Prepare and run Fatdog64 test build SFS-es under qemu.

Copy the currently running kernel here, name it vmlinuz.
Then run "./build-iso.sh initrd"
Then run either "./build-iso.sh single" or "./build.sh multi"
Then run ./runsfs.sh or ./runiso.sh
(the scripts can be run from this directory, or from the parent of this 
directory).

https://www.kraxel.org/blog/2019/09/display-devices-in-qemu/
VGA_TYPE that works:
- cirrus-vga (-vga cirrus)
  fbcon, modesetting or fbdev (+vesa when nomodeset && BIOS)
  ancient, slow, works (with patched Xorg to support 24-bit)
  This is currently the default 
  
- VGA (-vga std)
  fbcon, modesetting or fbdev (+vesa maxres when nomodeset && BIOS)
  newer, slow, requires BOCHS_DRM enabled (otherwise no fbcon)
  higher resolution choices than cirrus

- bochs-display
  fbcon, modesetting or fbdev (+vesa maxres when nomodeset && BIOS)
  newer, slow, requires BOCHS_DRM enabled (otherwise no fbcon)
  higher resolution choices than cirrus
  dual display (configurable with or without xinerama)

- virtio-vga (-vga virtio)
  fbcon, modesetting or fbdev
  modern, very fast, requires VIRTIO_GPU enabled
  (multi display supported when using spice only)

- virtio-gpu-pci (-vga virtio)
  fbcon, modesetting or fbdev (+vesa maxres when nomodeset && BIOS)
  modern, slow, requires VIRTIO_GPU enabled
  supposedly multi display but I can't make it work with SDL output

- ati-vga
  no fbcon, vesa
  ancient, but fast?
  higher resolution choices than cirrus

- qxl-vga (-vga qxl) - primary GPU with VGA compatibility
  fbcon, modesetting, fbdev, qxl (+vesa maxres when nomodeset && BIOS)
  modern, fast, requires DRM_QXL (otherwise no fbcon)
  Note: qxl (below) is dual display, this one qxl-vga is NOT.

- qxl - secondary GPU without 
  fbcon, modesetting, fbdev (+vesa maxres when nomodeset && BIOS)
  modern, slow, requires DRM_QXL (otherwise no fbcon)
  dual display (configurable with or without xinerama) but the cursor
  does not show up on the second monitor.
  Note: qxl driver doesn't work here, only modesetting

VGA_TYPE that does not work:
- vmware-svga (-vga vmware)
  can be made to work by modprobe.blacklist=vmwgfx
  (vmwgfx needed on real vmware, but doesn't work in qemu)
  no fbcon, vmware
  slow, and cannot use ShadowFB option to accelerate, plus
  the text console is corrupted after Xorg

- ramfb
  shows nothing (blank)

--------------

dual display for bochs-display and qxl

Section "ServerLayout"
    Identifier     "Default Layout"
    Screen      0  "Screen0" 0 0
    Screen      1  "Screen1" RightOf "Screen0"
    Option         "Xinerama" "off" # default, use "on" to turn on
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "modesetting"
    Option         "kmsdev" "/dev/dri/card0"
    Option         "ShadowFB" "on"
    Option         "DoubleShadow" "on"
EndSection

Section "Device"
    Identifier     "Device1"
    Driver         "modesetting"
    Option         "kmsdev" "/dev/dri/card1"
    Option         "ShadowFB" "on"
    Option         "DoubleShadow" "on"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
EndSection

Section "Monitor"
    Identifier     "Monitor1"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    SubSection     "Display"
        Modes       "1024x768"
    EndSubSection
EndSection

Section "Screen"
    Identifier     "Screen1"
    Device         "Device1"
    Monitor        "Monitor1"
    SubSection     "Display"
        Modes       "1024x768"
    EndSubSection
EndSection


-----------------------------------------

Directory sharing is now supported.

Do this inside the guest:

If SHARE= is specified:
	mount -t 9p -o trans=virtio share /path
If SHARE_RW= is specified:
	mount -t 9p -o trans=virtio share-rw /path

Both SHARE and SHARE_RW can be specified (pointing at same or different dir).
Ref: https://wiki.qemu.org/Documentation/9psetup
Ref: https://wiki.qemu.org/Documentation/9psetup
