thanks, robert. if there was trouble before, then it makes sense that open editing was closed down. who does one send suggestions (experiences) to? are they even wanted? the good news is that everything posted here also goes into the google store when people are searching.
I know for sure now that my Samsung Syncmaster 213T from 2005 is a big part of the problem. it comes up black at boot, and does not get any better later. I tried replacing the default "quiet" in uEnv.txt with "verbose" and eventually with nothing. I also tried it with various video= command switches. I tried everything from 800x600@60e to 1600x1200@60e, but the samsung and bbb just don't seem to get along.
I then tried a newer low-end DELL monitor (same cable). the hdmi also comes up black at boot. I am guessing that, because the bbb hdmi port is not dedicated, it first needs to be switched on somewhere during the boot process. fortunately, the DELL monitor eventually does come up visibly for the login prompt.
I am logged into the bbb via usb-ssh right now. grepping for hdmi
(or edid)
tells me about pinmux mode and davinci sound, but nothing
interesting about where the hdmi went wrong.
* is there a command line utility over ssh to experiment instantaneously with setting different video modes on the hdmi port?
fbset -xres ... -yres ... makes no difference on the physical display, although "fbset -s" tells me that it thinks it executed..
* or a way to get more debugging information about hdmi, possibly into dmesg? even learning whether the bbb thinks that a connection over hdmi has been established would be useful. (together, these two would make it easy for a user to script a fallback.) /proc/fb only contains "0".