Resize of ath79 / ZyXEL NBG6716 kernel partition

[Andre Valentin]

Hi!
Am 23.05.21 um 11:05 schrieb Adrian Schmutzler:
> Hi,
> 
>> -----Original Message-----
>> From: Andre Valentin [mailto:a.valentin at ddimension.net]
>> Sent: Dienstag, 18. Mai 2021 20:11
>> To: OpenWrt Development List <openwrt-devel at lists.openwrt.org>
>> Subject: Resize of ath79 / ZyXEL NBG6716 kernel partition
>>
>> Hi!
>>
>> The NBG6716 has recently been disabled because of size problems with the
>> kernel partition.
>> I'm thinking about extending it to 8MB, shouldn't be a problem.
> 
> Interesting.
> 
> https://github.com/openwrt/openwrt/commit/5d8ea6d34f9f23d4dfff4ffcac8c9599d842c3a8
> 
> I was not aware that we are > 4 MiB for kernel already. Is there anything special about this device (or probably ath79/nand) that causes bigger kernel?

It's a bit more interesting here. ZyXELs bootloader supports uimage lzma but only with a kernel size < ~4MB uncompressed or so..
The trick now is to use a uncompressed uimage and let now do jffs2 compress the image, which the bootloader supports.
That works, bit is way more unoptimized. This is the reason why we hit that limit earlier here.

Kind regards,

André