linux - 如何加速 Linux 内核重建

Question

调试内核时，我经常只用 make 重建内核。即使我只修改一行，我也必须通过以下所有命令:

make[1]: Nothing to be done for `all'.
  CHK     include/generated/uapi/linux/version.h
make[1]: Nothing to be done for `relocs'.
  CHK     include/generated/utsrelease.h
  CALL    scripts/checksyscalls.sh
  CHK     include/generated/compile.h
  PASYMS  arch/x86/realmode/rm/pasyms.h
  LDS     arch/x86/realmode/rm/realmode.lds
  LD      arch/x86/realmode/rm/realmode.elf
  RELOCS  arch/x86/realmode/rm/realmode.relocs
  OBJCOPY arch/x86/realmode/rm/realmode.bin
  AS      arch/x86/realmode/rmpiggy.o
  CHK     kernel/config_data.h
  LD      arch/x86/realmode/built-in.o
  VDSOSYM arch/x86/vdso/vdso-syms.lds
  VDSOSYM arch/x86/vdso/vdso32-int80-syms.lds
  VDSOSYM arch/x86/vdso/vdso32-syscall-syms.lds
  VDSOSYM arch/x86/vdso/vdso32-sysenter-syms.lds
  VDSOSYM arch/x86/vdso/vdso32-syms.lds
  LD      arch/x86/vdso/built-in.o
  LD      arch/x86/built-in.o
  CC      drivers/gpu/drm/i915/i915_debugfs.o
  LD      drivers/gpu/drm/i915/i915.o
  LD      drivers/gpu/drm/i915/built-in.o
  LD      drivers/gpu/drm/built-in.o
  LD      drivers/gpu/built-in.o
  LD      drivers/built-in.o
  CHK     include/generated/uapi/linux/version.h
make[2]: Nothing to be done for `all'.
make[2]: Nothing to be done for `relocs'.
  LINK    vmlinux
  LD      vmlinux.o
  MODPOST vmlinux.o
  GEN     .version
  CHK     include/generated/compile.h
  UPD     include/generated/compile.h
  CC      init/version.o
  LD      init/built-in.o
  KSYM    .tmp_kallsyms1.o
  KSYM    .tmp_kallsyms2.o
  LD      vmlinux
  SORTEX  vmlinux
  SYSMAP  System.map
  Building modules, stage 2.
  VOFFSET arch/x86/boot/voffset.h
  CC      arch/x86/boot/version.o
  OBJCOPY arch/x86/boot/compressed/vmlinux.bin
  GZIP    arch/x86/boot/compressed/vmlinux.bin.gz
  MKPIGGY arch/x86/boot/compressed/piggy.S
  AS      arch/x86/boot/compressed/piggy.o
  LD      arch/x86/boot/compressed/vmlinux
  ZOFFSET arch/x86/boot/zoffset.h
  OBJCOPY arch/x86/boot/vmlinux.bin
  AS      arch/x86/boot/header.o
  LD      arch/x86/boot/setup.elf
  OBJCOPY arch/x86/boot/setup.bin
  BUILD   arch/x86/boot/bzImage
Setup is 16688 bytes (padded to 16896 bytes).
System is 4107 kB
CRC 9346a092
Kernel: arch/x86/boot/bzImage is ready  (#29)
  MODPOST 664 modules

把上面的命令都传一遍，差不多要1~2分钟，我还是觉得无聊。有什么技巧可以减少内核重建时间吗？

Answer 1

-j 标志将告诉make 并行执行多少个作业。例如。 make -j4 将并行执行四个作业。

关于你应该将-j设置为什么；我不相信有一个直截了当的答案。

这里有一个很好的话题: GNU make: should the number of jobs equal the number of CPU cores in a system?