if I read the OEM source code correctly, it’s likely their ARM-based boards have yet another partition scheme
> 
> Consequently, a purported splitter will be invasive and full of hardcoded numbers, making its upstream acceptance very unlikely (I anticipate the argument « this should all be done in DTS, especially now that DTS supports nested partitions »).
> 
> Now, I would like to hope that a correct partition scheme that uses all the OpenWRT-accepted features and follows guidelines would be more likely to be accepted in the source than the currently broken, incorrect and incomplete existing one.
> 

I'm not sure but I think
https://github.com/openwrt/openwrt/commit/2a598bbaa3f75b7051c2453a6ccf706191cf2153
(kernel: backport mtd support for subpartitions in DT) might be of use
here...

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