So far my experiment to bypass the RX 550 by displaying on another computer has been a success, i.e., no lock up issues have been encountered under this mode of operation. So it is a rather short (roughly one day) test so far but still consistent with the hypothesis that the lock ups are likely caused by an issue with xserver-xorg-video-amdgpu itself or the kernel functions that are used by that device driver.
Also, assuming I have now found a stable mode of operation for this new computer that is not subject to lock ups, I would like to test the RX 550 for latest kernel and X to see if the lock ups (for direct display) go away. Can you advise on the best way to build the latest kernel and X so those choices are easy to use with Debian Buster without compromising the Debian Buster versions of kernel and X? (I am experienced at software builds, but it has been many years since I built the Linux kernel, and I have no experience building X, yet.) I have also reported this bug upstream at <https://bugs.freedesktop.org/show_bug.cgi?id=106671> in case the X developers have helpful advice about working around the problem or want me to perform some specific tests. Alan __________________________ Alan W. Irwin Astronomical research affiliation with Department of Physics and Astronomy, University of Victoria (astrowww.phys.uvic.ca). Programming affiliations with the FreeEOS equation-of-state implementation for stellar interiors (freeeos.sf.net); the Time Ephemerides project (timeephem.sf.net); PLplot scientific plotting software package (plplot.sf.net); the libLASi project (unifont.org/lasi); the Loads of Linux Links project (loll.sf.net); and the Linux Brochure Project (lbproject.sf.net). __________________________ Linux-powered Science __________________________