[PATCH 0/8] Convert Netgear WNR854T to devicetree

[kaloz@openwrt.org (Imre Kaloz)]

On Fri, 26 Aug 2016 18:50:33 +0200, Jamie Lentin <jm@lentin.co.uk> wrote:

> On Fri, 26 Aug 2016, Andrew Lunn wrote:
>
>>>> - the factory layout gives you almost no space to play with
>>
>> Given that the kernel has grown in size over the years, does the
>> mainline kernel fit in the factory layout?
>
> The factory layout has a 6MB JFFS2 for root & uImage (uboot mounts it by  
> default) + 1MB miscellany. So the main restriction on kernel size is the  
> size of your userland.
>
> The non-DT mainline layout is 1MB JFFS2 for uImage + 7MB rootfs. Which  
> is a closer approximation to other devices with a uImage in it's own  
> partition.
>
>>> Of course, one could also argue I'm breaking backwards compatibility
>>> at this point by changing it, so maybe I should put it back.
>>
>> I don't mind breaking backwards compatibility, if the factory defaults
>> no longer actually work.....
>>
>> Also, lets think about the users here. This is a very old box. Anybody
>> playing with one are probably of the sort who tinker with a classic
>> car in the garage, taking the engine apart and putting it back
>> together again. I doubt there are users of this box who take their car
>> in for a service once they are out of windscreen washing water.
>
> My line of thinking was that the only people that will see this default  
> partition scheme are people that have just compiled a mainline kernel  
> and booted it to see what happens. At which point you probably still  
> have the Netgear image in Flash. If you had OpenWRT in Flash then in all  
> likelihood you'd already be using an OpenWRT kernel too, with it's own  
> flash layout. Finally, you could have rolled your own userland and put  
> that on Flash, but by then you should know enough to do what you like :)

Well, that means you have serial console - otherwise without userland it's  
pretty unusable ;) Anyways, I would stay with a modified version of the  
non-DT partitions, with the kernel size increased to ~1.4MB (didn't check  
how much overhead is DT support).


Imre