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Portability-matters.md (3468B)

    

  1. ---
  2. date: 2017-11-13
  3. layout: post
  4. title: Portability matters
  5. tags: [portability, philosophy]
  6. ---
  8. There are many kinds of "portability" in software. Portability refers to the
  9. relative ease of "porting" a piece of software to another system. That
  10. platform might be another operating system, another CPU architecture, another
  11. web browser, another filesystem... and so on. More portable software uses the
  12. limited subset of interfaces that are common between systems, and less portable
  13. software leverages interfaces specific to a particular system.
  15. Some people think that portability isn't very important, or don't understand the
  16. degree to which it's important. Some people might call their software portable
  17. if it works on Windows and macOS - they're wrong. They might call their software
  18. portable if it works on Windows, macOS, and Linux - but they're wrong, too.
  19. Supporting multiple systems does not necessarily make your software portable.
  20. What makes your software portable is *standards*.
  22. The most important standard for software portability is POSIX, or the **Portable
  23. Operating System Interface**. Significant subsets of this standard are supported
  24. by many, many operating systems, including:
  26. - Linux
  27. - *BSD
  28. - macOS
  29. - Minix
  30. - Solaris
  31. - BeOS
  32. - Haiku
  33. - AIX
  35. I [could go
  36. on](https://en.wikipedia.org/wiki/POSIX#POSIX-oriented_operating_systems).
  37. Through these operating systems, you're able to run POSIX compatible code on a
  38. large number of CPU architectures as well, such as:
  40. - i386
  41. - amd64
  42. - ARM
  43. - MIPS
  44. - PowerPC
  45. - sparc
  46. - ia64
  47. - VAX
  49. Again, I could go on. Here's the point: by supporting POSIX, your software runs
  50. on basically every system. *That's* what it means to be portable - standards.
  51. So why is it important to support POSIX?
  53. First of all, if you use POSIX then your software runs on just about anything,
  54. so lots of users will be available to you and it will work in a variety of
  55. situations. You get lots of platforms for free (or at least cheap). But more
  56. importantly, *new platforms* get your software for free, too.
  58. The current market leaders are not the end-all-be-all of operating system
  59. design - far from it. What they have in their advantage is working well enough
  60. and being incubent. Windows, Linux, and macOS are still popular for the same
  61. reason that legislator you don't like keeps getting elected! However, new
  62. operating systems have a fighting chance thanks to POSIX. All you have to do to
  63. make your OS viable is implement POSIX and you will immediately open up
  64. hundreds, if not thousands, of potential applications. Portability is important
  65. for innovation.
  67. The same applies to other kinds of portability. Limiting yourself to standard
  68. browser features gives new browsers a chance. Implementing standard networking
  69. protocols allows you to interop with other platforms. I'd argue that failing to
  70. do this is *unethical* - it's just another form of vendor lock-in. This is why
  71. Windows does not support POSIX.
  73. This is also why I question niche programming languages like Rust when they
  74. claim to be suited to systems programming or even kernel development. That's
  75. simply not true when they only run on a small handful of operating systems and
  76. CPU architectures. C runs on *literally* everything.
  78. In conclusion: use standard interfaces for your software. That guy who wants to
  79. bring new life to that old VAX will thank you. The authors of
  80. [servo](https://servo.org/) thank you. *You* will thank you when your
  81. circumstances change in 5 years.