96 lines
3.1 KiB
Markdown
96 lines
3.1 KiB
Markdown
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libgfxinit
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==========
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*libgfxinit* is a graphics initialization (aka modesetting) library
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for embedded environments. It currently supports only Intel hardware,
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more specifically the Intel Core processor line.
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It can query and set up most kinds of displays based on their EDID
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information. You can, however, also specify particular mode lines.
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*libgfxinit* is written in SPARK, an Ada subset with formal verifica-
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tion aspects. Absence of runtime errors can be proved automatically
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with SPARK GPL 2016.
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Building on Linux
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=================
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Prerequisites
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-------------
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For compilation, the GNAT Ada compiler is required. Usual package
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names in Linux distributions are `gcc-ada` and `gnat`.
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Grab the Sources
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----------------
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You'll need *libhwbase* and *libgfxinit*. Best is to clone the reposi-
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tories into a common parent directory (this way *libgfxinit* will know
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where to find *libhwbase*).
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$ mkdir gfxfun && cd gfxfun
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$ git clone https://review.coreboot.org/p/libhwbase.git
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$ git clone https://review.coreboot.org/p/libgfxinit.git
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Configure and Install libhwbase
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-------------------------------
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Both libraries are currently configured by hand-written config files.
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You can either write your own `.config`, link one of the shipped files
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in `configs/`, e.g.:
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$ ln -s configs/linux libhwbase/.config
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or overwrite the config filename by specifying `cnf=<configfile>` on
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the make command line.
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By default most debug messages won't be compiled into the binary. To
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include them into the build, set `DEBUG=1` on the command line or in
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your `.config`.
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Let's install *libhwbase*. We'll need `configs/linux` to build regular
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Linux executables:
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$ cd libhwbase
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$ make DEBUG=1 cnf=configs/linux install
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By default this installs into a new subdirectory `dest`. You can however
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overwrite this decision by specifying `DESTDIR=`.
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Build libgfxinit/`gfx_test`
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---------------------------
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*libgfxinit* is configured and installed in the same manner as de-
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scribed above. You will have to select a configuration matching your
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hardware.
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The makefile knows an additional target `gfx_test` to build a small
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Linux test application:
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$ cd ../libgfxinit
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$ make DEBUG=1 cnf=configs/sandybridge gfx_test
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The resulting binary is `build/gfx_test`.
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Testing libgfxinit on Linux
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===========================
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`gfx_test` sets up its own framebuffer in the *stolen memory*. It
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backs any current framebuffer mapping and contents up first and re-
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stores it before exiting. This works somehow even while the *i915*
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driver is running. A wrapper script `gfxtest/gfx_test.sh` is pro-
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vided to help with the setup. It switches to a text console first
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and tries to unload the *i915* driver. But ignores failures to do
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so (it won't work if you still have any application running that
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uses the gfx driver, e.g. an X server).
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# gfxtest/gfx_test.sh
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If you chose the right config above, you should be presented with a
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nice test image. But please be prepared that your console might be
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stuck in that state afterwards. You can try to run it with *i915*
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deactivated then (e.g. when booting with `nomodeset` in the kernel
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command line or with *i915* blacklisted) and loading it afterwards.
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