15 MB more memory (RAM)

MarekGibek · 09-27-2013, 03:41 PM

A very simple change (of 1 line of code) in the kernel sources will give you ~15 MB more memory (RAM) on your kobo. The change is:
https://github.com/marek-g/kobo-kern...7d3b4a487ed200

If you are using my image (https://www.mobileread.com/forums/sho...d.php?t=220350) with Firefox it will give you much better web browsing experience.

So what's the price?

The parameter reduces number of video buffers used for concurrent screen updates. eInk controller can update up to 15 screen regions at the same time (if requested). But most of the time large areas are updated and having too many buffers makes no sense if you can trade it for memory.

I was suprised that I couldn't see almost any negative impact after that change. Except less frequent updates of mouse cursor in X11 (which I would like to hide anyway). I even think that overall experience is even better now:

less crazy flickering of motion areas that could trigger multiple refreshes before
less CPU usage

Original kobo firmware works as always (no difference noticed). Having more memory original kobo's web browser will crash later

KevinShort · 09-27-2013, 04:27 PM

Very nice hack!

nicolas161 · 04-18-2018, 03:56 AM

Is this still relevant?

frostschutz · 04-18-2018, 05:38 AM

older kobos like mini, touch only had 256MB of RAM, newer ones have at least 512MB.

I guess with +256MB RAM compared to before a ~10MBish difference will no longer pull that much weight.

Not sure about refresh behavior. I've never patched my kernel

09-27-2013, 03:41 PM	#1
MarekGibek Zealot Posts: 129 Karma: 34471 Join Date: Aug 2013 Location: Cracow, Poland Device: Kobo Touch N905C	15 MB more memory (RAM) A very simple change (of 1 line of code) in the kernel sources will give you ~15 MB more memory (RAM) on your kobo. The change is: https://github.com/marek-g/kobo-kern...7d3b4a487ed200 If you are using my image (https://www.mobileread.com/forums/sho...d.php?t=220350) with Firefox it will give you much better web browsing experience. So what's the price? The parameter reduces number of video buffers used for concurrent screen updates. eInk controller can update up to 15 screen regions at the same time (if requested). But most of the time large areas are updated and having too many buffers makes no sense if you can trade it for memory. I was suprised that I couldn't see almost any negative impact after that change. Except less frequent updates of mouse cursor in X11 (which I would like to hide anyway). I even think that overall experience is even better now: less crazy flickering of motion areas that could trigger multiple refreshes before less CPU usage Original kobo firmware works as always (no difference noticed). Having more memory original kobo's web browser will crash later Last edited by MarekGibek; 09-27-2013 at 03:45 PM.

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09-27-2013, 04:27 PM	#2
KevinShort Addict Posts: 348 Karma: 209937 Join Date: Jan 2012 Location: Virginia, US Device: Kobo Wifi, Kobo Glo	Very nice hack!

04-18-2018, 03:56 AM	#3
nicolas161 Enthusiast Posts: 27 Karma: 35026 Join Date: Jun 2014 Device: Kobo Glo HD	Is this still relevant?

04-18-2018, 05:38 AM	#4
frostschutz Linux User Posts: 2,279 Karma: 6123806 Join Date: Sep 2010 Location: Heidelberg, Germany Device: none	older kobos like mini, touch only had 256MB of RAM, newer ones have at least 512MB. I guess with +256MB RAM compared to before a ~10MBish difference will no longer pull that much weight. Not sure about refresh behavior. I've never patched my kernel

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