256Mb RAM on Asus

OpenWrt 18.06.2 ( r7676-cddd7b4c77 ) doesn't use 256Mb on Asus RT-N66U, it only sees 128Mb.
( 'Found 128 MiB of extra memory, but highmem is unsupported yet!' )

Is there a way to overcome this?

I think this post agrees with you

Noting that this was over 2 years ago, I'd imagine that if this is not solved yet, i's unlikely that it will ever be. This device isn't really attractive, being Broadcom with the issues of lack of opensource drivers and related wireless limitations.


Develop such a support & send a patch :slight_smile:
I don't really have much motivation for that, there are quite a few more important things on my list.

well a lot of devices use broadcom. why don't you just reverse engineer drivers from ddwrt or something?
it should be possible at least?
i lack such skills.

If Broadcom, or any manufacturer for that matter, chooses to not share their drivers or make them easily available, then that's doesn't make the device an attractive target for an open source project that also has to adhere to license(s) terms.

The problem is that drivers available are often built for an older Kernel version. For example, I have Asus RT-AC66U, and the latest stock firmware (that's only 1 year old) is using an ancient Kernel 2.6! Now if, you see, the manufacturer (ASUS, who are the direct client of Broadcom in this case) got only access to Kernel 2.6 drivers, then there must be difficulties.

I have also checked some of Tomato firmware variations, and it appears that most of them stopped at Kernel 2.6 as well. There is Fresh Tomoato that you can check which seems to be still active, but I don't know if they have new drivers or not.

I have asked the question on dd-wrt forum about what Kernel version their recent, and thy might actually support Kernel 3.x. I don't know how they got it, but still it's rather outdated.

That's all about my RT-AC66U. I don't know about RT-N66U or what kernel is OpenWrt is using, but the point I'm trying to make is that with Broadcom not making their drivers open, it's just harder for everybody to work with that. The effort spent in struggling with supporting these devices can be better spent working with many more developer-friendly devices. You might not like this answer if you own one of these devices, but it makes perfect sense when you look at the bigger picture.


I told you why. Please don't try telling me how to spend my free time.

If you care about that so much, you can always learn whatever is needed or maybe hire/pay some developer/company to do that for you.

Luckily Broadcom releases code for a lot of their hardware. Wireless excluded of course.

RAM support requires kernel code, so they are actually obligated by GPL to release their modified kernel code. One just needs to download SDK for device with highmem and port Broadcom's code to the upstream kernel.


True...but stuck at Kernel 2.6...someone would have to patch that driver up to Linux Kernel 4.x.

  • Even if someone did it, they could not distribute the driver to you.
  • You'd still have to do it yourself to comply with the license.