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    1: [[[!meta title="How to use Xorg's wsfb display driver with a UEFI/BIOS framebuffer, and change its resolution"]]
    2: 
    3: How to use Xorg's wsfb display driver with a UEFI/BIOS framebuffer, and change its resolution
    4: =============================================================================================
    5: 
    6: ### Background
    7: [wsfb(4)](https://man.netbsd.org/wsfb.4) is the Xorg graphics driver for the NetBSD [wsdisplay(4)](https://man.netbsd.org/wsdisplay.4) framebuffer device. `wsdisplay(4)`, similar to Linux's `/dev/fb` devices, provide access to _non-accelerated_ framebuffers, which are provided by _almost all_ modern cards. Most, if not all, _modern_ graphics cards provide what's called a _linear_ framebuffer: a chunk of memory where contiguous address locations map onto adjacent (X, Y) _pixels_. For example, assuming a 32 bits-per-pixel colour depth display, memory location `fbmem + 0` will hold the pixel at position (0,0); `fbmem + 4` corresponds to the pixel at (1, 0), and so on. (We'll skip the complication known as `stride` or `line_length` here.)
    8: 
    9: `wsdisplay(4)` can run on top of: 
   10: 
   11: 1. `genfb(4)`, the Generic PCI VGA framebuffer device (provided by UEFI or BIOS on x86), and other simple software framebuffers provided by hardware or firmware (e.g. simplefb on ARM)
   12: 2. the accelerated [`drm(4)`](https://man.netbsd.org/drm.4) graphics devices (in `/dev/dri/card?`--which `wsfb` will use as a plain framebuffer).
   13: 
   14: ### Using `wsfb`
   15: ### Step 1: Configuring `Xorg`
   16: Use this `wsfb.conf` Xorg config fragment:
   17:  
   18: ```
   19: Section "Device"
   20: 	Identifier  "Card0"
   21: 	Driver      "wsfb"
   22: EndSection
   23: ```
   24: 
   25: That is all that is needed. Xorg will autoconfigure everything else. Make sure you dump the `wsfb.conf` file into the correct Xorg config. directory. `/etc/X11/xorg.conf.d/` is the correct location for the Xorg in base. If you've installed the `modular-xorg` package, then the path will need change. Use this command to find your `config directory`:
   26: ```
   27: $ fgrep directory /var/log/Xorg.0.log
   28: [    72.697] (==) Using config directory: "/usr/local/etc/X11/xorg.conf.d"
   29: [    72.697] (==) Using system config directory "/usr/local/share/X11/xorg.conf.d"
   30: ```
   31: 
   32: If your DRM kernel driver has loaded OK and is active, then it will have configured your graphics card with the best resolution for your screen and you can just run `X` right away (this wil be X with `wsfb` on `drmkms`, minus the DRM-provided accelerations). You don't need Step 2.
   33: 
   34: If you don't have a DRM driver, or if you can't load it, then if you start `X` now, you'll most probably get the bog-standard 1024x768x32 screen resolution provided by `genfb`, which might be OK, but, is not ideal. As the `wsfb`/`wsdisplay`/`genfb` combo. doesn't let you change resolutions on the fly (`xrandr`, for instance, doesn't work), we'll have to set a better resolution elsewhere: in the bootloader.
   35: 
   36: ### Step 2: Setting a better display mode.
   37: Reboot, then at the bootloader menu, choose the option to get to the bootloader prompt. Here, on UEFI systems, we use the `gop` (Graphics Output Protocol) command like this:
   38: List avaibable video modes first:
   39: ```
   40: > gop list
   41:  0: 1366x768 BGRR pitch 1376 bpp 32
   42:  1: 640x480 BGRR pitch 640 bpp 32
   43: *2: 800x600 BGRR pitch 800 bpp 32
   44:  3: 1024x768 BGRR pitch 1024 bpp 32
   45: >
   46: ```
   47: The `*` indicates the (safe) mode that the bootloader will use by default. Note that on my laptop, mode `0` has a pitch (aka stride) of 1376 pixels. This means that on my graphics card (Asus X202E laptop), the framebuffer is _linear_, but, **not** fully contiguous. The 10 unusable pixels at the end of each row have to taken into account, or else, you'll be treated to a characteristic jagged, streaky display.
   48: 
   49: Choose the best mode, which is generally mode `0`:
   50: ```
   51: > gop 0
   52: >
   53: ```
   54: The screen resolution will switch immediately. (And hopefully, your display won't go blank, which, these days, usually indicates a graphics card/BIOS/UEFI/whatever that doesn't implement the published standards correctly.)
   55: 
   56: If you have/use BIOS instead of UEFI, you can try the `vesa` command instead of `gop`:
   57: 
   58: ```
   59: > vesa list
   60: ...
   61: > vesa 0xhhh
   62: >
   63: ```
   64: If the mode you've chosen works, then you can add that `gop 0` or `vesa mode` command to `boot.cfg` so that it is activated automatically.
   65: 
   66: This is what `dmesg` will show, if you've disabled DRM (see below), or don't have it:
   67: ```
   68: $ dmesg | fgrep genfb
   69: [     1.015430] genfb0 at pci0 dev 2 function 0: vendor 8086 product 0166 (rev. 0x09)
   70: [     1.015430] genfb0: framebuffer at 0xe0000000, size 1366x768, depth 32, stride 5504
   71: [     1.015430] genfb0: shadow framebuffer enabled, size 4128 KB
   72: [     1.015430] wsdisplay0 at genfb0 kbdmux 1: console (default, vt100 emulation), using wskbd0
   73: [     1.015430] drm at genfb0 not configured
   74: ```
   75: The resolution, depth and stride are all OK. And inside the Xorg server:
   76: ```
   77: $ xdpyinfo | fgrep -B1 -A1 resolution
   78:   dimensions:    1366x768 pixels (310x174 millimeters)
   79:   resolution:    112x112 dots per inch
   80:   depths (7):    24, 1, 4, 8, 15, 16, 32
   81: $ xrandr
   82: xrandr: Failed to get size of gamma for output default
   83: Screen 0: minimum 1366 x 768, current 1366 x 768, maximum 1366 x 768
   84: default connected 1366x768+0+0 0mm x 0mm
   85:    1366x768       0.00* 
   86: $
   87: ```
   88: 
   89: ### Limitations
   90: 1. No OpenGL hardware acceleration - on x86 and aarch64, llvmpipe (a parallel CPU-based just-in-time renderer) will be used instead
   91: 2. No X Display Power Management Signaling
   92: 3. No X video extension (used for accelerated video playback)
   93: 4. No DRI
   94: 
   95: #### Extra: How to disable built-in DRM driver using kernel's `userconf` manager
   96: 
   97: For testing, or if running `wsfb` on top of the DRM graphics driver does not work--it mostly should, actually).
   98: 
   99: At the bootloader prompt, pass the `-c` flag to the kernel:
  100: ```
  101: > boot -c
  102: ```
  103: The kernel will display a few lines, then immediately drop into the `userconf` prompt:
  104: ```
  105: uc> list                        # list all devs; look for your drmkms entry
  106: uc> disable i915drmkms          # disable Intel DRM
  107: uc> quit
  108: ```
  109: Once you've determined the device name using `userconf`, or, by trawling through the GENERIC kernel config file, you can disable the device using the bootloader like this:
  110: ```
  111: > userconf disable i915drmkms
  112: ```
  113: You can of course, add `userconf` commands also to `boot.conf`
  114: 
  115: #### Minimal `wsfb(4)` config fragment `/etc/X11/xorg.conf.d/wsfb.conf`
  116: ```
  117: Section "Device"
  118: 	Identifier  "Card0"
  119: 	Driver      "wsfb"
  120: EndSection
  121: ```
  122: 
  123: #### Minimal `wsfb(4)` `/etc/X11/xorg.conf` created using `X -configure`, and then changing the graphics device driver (`Section "Device"`) from `intel` to `wsfb`
  124: 
  125: ```
  126: Section "ServerLayout"
  127: 	Identifier     "X.org Configured"
  128: 	Screen      0  "Screen0" 0 0
  129: 	InputDevice    "Mouse0" "CorePointer"
  130: 	InputDevice    "Keyboard0" "CoreKeyboard"
  131: EndSection
  132: 
  133: Section "Files"
  134: 	ModulePath   "/usr/X11R7/lib/modules"
  135: 	FontPath     "/usr/X11R7/lib/X11/fonts/misc/"
  136: 	FontPath     "/usr/X11R7/lib/X11/fonts/TTF/"
  137: 	FontPath     "/usr/X11R7/lib/X11/fonts/Type1/"
  138: 	FontPath     "/usr/X11R7/lib/X11/fonts/75dpi/"
  139: 	FontPath     "/usr/X11R7/lib/X11/fonts/100dpi/"
  140: EndSection
  141: 
  142: Section "Module"
  143: 	Load  "dri"
  144: 	Load  "dri2"
  145: 	Load  "glx"
  146: 	Load  "shadow"
  147: EndSection
  148: 
  149: Section "InputDevice"
  150: 	Identifier  "Keyboard0"
  151: 	Driver      "kbd"
  152: EndSection
  153: 
  154: Section "InputDevice"
  155: 	Identifier  "Mouse0"
  156: 	Driver      "mouse"
  157: 	Option	    "Protocol" "wsmouse"
  158: 	Option	    "Device" "/dev/wsmouse"
  159: 	Option	    "ZAxisMapping" "4 5 6 7"
  160: EndSection
  161: 
  162: Section "Monitor"
  163: 	Identifier   "Monitor0"
  164: 	VendorName   "Monitor Vendor"
  165: 	ModelName    "Monitor Model"
  166: EndSection
  167: 
  168: Section "Device"
  169: 	Identifier  "Card0"
  170: 	Driver      "wsfb"
  171: EndSection
  172: 
  173: Section "Screen"
  174: 	Identifier "Screen0"
  175: 	Device     "Card0"
  176: 	Monitor    "Monitor0"
  177: 	SubSection "Display"
  178: 		Viewport   0 0
  179: 		Depth     1
  180: 	EndSubSection
  181: 	SubSection "Display"
  182: 		Viewport   0 0
  183: 		Depth     4
  184: 	EndSubSection
  185: 	SubSection "Display"
  186: 		Viewport   0 0
  187: 		Depth     8
  188: 	EndSubSection
  189: 	SubSection "Display"
  190: 		Viewport   0 0
  191: 		Depth     15
  192: 	EndSubSection
  193: 	SubSection "Display"
  194: 		Viewport   0 0
  195: 		Depth     16
  196: 	EndSubSection
  197: 	SubSection "Display"
  198: 		Viewport   0 0
  199: 		Depth     24
  200: 	EndSubSection
  201: EndSection
  202: ```

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