没有目录为/usr/src/linux-2.x/include/asm-i386/unistd.h

Question

I'm trying to build a kernel as a hobby project by following the project part given in the book Operating System Concepts by Silberschatz, Galvin and Gagne. The book states:

The system call numbers for recent versions of the Linux kernel are listed in /usr/src/linux-2.x/include/asm-i386/unistd.h.

But I can not find this directory. There is no directory like linux-2.x ; all are of the form linux-3.x .

Answer 1

These headers get automatically generated nowadays and the tables for that are in eg: linux-4.4.5/arch/x86/entry/syscalls/ . Depending on the distribution you might need to install the kernel headers separately, eg: with Ubuntu (packet linux-headers-$VERSION . Version must fit the kernel version!). I found them installed at /usr/src/linux-headers-3.13.0-37-generic/arch/x86/include/generated/asm/ (with Linux Mint which is based on Ubuntu) . The headers there get included from the regular unistd.h to be found (again for x86) in /usr/src/linux-headers-3.16.0-37/arch/x86/include/asm/unistd.h . (actual version of kernel may vary).

Last kernel with major version 2 is 2.6.39.4 from August 2011. You can try it but it won't boot on hardware more modern than an old Pentium. If you have such an old machine or have a machine with enough horsepower to run a virtual Pentium machine--go for it. But I would recommend to upgrade you book instead.

If you are wondering why you (and I) have a version 3 instead of the most recent 4.9: if your hardware runs with it, it has no grave security related bugs and you don't need any of the things in the most recent kernel, then use the one your distribution gave you, they know what they are doing (he said boldly).