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+---
+title: RISC-V Bootstrapping in Guix and Live-Bootstrap
+subtitle: Status report for 2023, and what's coming up next
+
+license: CC-BY-SA
+author: Ekaitz Zárraga
+links-as-notes: true
+lang: spanish
+polyglossia-lang:
+    name: english
+how-to: pandoc -f markdown+smart -t beamer contents.md -o beamer.pdf --pdf-engine=xelatex --template=template.tex
+convert-img: inkscape IN.svg --export-filename OUT.png --export-type=png --export-background-opacity=0.0 # NOT NEEDED!
+header-includes:
+    - \usepackage{multicol}
+    - \newcommand{\hideFromPandoc}[1]{#1}
+    - \hideFromPandoc{
+        \let\Begin\begin
+        \let\End\end
+      }
+...
+
+## Before we start
+
+If you want details and don't mind reading large text walls full of
+nitty-gritty details, you can leave this talk and read [all the blogposts I did
+on the process](https://ekaitz.elenq.tech/tag/bootstrapping-gcc-in-risc-v.html)
+
+**You can still stay here and smile, too.**
+
+## Who I am
+
+- Telecommunication engineer (EEE equivalent)
+- Freelance engineer/programmer at [ElenQ.Tech](https://elenq.tech)
+- Guix user and contributor
+- You might remember me from my talk last year:
+  *"Bringing RISC-V to Guix's bootstrap"*
+
+
+
+## Context
+
+- In 2021 [NlNet][nlnet-grant-i] funded me to do some bootstrapping work: I
+  backported RISC-V support to GCC 4.6.4 from 7.5, and to our TinyCC-Boot from
+  upstream TinyCC. These were fundamental points in our bootstrap chain.
+- I explained that in [FOSDEM 2023][fosdem-2023].
+
+[nlnet-grant-i]: https://nlnet.nl/project/GNUMes-RISCV/index.html
+[fosdem-2023]: https://archive.fosdem.org/2023/schedule/event/guixriscv/
+
+\hfill ![\ ](img/nlnet.svg){height=25px}\
+\hfill ![\ ](img/NGIAssure.svg){height=15px}
+
+
+## Intro
+
+- The work wasn't finished so I asked for a [second grant to
+  NlNet][nlnet-grant-ii].
+- I was tired of the previous effort and I needed help. I decided to bring more
+  people to the project:
+    - **Andrius Štikonas**: Involved in `live-bootstrap`, `stage-0` and the
+      related projects. Has the context awareness I lack.
+    - **Janneke**: `Mes` maintainer and author, `TinyCC-boot` maintainer and
+      `guix` contributor. All these projects are structural to the
+      bootstrapping process.
+    - More people
+- My goal was to pay people for their good work, using the success of my
+  previous effort as a lever to get funded.
+
+[nlnet-grant-ii]: https://nlnet.nl/project/GNUMes-RISCV-bootstrap/
+
+\hfill ![\ ](img/nlnet.svg){height=25px}\
+\hfill ![\ ](img/NGIAssure.svg){height=15px}
+
+
+# In pictures
+
+## Bootstrapping process - Before
+
+\Begin{multicols}{2}
+
+- Colors represent RISC-V support:
+    - **\textcolor{red}{RED}**: no RISC-V support
+    - **\textcolor{orange}{ORANGE}**: some RISC-V support
+    - **\textcolor{green}{GREEN}**: full RISC-V support
+- **TinyCC-boot** and **GCC (old)** are **\textcolor{red}{RED}**.
+\vfill
+
+\columnbreak
+
+![\ ](img/Bootstrapping_simple.svg)
+
+\End{multicols}
+
+## Bootstrapping process - After the Backport (2022)
+
+\Begin{multicols}{2}
+
+- **Arrows** are still **\textcolor{red}{RED}**
+- At that time I didn't know **TinyCC** was **\textcolor{orange}{ORANGE}**,
+  that was discovered later
+- **GCC (old)** was actually **\textcolor{green}{GREEN}ER** than I thought
+\vfill
+
+\columnbreak
+
+![\ ](img/Bootstrapping_with_backport.svg)
+
+\End{multicols}
+
+## Bootstrapping process - Now
+
+\Begin{multicols}{2}
+- **TinyCC-Boot** is **\textcolor{green}{GREEN}** now
+- The **\textcolor{green}{GREEN}** rectangle is included in `Guix` and
+  `live-bootstrap`
+- **GCC (old)** is **\textcolor{green}{GREEN}** now: Tested in Debian in real
+  RISC-V hardware.
+\vfill
+
+\columnbreak
+
+![\ ](img/Bootstrapping_now.svg)
+
+\End{multicols}
+
+## Bootstrapping process - Future
+
+\Begin{multicols}{2}
+- **\textcolor{red}{->} TinyCC** requires changes in MesLibC
+- **\textcolor{red}{->} GCC (old)**:
+    - requires `make`
+    - TinyCC claims to be able to build GCC 4, but we didn't test that (i386
+      bootstrap uses GCC 2.95 in between).
+- **\textcolor{red}{->} GCC** should *just work*
+- A powerful `libc` is needed, built with TinyCC, which doesn't support
+  Extended Assembly.
+\vfill
+
+\columnbreak
+
+![\ ](img/Bootstrapping_now.svg)
+
+\End{multicols}
+
+
+# Questions?
+
+## 
+
+<!-- EXTRA -->
+
+# Limitations of the backport
+
+## TinyCC
+
+- I only tested the backend, in an emulated environment, using a using TinyCC
+  as a cross-compiler
+- I tested on **GLibC**, but in the bootstrapping process it uses **MesLibC**,
+  a minimal **LibC**, part of Mes.
+- **TinyCC-Boot** is in fact compiled several times (up to 6) with different
+  features (using conditional compilation via macro definitions like `-D...`).
+    - In a cross compiled environment this is not possible to test
+- I didn't test the TinyCC **RISC-V assembler**, which happened to be
+  unimplemented (yeah... LOL), and it's needed for the **LibC**.
+
+## TinyCC
+
+![TinyCC-Boot bootstrapping process](img/tcc-boot.svg)
+
+## GCC
+
+- I tested it as a Cross-Compiler, so only the backend was tested. Again, no
+  bootstrap[^gcc-bootstrap].
+- It never compiled itself
+- I didn't work on the C++ support
+
+[^gcc-bootstrap]: GCC has a bootstrap process that checks if the compiler works
+    correctly. First, it's compiled with your compiler of choice. Then, the
+    resulting binary is used to compile the GCC codebase again. The result of
+    that compiles GCC again. Then the binaries are compared, to make sure they
+    are identical. This can't be done in a cross-compiled environment, for
+    obvious reasons.
+
+# The work
+
+## TinyCC-Boot
+
+We focused on this, and let the other projects be carried by this effort.
+
+- Andrius and I spent many nights debugging crazy things in here.
+- TinyCC's codebase is hard to read
+- Many errors we got were not reproducible using a TinyCC compiled with GCC, so
+  we needed to build it from MesCC, which is very slow
+- MesCC doesn't provide very helpful debug symbols
+- We learned many things as we went
+
+> I wouldn't have the energy to make this without Andrius.
+
+## TinyCC-Boot - Crazy things
+
+1. Body is never executed:
+
+    ``` c
+    if ( x < 8 ) {
+        // body
+    }
+    ```
+2. `A << 20 >> 20`
+3. `__global_pointer$ is not a valid symbol`
+4. Assembler uses a weird syntax and doesn't support Extended Assembly
+5. `cannot cast from/to void`
+6. And segfaults, segfaults everywhere!
+
+[Read more about them here](https://ekaitz.elenq.tech/bootstrapGcc8.html)
+
+## TinyCC-Boot - Results
+
+We finally managed to bootstrap TinyCC-Boot.
+
+- Andrius included the [build recipe in `live-bootstrap`](https://github.com/fosslinux/live-bootstrap/blob/master/steps/tcc-0.9.26/pass1.kaem)
+- I did the [`guix` recipe](https://issues.guix.gnu.org/68222)
+
+## GNU Mes
+
+The problems we found in **TinyCC-Boot** made us improve Mes in several ways:
+
+- **MesCC**, the C compiler, had some limitations that were unnoticed in the i386
+  bootstrap that appeared in RISC-V: faulty `switch-case`s, wrong `struct`
+  initializations, some integer weirdness...
+- **MesLibC**, had to be split for our TinyCC as it doesn't support Extended
+  Assembly, and it also needed some extra tweaks: `char` signedness, `va_args`
+  support, build script support for the changes...
+
+> Having Janneke with us made the process very smooth.
+
+
+## GCC
+
+- We compiled GCC with itself in a Debian machine in real RISC-V hardware
+- Including C++ support
+- [Only needed a few commits!](https://github.com/ekaitz-zarraga/gcc/compare/working-compiler...riscv)
+- Guix recipe is pending, as we need to fix other steps to be able to add this:
+  `make`, a proper `libc`, TinyCC...
+
+
+# Last words
+
+## Last words
+
+- People is important: I felt alone, and I didn't know how to continue. If I
+  had to spend another year working alone I would've just rejected the project.
+  **Bringing people gave me energy, knowledge and emotional support**
+
+- Money is important: thanks to NlNet I had the chance to pay people for their
+  work and buy some hardware. Covering people's basic needs is fundamental.
+  **Getting paid makes people independent, so they can focus on what they are
+  good at instead of struggling to survive**
+
+## So
+
+- Thanks, Andrius and Janneke
+- Thanks, NlNet
+- And...
+
+# Thank you
+
+## Contact and take part
+
+- Email me: <ekaitz@elenq.tech>
+- Relevant IRC channels: `#bootstrappable`, `#guix`, `#guix-risc-v`
+