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254c8bf42e
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
48 lines
1.9 KiB
Plaintext
48 lines
1.9 KiB
Plaintext
=== Run on host
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This method runs the kernel modules directly on your host computer without a VM, and saves you the compilation time and disk usage of the virtual machine method.
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It has however severe limitations, and you will soon see that the compilation time and disk usage are well worth it:
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* can't control which kernel version and build options to use. So some of the modules will likely not compile because of kernel API changes, since https://stackoverflow.com/questions/37098482/how-to-build-a-linux-kernel-module-so-that-it-is-compatible-with-all-kernel-rele/45429681#45429681[the Linux kernel does not have a stable kernel module API].
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* bugs can easily break you system. E.g.:
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** segfaults can trivially lead to a kernel crash, and require a reboot
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** your disk could get erased. Yes, this can also happen with `sudo` from userland. But you should not use `sudo` when developing newbie programs. And for the kernel you don't have the choice not to use `sudo`
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** even more subtle system corruption such as https://unix.stackexchange.com/questions/78858/cannot-remove-or-reinsert-kernel-module-after-error-while-inserting-it-without-r[not being able to rmmod]
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* can't control which hardware is used, notably the CPU architecture
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* can't step debug it with GDB easily
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Still interested?
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....
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cd kernel_module
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./make-host.sh
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....
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If the compilation of any of the C files fails because of kernel or toolchain differences that we don't control on the host, just rename it to remove the `.c` extension and try again:
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....
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mv broken.c broken.c~
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./build_host
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....
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Once you manage to compile, and have come to terms with the fact that this may blow up your host, try it out with:
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....
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sudo insmod hello.ko
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# Our module is there.
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sudo lsmod | grep hello
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# Last message should be: hello init
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dmest -T
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sudo rmmod hello
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# Last message should be: hello exit
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dmesg -T
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# Not present anymore
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sudo lsmod | grep hello
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....
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