[OpenWrt-Devel] ipq40xx: Bogus IMAGE_SIZE on asus rt-ac58u

Christian Lamparter chunkeey at gmail.com
Fri Nov 8 13:46:01 EST 2019


On Tuesday, November 5, 2019 8:13:59 PM CET Adrian Schmutzler wrote:
> as stated already in the comment of an earlier patch, the asus_rt-ac58u
> on ipq40xx target has an IMAGE_SIZE of 20439364, which cannot be divided
> by 1024 and also does not seem to match anything in DTS.

This was soo long ago, but luckily I kept some notes and files in the cold
storage... and since it's finally snowing outside, they became accessible.

As for the relying on the DTS: Please don't in this case. The RT-AC58U uses
UBI. So multiple volumes are stored in that UBI_DEV (or "ubi" now) partition.
The original u-boot from ASUS kept a failsafe volume around so does works   

> I couldn't identify what should be the correct value in this case,
> so maybe someone more familiar with the target could have a look and fix this odd value.

It was the size of the original firmware back in 2016.

You should be able to confirm this, just download the firmware called:
"FW_RT_AC58U_30043806516.zip" and extract it.
In the archive, there should be this file (ls -al ouput):
"-rw-r--r-- 1 user user 20439364 Oct  4  2016 FW_RT-AC58U_3.0.0.4_380_6516-g6772678.trx"

This is where the IMAGE_SIZE was coming from. From what I can tell,
the firmware web upgrade had issues with the full ~48MiB image size,
so I opted to 1:1 copy the size of that firmware file to be on the
safe side. (The tftp method didn't have that limitation though).

And finally: The RT-AC58U is in a bit of a dicy pickle (together with other
some ath79 devices).  Reason being that due to the poor memory management of
wifi drivers, the 128 MiB of RAM it has is not enough. When the wifis are
activated and pushed the device runs into OOMs and regulary crashes/panics.
So in a way, it's on the chopping block.

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