adoc

Semi automated conversion, in part because Pandoc is kind of buggy for adoc:

Some of the commands were along the lines:

    for f in *.md; do pandoc --atx-headers --base-header-level=3 -o ${f%.md}.adoc --wrap=none $f; done
    sed -Ei '/\[\[.*\]\]/d' *.adoc
    while read -r f; do cat $f; echo; done <f >g

x11.adoc

@@ -0,0 +1,49 @@
+=== X11
+
+Only tested successfully in `x86_64`.
+
+Build:
+
+....
+./build -x
+./run
+....
+
+We don't build X11 by default because it takes a considerable amount of time (~20%), and is not expected to be used by most users: you need to pass the `-x` flag to enable it.
+
+Inside QEMU:
+
+....
+startx
+....
+
+image:x11.png[image]
+
+More details: https://unix.stackexchange.com/questions/70931/how-to-install-x11-on-my-own-linux-buildroot-system/306116#306116
+
+Not sure how well that graphics stack represents real systems, but if it does it would be a good way to understand how it works.
+
+==== X11 ARM
+
+On ARM, `startx` hangs at a message:
+
+....
+vgaarb: this pci device is not a vga device
+....
+
+and nothing shows on the screen, and:
+
+....
+grep EE /var/log/Xorg.0.log
+....
+
+says:
+
+....
+(EE) Failed to load module "modesetting" (module does not exist, 0)
+....
+
+A friend told me this but I haven't tried it yet:
+
+* `xf86-video-modesetting` is likely the missing ingredient, but it does not seem possible to activate it from Buildroot currently without patching things.
+* `xf86-video-fbdev` should work as well, but we need to make sure fbdev is enabled, and maybe add some line to the `Xorg.conf`