[muflon]

"Without its software, a computer is basically a useless lump of metal. With its software, a computer can store, process, and retrieve information; display multimedia documents; search the Internet; and engage in many other valuable activities to earn its keep. Computer software can be divided roughly into two kinds: system programs, which manage the operation of the computer itself, and application programs, which perform the actual work the user wants.

The most fundamental system program is the operating system, which controls alll the computer's resources and provides the base upon which the application programs can be written.

[...]
On top of the operating system is the rest of the system software. Here we find the command interpreter (shell), window systems, compilers, editors, and similar application-independent programs. It is important to realize that these programs are definitely not part of the operating system, even though they are typically supplied by the computer manufacturer.

This is a crucial, but subtle, point.

The operating system is that portion of the software that runs in kernel mode or supervisor mode. It is protected from user tampering by the hardware (ignoring for the moment some of the older microprocessors that do not have hardware protection at all).

Compilers and editors run in user mode.

If a user does not like a particular compiler, he is free to write his own if he so chooses; he is not free to write his own disk interrupt handler, which is part of the operating system and is normally protected by hardware against attempts by users to modify it.

Finally, above the system programs come the application programs. These programs are purchased or written by the users to solve their particular problems, such as word processing, spreadsheets, engineering calculations, or game playing."

Tanenbaum A. S., Woodhull A. S., Operating Systems: Design and Implementation, 2nd Edition, Prentice Hall, 1997, p. 1, 3.


For those who want to know more about NetBSD internals.


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A) NetBSD - papers, publications
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[1] Balmer M., Lua in the NetBSD Kernel, 2012 - [pdf] [u2]

[2] Balmer M., Ierusalimschy R., Moura A. L., Neto L. V., Scriptable Operating Systems with Lua, [ACM] 2014 - [pdf] [u2]

[3] Brown A. B., Seltzer M. I., Operating System Benchmarking in the Wake of Lmbench: A Case Study of the Performance of NetBSD on the Intel x86 Architecture, 2002 - [pdf] [u1]

[4] Chung S. W., The Design of the NetBSD I/O Subsystems, 2003, - [pdf] [u1]

[5] Cormack J., Kantee A., Rump Kernels No OS? No Problem!, 2014 - [pdf]

[6] Cranor C. D., Parulkar G. M., The UVM Virtual Memory System, 1999 - [pdf] [u3]

[7] Crooks A., Package Views - a more flexible infrastructure for third-party software, 2002 - [pdf]

[8] Crooks A., Feyrer H., The pkgsrc guide - Documentation on the NetBSD packages system, The NetBSD Foundation 2014 - [pdf]

[9] Crooks A., Kantee A., ReFUSE: Userspace FUSE Reimplementation Using puffs, 2007 - [pdf]

[10] Dreyfus E., Binary compatibility on NetBSD, 2014, - [pdf] [presentation] [u1]

[11] Efrat E., Recent Security Enhancements in NetBSD, 2006 - [pdf]

[12] Feyrer H., System Administration Training in the Virtual Unix Lab, 2008 - [pdf]

[13] Green M., Mewburn L., build.sh: Cross-building NetBSD, 2003 -[pdf]

[14] Hamsik A., The NetBSD Logical Volume Manager, 2009 - [pdf]

[15] Hoka A., Flash and NAND Subsystem for NetBSD, 2011 - [pdf] [u3]

[16] Kantee A., Flexible operating system internals: The design and implementation of the anykernel and rump kernels, 2012 - [pdf] [u2]

[17] Kantee A., Ysmal A., Fs-utils: File Systems Access Tools for Userland, 200 - [pdf]

[18] Kantee A., Rump File Systems: Kernel Code Reborn, 2009 - [pdf] [u2]

[19] Kesteloot L., Porting BSD UNIX to a New Platform, 1995 - [pdf] [u1]

[20] Kunz J., Writing Drivers for NetBSD, 2003 - [pdf]

[21] Kuparinen M., Xen Disk I/O Benchmarking: NetBSD dom0 vs Linux dom0, 2005 - [html] [u1]

[22] Lehey G., Debugging Kernel Problems, Edition for BSDCan 2006 - [pdf] [u3]

[23] Lupi F., The NetBSD Operating System - A Guide, 2003 - [pdf]

[24] McGarry G., Benchmark Comparison of NetBSD 2.0 and FreeBSD 5.3, 2004 - [pdf] [u1]

[25] McGarry G., Benchmark Comparison of NetBSD 3.0, FreeBSD 6.0 and Fedora Core 4, 2006 - [pdf] [u1]

[26] Mewburn L., The Design and Implementation of the NetBSD rc.d system, 2001 -[pdf]

[27] Neto L. V., NPF Scripting with Lua. Scripting the NetBSD Packet Filter with Lua, 2014 - [pdf] [u2]

[28] Nishimura T., 64bit SMP NetBSD OS Porting for TILE-Gx VLIW Many-Core Processor, 2013 - [pdf] [u3]

[29] Rasiukevicius M., NPF – the packet filter of NetBSD, 2012 - [pdf]

[30] Rasiukevicius M., Thread scheduling and related interfaces in NetBSD 5.0, 2009 - [pdf]

[31] Steinmann A., Single User Secure Shell, 2005 - [pdf] [u3]

[32] Thorpe J. R., A Machine-Independent DMA Framework for NetBSD, 1998? - [pdf]

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B) BSDTalk Interviews:
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[1] bsdtalk021 - Interview with Stephen Jones [smj] of SDF (March 1, 2006) [mp3] [u1]

[2] bsdtalk045 - Interview with NetBSD Developer Mouse (May 17, 2006) - End of life for the NetBSD 1.6 branch. Time to move on. [mp3] [u3]

[3] bsdtalk057 - Interview with Massimiliano Stucchi (July 24, 2006) - NetBSD 3.0.1 Released. [mp3] [u3]

[4] bsdtalk064 - Interview with NetBSD Developer Jason Thorpe (September 11, 2006) - [mp3] [u3]

[5] bsdtalk070 - Interview with NetBSD Developer Tim Rightnour (September 27, 2006) [mp3] [u3]

[6] bsdtalk089 - NetBSD Release Engineer Jeff Rizzo (December 29, 2006) [mp3] [u3]

[7] bsdtalk100 - NetBSD Developer Lubomir Sedlacik (February 15, 2007) [mp3] [u3]

[8] bsdtalk171 - Andrew Doran from the NetBSD Project (March 6, 2009) [mp3] [u1]

[9] bsdtalk215 - NetBSD project update (May 23, 2012) [mp3] [u1]