立你斯學習記錄

Chapter 9: You've made a mess of it

         第9章: 你把程式弄的亂七八糟了

That's OK, we all do.  You've probably been told by your long-time Unix user helper that "GNU emacs" automatically formats the C sources for you, and you've noticed that yes, it does do that, but the defaults it uses are less than desirable (in fact, they are worse than random typing - an infinite number of monkeys typing into GNU emacs would never make a good program).

沒關係，我們都會遇到這種問題。可能有unix老手已經告訴過你 "GNU emacs" 可以自動的幫你重排C的程式碼，而你也發現它的確會做，但是它的預設值有點令人不滿意 (事實上，這些值還比打字亂打糟糕 - 在GNU emacs上任意的亂打還是造不出好程式的) 。

So, you can either get rid of GNU emacs, or change it to use saner values.  To do the latter, you can stick the following in your .emacs file:

所以，你可以把GNU emacs丟掉，或者設定一些較合理的預設值。後者可以把下面這些碼放到你的 .emacs檔達成：

(defun linux-c-mode ()

  "C mode with adjusted defaults for use with the Linux kernel."

  (interactive)

  (c-mode)

  (c-set-style "K&R")

  (setq tab-width 8)

  (setq indent-tabs-mode t)

  (setq c-basic-offset 8))

This will define the M-x linux-c-mode command.  When hacking on a module, if you put the string -*- linux-c -*- somewhere on the first two lines, this mode will be automatically invoked. Also, you may want to add

這樣定義了 M-x linux-c-mode 指令。當你 hack 某個模組時，如果你在前兩行的任意地方放 -*- linux-c -*- 這個字串，這個模式就 會自動的起動。同時，你也可能想要加這行：

(setq auto-mode-alist (cons '("/usr/src/linux.*/.*\\.[ch]$" . linux-c-mode)

            auto-mode-alist))

to your .emacs file if you want to have linux-c-mode switched on automagically when you edit source files under /usr/src/linux.

到你的 .emacs檔去，如果當你編輯/usr/src/linux下的程式檔的時後，想讓linux-c-mode自動起動的話。

But even if you fail in getting emacs to do sane formatting, not everything is lost: use "indent".

不過僅管你還是不能利用emacs作合理的重排的話，你還沒絕望：使用 "indent"。

Now, again, GNU indent has the same brain-dead settings that GNU emacs has, which is why you need to give it a few command line options.

However, that's not too bad, because even the makers of GNU indent recognize the authority of K&R (the GNU people aren't evil, they are just severely misguided in this matter), so you just give indent the options "-kr -i8" (stands for "K&R, 8 character indents"), or use "scripts/Lindent", which indents in the latest style.

這裡又遇到同樣的問題。GNU indent和GNU emacs有同樣的白癡設定，這就是為什麼你須要給它一些命令列選項的原因。還好，這不會太麻煩，因為連GNU indent的作者也體認到K&R的權威性 (GNU的人不壞，他們在這方面只是被嚴重的誤導了罷了) ，所以你只要給indent這樣的選項 "-kr -i8"即可 (表示 "K&R，8格的縮排")。

"indent" has a lot of options, and especially when it comes to comment re-formatting you may want to take a look at the man page.  But remember: "indent" is not a fix for bad programming.

"indent" 有許多的選項，特別是預到重排註解的時候，你可能需要看一下使用手冊. 不過要記得："indent" 不是修理不良程式碼的工具。

         Chapter 10: Kconfig configuration files

For all of the Kconfig* configuration files throughout the source tree, the indentation is somewhat different.  Lines under a "config" definition are indented with one tab, while help text is indented an additional two spaces.  Example:

config AUDIT

    bool "Auditing support"

    depends on NET

    help

      Enable auditing infrastructure that can be used with another

      kernel subsystem, such as SELinux (which requires this for

      logging of avc messages output).  Does not do system-call

      auditing without CONFIG_AUDITSYSCALL.

Features that might still be considered unstable should be defined as dependent on "EXPERIMENTAL":

config SLUB

    depends on EXPERIMENTAL && !ARCH_USES_SLAB_PAGE_STRUCT

    bool "SLUB (Unqueued Allocator)"

    ...

while seriously dangerous features (such as write support for certain filesystems) should advertise this prominently in their prompt string:

config ADFS_FS_RW

    bool "ADFS write support (DANGEROUS)"

    depends on ADFS_FS

    ...

For full documentation on the configuration files, see the file Documentation/kbuild/kconfig-language.txt.