panic: Too many early devmap mappings

[bob prohaska]

On Tue, Jan 12, 2021 at 10:53:00PM -0800, Mark Millard wrote:
[trimmed for brevity]
> On 2021-Jan-12, at 16:55, Mark Millard <marklmi at yahoo.com> wrote:
> 
> 
> I forgot to list the bugzilla for this:
> 
> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=252541
> 
> I have added the notes, including:
> 
> QUOTE
> Turns out that this "too much high kernel memory in use" issue happens for
> a combination of 2 things being true at the same time:
> 
> A) Monitor attached (sufficiently large pixel count?)
> B) GDB enabled, per bbfa199cbc16 .
> END QUOTE
> 

Just for fun I re-connected the monitor after the Pi3 had booted. 
It didn't work, which I _think_ is normal for a Pi booted without
a monitor. 

The console reported:
MESS:00:43:36.897488:0: hdmi: HDMI:>>>>>>>>>>>>>Rx sensed, reading EDID<<<<<<<<<<<<<
MESS:00:43:36.915571:0: hdmi: HDMI:EDID version 1.3, 0 extensions, screen size 52x33 cm
MESS:00:43:36.921928:0: hdmi: HDMI:EDID features - videodef 0x80 standby suspend active off; colour encoding:RGB444|YCbCr444|YCbCr422; sRGB is default colourspace; preferred format is native; does not support GTF
MESS:00:43:36.940534:0: hdmi: HDMI:EDID found preferred DMT detail timing format: 1920x1200p @ 60 Hz (68)
MESS:00:43:36.949773:0: hdmi: HDMI:EDID found DMT format: code 4, 640x480p @ 60 Hz in established timing I/II
MESS:00:43:36.959407:0: hdmi: HDMI:EDID found DMT format: code 6, 640x480p @ 75 Hz in established timing I/II
MESS:00:43:36.969044:0: hdmi: HDMI:EDID found DMT format: code 9, 800x600p @ 60 Hz in established timing I/II
MESS:00:43:36.978682:0: hdmi: HDMI:EDID found DMT format: code 11, 800x600p @ 75 Hz in established timing I/II
MESS:00:43:36.988408:0: hdmi: HDMI:EDID found DMT format: code 16, 1024x768p @ 60 Hz in established timing I/II
MESS:00:43:36.998218:0: hdmi: HDMI:EDID found DMT format: code 18, 1024x768p @ 75 Hz in established timing I/II
MESS:00:43:37.008032:0: hdmi: HDMI:EDID found DMT format: code 36, 1280x1024p @ 75 Hz in established timing I/II
MESS:00:43:37.017975:0: hdmi: HDMI:EDID standard timings block x 8: 0x8180 A940 714F B300 0101 0101 0101 0101 
MESS:00:43:37.027665:0: hdmi: HDMI:EDID found DMT format: code 35, 1280x1024p @ 60 Hz (5:4) in standard timing 0
MESS:00:43:37.037562:0: hdmi: HDMI:EDID found DMT format: code 51, 1600x1200p @ 60 Hz (4:3) in standard timing 1
MESS:00:43:37.047457:0: hdmi: HDMI:EDID found DMT format: code 21, 1152x864p @ 75 Hz (4:3) in standard timing 2
MESS:00:43:37.057272:0: hdmi: HDMI:EDID found DMT format: code 58, 1680x1050p @ 60 Hz (16:10) in standard timing 3
MESS:00:43:37.067327:0: hdmi: HDMI:EDID filtering formats with pixel clock > 162 MHz or h. blanking > 1023
MESS:00:43:37.076805:0: hdmi: HDMI:EDID preferred mode remained as DMT (68) 1920x1200p @ 60 Hz with pixel clock 154 MHz
MESS:00:43:37.087189:0: hdmi: HDMI: hotplug attached with DVI support
MESS:00:44:41.995274:0: hdmi: HDMI: hotplug deassert
MESS:00:44:41.998532:0: hdmi: HDMI: HDMI is currently off
MESS:00:44:42.003654:0: hdmi: HDMI: changing mode to unplugged

Thanks for reading,

bob prohaska