when I start X the xdpyinfo and xrandr report basically the same physical size, and the DPI is correct. however, when I rotate the screen with xrandr --orientation 3 the width and height in pixels are swapped, and the width in mm and height in mm are not, resulting in asymmetric wrong DPI. xrandr --output <myouputname> --rotation right results in correct DPI but I have to know the name of the output. Note also the inconsistent interface, the values are not interchangeable. It also seems repeatedly changing screen layout like this reduces the physical screen size reported by xdpyinfo slowly.
Created attachment 20442 [details] script that causes reported physical size to shrink 271->215 mm
Screen size is no longer changed. DPI breaks, however, which is bug 692. *** This bug has been marked as a duplicate of bug 692 ***
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