salvaliebana
Posts: 59
Joined: Wed Sep 13, 2017 3:27 am

The dtoverlay=vc4-kms-v3d overlay and memory allocation

Sat Feb 23, 2019 9:43 pm

Hi everyone!!

The problem its than I need to add more memory to the dtoverlay vc4-kms-v3d overlay and I tried by three ways.

1) with "dtoverlay=vc4-kms-v3d,cma-256" on config.txt
2) with "[email protected]" on cmdline.txt
3)both


none of these "solutions" give me any help on this topic.
I use gpu_mem=64 because that doesn't effects my layer memory bandwidth.

maybe I need to unpack and edit the .dtbo?

Hope some help here!! :)

cjan
Posts: 744
Joined: Sun May 06, 2012 12:00 am

Re: The dtoverlay=vc4-kms-v3d overlay and memory allocation

Sun Feb 24, 2019 9:20 am

in my case
1. dtoverlay=vc4-kms-v3d & gpu_mem=16
2. none
3. none

6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 7533
Joined: Wed Dec 04, 2013 11:27 am
Location: ZZ9 Plural Z Alpha, aka just outside Cambridge.

Re: The dtoverlay=vc4-kms-v3d overlay and memory allocation

Sun Feb 24, 2019 4:08 pm

All of those options allocate a cma heap of 256MB, with case 2 also putting an alignment restriction on it.

You need more than 256MB of cma for some reason? I vaguely recall that there is a limit on the max usable by vc4 anyway, but I may be wrong on that.
Putting cma=384M into cmdline.txt would be the easiest option to try.
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salvaliebana
Posts: 59
Joined: Wed Sep 13, 2017 3:27 am

Re: The dtoverlay=vc4-kms-v3d overlay and memory allocation

Sun Feb 24, 2019 5:45 pm

I am running out of memory on some games, they hang on precaching. I need more ram for my vc4 overlay. dont know how it works as an overlay on memory allocation, I just need more ram to it nad these are some tips than some advance users gave me. by default its set to 64, i tried 256 but i am running out anyway. how to check that? how to measure this split when the actual gpu/cpu memory split didnt do nothing and confuses the thing?

salvaliebana
Posts: 59
Joined: Wed Sep 13, 2017 3:27 am

Re: The dtoverlay=vc4-kms-v3d overlay and memory allocation

Sun Feb 24, 2019 5:54 pm

I did precaching on legacy driver (under retropie) of huge amounts on hd textures and never has this issue. that because the gpu/cpu memory splits actually works... but with the overlay its different in some way. gpu_mem doesnt affect it (by obvious reasons) and even get the things worst. dont know how interact the normal split with the overlay, because you need 64 for video playback but more its unnecessary.

salvaliebana
Posts: 59
Joined: Wed Sep 13, 2017 3:27 am

Re: The dtoverlay=vc4-kms-v3d overlay and memory allocation

Wed Feb 27, 2019 5:33 am

I found than cma its at256 by default. I will try your cmd line. But maybe the overlay will ignore that by default because the max cma option inside the overlay dtb its 256. I will try to edit the dtb if thats the case. Thanks!

salvaliebana
Posts: 59
Joined: Wed Sep 13, 2017 3:27 am

Re: The dtoverlay=vc4-kms-v3d overlay and memory allocation

Thu Feb 28, 2019 2:46 am

Yes! your tip works! Solved!!

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