On Sun, Nov 7, 2021 at 2:04 PM Wol <[email protected]> wrote: > > On 07/11/2021 20:39, Mark Knecht wrote: > > Hi, > > I've been playing with a Raspberry Pi 4 as a utility divice for a > > couple of purposes - a backup server for here at home as well as an > > astrophotography manager to run my camera and mount. So far everything > > is fine when I have a monitor attached. I can ssh in and run X apps, > > and I can run the VNC client and control the desktop. > > > > What I find, however, is that when I boot the RP4 without the > > monitor attached, which I would be doing most all the time, I lose the > > desktop functionality through VNC. I can still ssh X apps, and both > > xdpyinfo and xrandr still say the X resolution is 1920 x 1280, but > > there doesn't appear to be a real desktop for VNC to latch onto. > > > > I get that this must be possible as essentially VirtualBox is able > > to do this. I wonder if there's a way for mere mortals to do something > > similar? > > > I'm guessing the reason there isn't a virtual desktop is because > nobody's logged in AT THE PI and started one! > > Just start Xorg over ssh, or plasma-wayland, or whatever. Sorry I don't > (yet) know how to do it, I need to find out because I want to do exactly > the same :-) > > Cheers, > Wol >
It seems so far that it's even a little more onerous than that: In the case where the monitor is detached at boot two modules are not loaded - fuse & nvmem_rmem. Other than that the module list appears identical. If I ssh into the RP4 when it's running RPi OS (previously called Raspbian apparently) but with the monitor DISCONNECTED when I boot then screenfetch says there's no GPU. Plugging in the monitor after it's booted doesn't change anything: mark@science:~$ ssh -X [email protected] [email protected]'s password: Linux raspberrypi 5.10.63-v7l+ #1459 SMP Wed Oct 6 16:41:57 BST 2021 armv7l <SNIP> pi@raspberrypi:~ $ screenfetch -nN pi@raspberrypi OS: Raspbian 10 buster Kernel: armv7l Linux 5.10.63-v7l+ Uptime: 0m Packages: 2038 Shell: 723 Resolution: 5760x1080 DE: KDE5 WM: KWin CPU: ARMv7 rev 3 (v7l) @ 4x 1.5GHz [29.6°C] GPU: RAM: 61MiB / 7898MiB pi@raspberrypi:~ $ lspci -vm -k Device: 00:00.0 Class: PCI bridge Vendor: Broadcom Limited Device: Device 2711 Rev: 10 Driver: pcieport Device: 01:00.0 Class: USB controller Vendor: VIA Technologies, Inc. Device: VL805 USB 3.0 Host Controller SVendor: VIA Technologies, Inc. SDevice: VL805 USB 3.0 Host Controller Rev: 01 ProgIf: 30 Driver: xhci_hcd pi@raspberrypi:~ $ However, booting with the monitor ATTACHED now shows the GPU, or at least a DRM framebuffer possibly, in screenfetch. The PCI devices are the same: pi@raspberrypi:~ $ screenfetch -nN pi@raspberrypi OS: Raspbian 10 buster Kernel: armv7l Linux 5.10.63-v7l+ Uptime: 0m Packages: 2038 Shell: 935 Resolution: 3840x1080 DE: KDE5 WM: OpenBox CPU: ARMv7 rev 3 (v7l) @ 4x 1.5GHz [37.9°C] GPU: vc4drmfb RAM: 144MiB / 7898MiB pi@raspberrypi:~ $ pi@raspberrypi:~ $ lspci -vm -k Device: 00:00.0 Class: PCI bridge Vendor: Broadcom Limited Device: Device 2711 Rev: 10 Driver: pcieport Device: 01:00.0 Class: USB controller Vendor: VIA Technologies, Inc. Device: VL805 USB 3.0 Host Controller SVendor: VIA Technologies, Inc. SDevice: VL805 USB 3.0 Host Controller Rev: 01 ProgIf: 30 Driver: xhci_hcd pi@raspberrypi:~ $ I will repeat this experiment using Ubuntu in a little while to see if the missing GPU is an OS or hardware thing. In this hardware it looks like the GPU hardware is behind the PCI bridge. Still to look into Neil's x2go suggestion. Mark
