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I am trying to track down the following issue in Debian Jessie on PowerPC. Per bogl-bterm package maintainer the issue is simply that bterm makes uses of FBIOPUTCMAP, see ref here.

So before even trying to patch the linux kernel, I would like to prepare a simple way to reproduce the issue as the original report is done within a minimal setup during Debian installation process. It would be a lot of pain to install localechooser on a regular Debian system since this is a udeb package.

So I would like to know if a Linux framebuffer expert could point me in the right direction to reproduce this palette inversion ?

I had naively assumed that I would be able to reproduce the bug using something as simple as:

Print in blue:

# dd if=/dev/zero ibs=1K count=600 | tr '\000' '\001' > /dev/fb0

Print in red:

# dd if=/dev/zero ibs=1K count=600 | tr '\000' '\004' > /dev/fb0

But since it does not work, this means I am playing directly with the color buffer of the framebuffer instead of using the palette one.

What tools can I install on a regular Debian system (PowerPC) to play with the palette (FBIOPUTCMAP) ?


Update: the description of the above symptoms may be relatively confusing, but really what I am looking is minimal code that exercise ioctl/FBIOGETCMAP/FBIOPUTCMAP so as to see the red / blue inversion in minimal code.

migrated from superuser.com Oct 8 '16 at 17:26

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  • FBIOPUTCMAP refers to an ioctl call. Writing to the raw device probably is the wrong approach. – Thomas Dickey Oct 8 '16 at 17:28
  • No one's written a tutorial for this; you can easily find it used in source-code, e.g., this. – Thomas Dickey Oct 11 '16 at 8:26

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