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From: Nicola Girardi <ng@0x80.stream>
Date: Sat, 03 Dec 2022 09:48:59 +0000
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Subject: Re: [9front] Question re: RPI video performance
Reply-To: 9front@9front.org
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Sigrid Solveig Hafl=C3=ADnud=C3=B3ttir <sigrid@ftrv.se> wrote:
> Could be related to the framebuffer format. Check "aux/zerotrunc </dev/=
screen". Try to switch to a different format via config.txt(?), especiall=
y if your current mode is 16-bit.

Interesting.  I had only configured the mode using hdmi_mode=3D82 in
config.txt and got r5g6b5 as output to your command.  I now realize I
can additionally set vgasize in cmdline.txt to 1920x1080x32, then I
get

; read -c 60 /dev/screen
   x8r8g8b8           0           0        1920        1080=20

Slow as before.  Tried many other modes in the past month, and even
640x350 behaves in the same way I'd described earlier.

One thing I noticed in the config.txt provided by 9front is that
gpu_mem is set to 16, while the default is 64.  As a total hunch I
tried to increase that value to 64 but then the RPI doesn't boot (or
boots, but screen is blank so I don't know :-)).

I can accept the behavior, it's just I'd like to understand more.  I
tried to understand something from the git history but failed.