I've spent a good chunk of the day trying to compile a new kernel for my Debian install in order to test out a sound card patch. There's a lovely reddit thread here which descibes a potential patch for using a Sound Blaster Zx under Linux.

When attempting to build the kernel with this patch, I came across the following missing package dependencies when building on Debian 9:

• bison
• flex
• libelf-dev

The last one caused me a lot of pain due to the following compilation errors:

CC /home/mmallin/src/kernel/linux-4.19.13/tools/objtool/special.o In file included from /usr/include/gelf.h:32:0, from elf.h:22, from check.h:22, from builtin-orc.c:29: /usr/include/libelf.h:46:4: error: unknown type name ‘Elf32_Word’ Elf32_Word ch_type; / Compression format. / ^~~~~~~~~~

Turns out according to this thread it is my CPATH environment variable causing issues with the libelf header inclusion. Clearing the environment variable fixed the above compilation issue.