add post: lkmpg

content/blog/linux-lkmpg-milkv.md

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++++
+title = "Following the Linux Kernel Module Programming Guide with RISC-V Milkv Duo embedded board"
+date = 2024-01-06 13:27:00
+draft = false
+
+[taxonomies]
+categories = ["embedded-linux"]
+tags = ["embedded-linux", "linux", "linux drivers", "milkv-duo"]
+
+[extra]
+lang = "en"
+toc = true
+comment = false
+copy = true
+math = false
+mermaid = false
+outdate_alert = false
+outdate_alert_days = 120
+display_tags = true
+truncate_summary = false
++++
+
+We saw in [this post](@/blog/linux-embedded-howto.md) that [The Linux Kernel Module Programming Guide](https://sysprog21.github.io/lkmpg/) is a great resource when learning Linux Device Drivers. It however takes a self-compiled route with the modules developed and run directly on the host system. For GPIO examples the Raspberry PI is used.
+
+In this article we shall see how to adopt the guide to learn with the [Milk-V Duo](https://milkv.io/duo) board. Here we assume you use the vanilla Buildroot [repo](https://github.com/milkv-duo/milkv-duo-buildroot) for building the system image.
+
+## Adapting the Makefile
+
+As mentioned above, the modules are selfcompiled to run locally on the host system. To make them run on our dev board we need to modify the Makefile. The C source file is left untouched.
+
+```Makefile
+CC = $(CROSS_COMPILE)gcc
+
+obj-m := hello.o
+KDIR := /home/<user>/milkv/milkv-duo-buildroot/output/build/linux-duo-linux-5.10.4
+
+all:
+	$(MAKE) -C $(KDIR) M=$(PWD)
+
+clean:
+	$(MAKE) -C $(KDIR) M=$$PWD clean
+
+```
+
+Be sure to adapt the `KDIR` path to suite your system's location. Also make note to change `hello.o` to whatever you named your C source file.
+
+## Changing the GPIO directives
+
+In the chapter [#detecting-button-presses](https://sysprog21.github.io/lkmpg/#detecting-button-presses), they use the Raspberry PI which is based on Cortex-A architecture. Our RISC-V board uses different GPIO naming scheme, and we need to adapt accordingly...
+
+TODO
+