1: [[!meta title="How to use Xorg's wsfb display driver with a UEFI/BIOS framebuffer, and change its resolution"]]
2: [[!toc levels=3]]
3:
4: Background
5: ----------
6: [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.)
7:
8: `wsdisplay(4)` can run on top of:
9:
10: 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)
11: 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).
12:
13: Using `wsfb`
14: ------------
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: ```
28: $ fgrep directory /var/log/Xorg.0.log
29: [ 72.697] (==) Using config directory: "/usr/local/etc/X11/xorg.conf.d"
30: [ 72.697] (==) Using system config directory "/usr/local/share/X11/xorg.conf.d"
31: ```
32:
33: 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.
34:
35: 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.
36:
37: ### Step 2: Setting a better display mode.
38: 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:
39:
40: List available video modes first:
41:
42: ```
43: > gop list
44: 0: 1366x768 BGRR pitch 1376 bpp 32
45: 1: 640x480 BGRR pitch 640 bpp 32
46: *2: 800x600 BGRR pitch 800 bpp 32
47: 3: 1024x768 BGRR pitch 1024 bpp 32
48: >
49: ```
50:
51: 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.
52:
53: Choose the best mode, which is generally mode `0`:
54:
55: ```
56: > gop 0
57: >
58: ```
59:
60: 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.)
61:
62: If you have/use BIOS instead of UEFI, you can try the `vesa` command instead of `gop`:
63:
64: ```
65: > vesa list
66: ...
67: > vesa 0xhhh
68: >
69: ```
70:
71: 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.
72:
73: This is what `dmesg` will show, if you've disabled DRM (see below), or don't have it:
74:
75: ```
76: $ dmesg | fgrep genfb
77: [ 1.015430] genfb0 at pci0 dev 2 function 0: vendor 8086 product 0166 (rev. 0x09)
78: [ 1.015430] genfb0: framebuffer at 0xe0000000, size 1366x768, depth 32, stride 5504
79: [ 1.015430] genfb0: shadow framebuffer enabled, size 4128 KB
80: [ 1.015430] wsdisplay0 at genfb0 kbdmux 1: console (default, vt100 emulation), using wskbd0
81: [ 1.015430] drm at genfb0 not configured
82: ```
83:
84: The resolution, depth and stride are all OK. And inside the Xorg server:
85:
86: ```
87: $ xdpyinfo | fgrep -B1 -A1 resolution
88: dimensions: 1366x768 pixels (310x174 millimeters)
89: resolution: 112x112 dots per inch
90: depths (7): 24, 1, 4, 8, 15, 16, 32
91: $ xrandr
92: xrandr: Failed to get size of gamma for output default
93: Screen 0: minimum 1366 x 768, current 1366 x 768, maximum 1366 x 768
94: default connected 1366x768+0+0 0mm x 0mm
95: 1366x768 0.00*
96: $
97: ```
98:
99: Limitations
100: -----------
101: 1. No OpenGL hardware acceleration - on x86 and aarch64, llvmpipe (a parallel CPU-based just-in-time renderer) will be used instead
102: 2. No X Display Power Management Signaling
103: 3. No X video extension (used for accelerated video playback)
104: 4. No DRI
105:
106: ## Extra: How to disable built-in DRM driver using kernel's `userconf` manager
107:
108: For testing, or if running `wsfb` on top of the DRM graphics driver does not work--it mostly should, actually).
109:
110: At the bootloader prompt, pass the `-c` flag to the kernel:
111:
112: ```
113: > boot -c
114: ```
115:
116: The kernel will display a few lines, then immediately drop into the `userconf` prompt:
117:
118: ```
119: uc> list # list all devs; look for your drmkms entry
120: uc> disable i915drmkms # disable Intel DRM
121: uc> quit
122: ```
123:
124: 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:
125:
126: ```
127: > userconf disable i915drmkms
128: ```
129:
130: You can of course, add `userconf` commands also to `boot.conf`
131:
132: ## Minimal `wsfb(4)` config fragment `/etc/X11/xorg.conf.d/wsfb.conf`
133:
134: ```
135: Section "Device"
136: Identifier "Card0"
137: Driver "wsfb"
138: EndSection
139: ```
140:
141: ## Minimal `wsfb(4)` `/etc/X11/xorg.conf`
142:
143: Created using `X -configure`, and then changing the graphics device driver (`Section "Device"`) from `intel` to `wsfb`
144:
145: ```
146: Section "ServerLayout"
147: Identifier "X.org Configured"
148: Screen 0 "Screen0" 0 0
149: InputDevice "Mouse0" "CorePointer"
150: InputDevice "Keyboard0" "CoreKeyboard"
151: EndSection
152:
153: Section "Files"
154: ModulePath "/usr/X11R7/lib/modules"
155: FontPath "/usr/X11R7/lib/X11/fonts/misc/"
156: FontPath "/usr/X11R7/lib/X11/fonts/TTF/"
157: FontPath "/usr/X11R7/lib/X11/fonts/Type1/"
158: FontPath "/usr/X11R7/lib/X11/fonts/75dpi/"
159: FontPath "/usr/X11R7/lib/X11/fonts/100dpi/"
160: EndSection
161:
162: Section "Module"
163: Load "dri"
164: Load "dri2"
165: Load "glx"
166: Load "shadow"
167: EndSection
168:
169: Section "InputDevice"
170: Identifier "Keyboard0"
171: Driver "kbd"
172: EndSection
173:
174: Section "InputDevice"
175: Identifier "Mouse0"
176: Driver "mouse"
177: Option "Protocol" "wsmouse"
178: Option "Device" "/dev/wsmouse"
179: Option "ZAxisMapping" "4 5 6 7"
180: EndSection
181:
182: Section "Monitor"
183: Identifier "Monitor0"
184: VendorName "Monitor Vendor"
185: ModelName "Monitor Model"
186: EndSection
187:
188: Section "Device"
189: Identifier "Card0"
190: Driver "wsfb"
191: EndSection
192:
193: Section "Screen"
194: Identifier "Screen0"
195: Device "Card0"
196: Monitor "Monitor0"
197: SubSection "Display"
198: Viewport 0 0
199: Depth 1
200: EndSubSection
201: SubSection "Display"
202: Viewport 0 0
203: Depth 4
204: EndSubSection
205: SubSection "Display"
206: Viewport 0 0
207: Depth 8
208: EndSubSection
209: SubSection "Display"
210: Viewport 0 0
211: Depth 15
212: EndSubSection
213: SubSection "Display"
214: Viewport 0 0
215: Depth 16
216: EndSubSection
217: SubSection "Display"
218: Viewport 0 0
219: Depth 24
220: EndSubSection
221: EndSection
222: ```
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