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content/2014/01/14/self-hosting-fedora-base.md

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+title = "Self Hosting Fedora Base"
+date = 2014-01-14T16:15:52+00:00
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+If you want to bootstrap a distribution or want to rebuild it from the sources (SRPMS) to get the same 
+binaries (think CentOS), you have to build the build tools and rebuild them with the built build tools, 
+which have to be built with other build tools…
+
+My goal for a self-hosting Fedora Base is to reduce the number of packages to do such a rebuild.
+
+<!-- more -->
+
+The first step is to get the packages to build the most important component for a linux distribution - the kernel.
+
+To get those packages, Phil Knirsch wrote a small python script, which calls `repoquery`.
+I extended this script to output graphviz .dot formatted files. 
+
+The first run gives us [1806 packages](https://harald.fedorapeople.org/kernel-br-all.txt), with which you could build 
+the tools to build the tools to […] build the kernel, if you manage to break the dependency cycle, etc. 
+
+If you want to display this beast with e.g. "sfdp" and "gvmap" from the graphviz suite, this will give you a monster graph.
+
+[<img alt="Self-Hosting kernel build requirements" src="https://harald.fedorapeople.org/kernel-br-all.png" height="333" width="800" />](https://harald.fedorapeople.org/kernel-br-all.svg)
+Self-Hosting kernel build requirements
+
+This was generated with the [kernel-br-all.dot](https://harald.fedorapeople.org/kernel-br-all.dot) file and the command:
+```console
+$ START=7; cat kernel-br-all.dot | \
+ sfdp -Gstart=$START -Goverlap=prism | \
+ gvmap -e -d $START | \
+ neato -Gstart=$START -n2 -Ecolor=#44444455 -Tsvg \
+> kernel-br-all.svg
+```
+
+My next step was to identify the source of weird build requirements like `qt`, `kdelibs` or `wayland`. 
+So I build a list of packages, which might be removed from the build requirements, because they only build documentation
+or willingly add a build requirement to a graphical component like X, wayland or a GUI.
+
+After filtering those with [the python script](https://harald.fedorapeople.org/buildreq.py), the resulting graph was 
+mainly dominated by perl packages, so I just merged them in one "perl" node. The graph from this is almost readable. 
+
+[<img alt="Reduced Self-Hosting kernel build requirements" src="https://harald.fedorapeople.org/kernel-br-reduced.png" height="525" width="800" />](https://harald.fedorapeople.org/kernel-br-reduced.svg)
+Reduced Self-Hosting kernel build requirements
+
+`graphviz` comes with `tred`, which reduces the graph, so that at least one path leads from X to Y.
+With this reduction we get a nice graph generated from
+[kernel-br-reduced.dot](https://harald.fedorapeople.org/kernel-br-reduced.dot) by:
+
+```console
+$ START=7; tred kernel-br-reduced.dot | \
+ sfdp -Gstart=$START -Goverlap=prism | \
+ gvmap -e -d $START | \
+ neato -Gstart=$START -n2 -Ecolor=#44444455 -Tsvg \
+ > kernel-br-reduced-tred.svg
+```
+
+Now, most of the build requirements are missing, but one path, so you can at least find **one** package,
+which requires a specific package. All the red nodes in the graph are the build requirements, for which no
+build requirements were added. So the strategy should be to get rid of those, or make sure they don't pull in the #
+complete distribution. We might want to use the pre-built documentation shipped with the package or have a separate 
+documentation build phase with the same source. For other packages, we might have to split out the GUI components. 
+If you have other ideas, I am happy to get to know them.
+
+**Conclusion: 188 packages plus all the perl packages could form a basic buildroot to build itsself.
+To achieve this, we have to take care of those 56 red packages, that these are not used.** 
+
+The list of the 65 spec files with the build requirements to ifdef can be found here: 
+[http://harald.fedorapeople.org/bootstrap-not-needed-deps.txt](https://harald.fedorapeople.org/bootstrap-not-needed-deps.txt)
+ 
+[<img alt="" src="https://harald.fedorapeople.org/kernel-br-reduced-tred.svg" width="800" />](https://harald.fedorapeople.org/kernel-br-reduced-tred.svg)
+Reduced Build Requirements for the package kernel

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content/2014/_index.md

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