MIT6.828課程JOS在macOS下的環境配置

本文將介紹如何在macOS下配置MIT6.828 JOS實驗的環境。

寫JOS以前，在網上搜尋JOS的開發環境，不少博客和文章都提到「不是32位linux就很差配置，會浪費大量時間在配置環境」上之類的論調。故前期開發直接使用了32位ubuntu系統，並作了共享文件系統，背景開一個ubuntu虛擬機進行編譯。
最近實在沒法忍受背景開虛擬機那恐怖的耗電量和發熱量，嘗試將開發環境移到macOS下，竟發現很是的簡單。

Tools we need

在搭建環境以前，首先macOS上須要有如下兩個工具：

• Homebrew Homebrew — The missing package manager for macOS
• MacPorts The MacPorts Project -- Home

運行JOS

• QEMU

  有了Homebrew，直接利用brew安裝便可安裝（自動安裝依賴庫）

  $brew install qemu

• 將kernel.img與fs.img放在目標目錄下 （也能夠在其餘位置，爲了下面的Makefile好寫）

  .
  ├── Makefile
  ├── fs.img
  └── kernel.img

• 書寫Makefile

  QEMU=/usr/local/Cellar/qemu/2.10.0/bin/qemu-system-i386 # path to qemu
  run:
    $(QEMU) -drive file=./kernel.img,index=0,media=disk,format=raw -serial mon:stdio -vga std -smp 1 -drive file=./fs.img,index=1,media=disk,format=raw

編譯JOS

• i386-elf-gcc

  利用Macports來安裝i386-elf-gcc

  $ sudo port -v selfupdate
  $ sudo port install i386-elf-gcc

  Macports會幫你下載源碼，編譯（很是漫長）

• 修改Makefile中的一些內容

  diff --git a/GNUmakefile b/GNUmakefile
  index adc693e..60fe010 100644
  --- a/GNUmakefile
  +++ b/GNUmakefile
  @@ -33,15 +33,15 @@ TOP = .
  
   # try to infer the correct GCCPREFIX
   ifndef GCCPREFIX
  -GCCPREFIX := $(shell if i386-jos-elf-objdump -i 2>&1 | grep '^elf32-i386$$' >/dev/null 2>&1; \
  -       then echo 'i386-jos-elf-'; \
  +GCCPREFIX := $(shell if i386-elf-objdump -i 2>&1 | grep '^elf32-i386$$' >/dev/null 2>&1; \
  +       then echo 'i386-elf-'; \
          elif objdump -i 2>&1 | grep 'elf32-i386' >/dev/null 2>&1; \
          then echo ''; \
          else echo "***" 1>&2; \
          echo "*** Error: Couldn't find an i386-*-elf version of GCC/binutils." 1>&2; \
  -       echo "*** Is the directory with i386-jos-elf-gcc in your PATH?" 1>&2; \
  +       echo "*** Is the directory with i386-elf-gcc in your PATH?" 1>&2; \
          echo "*** If your i386-*-elf toolchain is installed with a command" 1>&2; \
  -       echo "*** prefix other than 'i386-jos-elf-', set your GCCPREFIX" 1>&2; \
  +       echo "*** prefix other than 'i386-elf-', set your GCCPREFIX" 1>&2; \
          echo "*** environment variable to that prefix and run 'make' again." 1>&2; \
          echo "*** To turn off this error, run 'gmake GCCPREFIX= ...'." 1>&2; \
          echo "***" 1>&2; exit 1; fi)

• 修改.deps中一些內容

  刪除fsformat的依賴檢查

  obj/fs/: fs/fsformat.c

• 修改配置文件中的qemu參數

  QEMU=/usr/local/Cellar/qemu/2.10.0/bin/qemu-system-i386

編譯運行JOS