FreeBSD Kernel Games

1:Back Up Your Working Kernel

# cp -Rp /boot/kernel /boot/kernel.good

2:保存 Kernel 配置文件

# cd /usr/src/sys/amd64/conf
# mkdir /root/kernels
# cp GENERIC /root/kernels/MYKERNEL
# ln -s /root/kernels/MYKERNEL

3:Trimming a Kernel

# dmesg |grep 'not found'		(看看GENERIC 内核是不是捕捉到了所有 硬件)
# dmesg |grep -i cpu			(蓝色字体 便是阁下的 CPU架构)
CPU: Intel(R) Core(TM) i7 CPU	Q740	@ 1.73GHz (1728.97-MHz K8-class CPU)
<你会不会问我了？  内核配置文件 要写 K8 哦？自然不是！>

判断内核配置 CPU 选项如何填写：
# less /usr/src/sys/amd64/conf/NOTES	(找到你相应架构的目录)
CPU	OPTIONS
cpu			HAMMER		# aka K8, aka Opteron & Athlon64

方法一：根据 GENERIC 调整配置
# vim MYKERNEL

# Basic Options
cpu			HAMMER			(CPU 架构类型)
ident			MYKERNEL		(命名)
makeoptions 	DEBUG=-g		# Build kernel with gdb debug symbols

options 		SCHED_ULE		# ULE scheduler
options		PREEMPTION 		# Enable kernel thread preemption

options		 INET 			# InterNETworking
options		 INET6	 		# IPv6 communications protocols
options		SCTP			# Stream Control Transmission Protocol

options 		FFS 				# Berkeley Fast Filesystem
options 		SOFTUPDATES 	# Enable FFS soft updates support
options 		UFS_ACL 			# Support for access control lists
options		UFS_DIRHASH 		# Improve performance on big directories
options		UFS_GJOURNAL	# Enable gjournal-based UFS journaling

options 		MD_ROOT 		# MD is a potential root device
options 		NFSCLIENT 		# Network Filesystem Client
options 		NFSSERVER 		# Network Filesystem Server
options		NFSLOCKD		# Network Lock Manager
options		NFS_ROOT		# NFS usable as /, requires NFSCLIENT

options 		MSDOSFS 		# MSDOS filesystem
options 		CD9660 			# ISO 9660 filesystem
options 		PROCFS 			# Process filesystem (requires PSEUDOFS)
options 		PSEUDOFS 		# Pseudo-filesystem framework

options		GEOM_PART_GPT	# GUID Partition Tables
options		GEOM_LABEL		# Provides labelization

options 		COMPAT_43TTY 	  	# BSD 4.3 TTY compat [KEEP THIS!]
options 		COMPAT_FREEBSD32 	# Compatible with i386 binaries
options 		COMPAT_FREEBSD4	# Compatible with FreeBSD4
options 		COMPAT_FREEBSD5 	# Compatible with FreeBSD5
options 		COMPAT_FREEBSD6 	# Compatible with FreeBSD6
options 		COMPAT_FREEBSD7 	# Compatible with FreeBSD7

options 	SCSI_DELAY=5000		# Delay (in ms) before probing SCSI
options 	KTRACE				# ktrace(1) support
options 	SYSVSHM			# SYSV-style shared memory
options 	SYSVMSG			# SYSV-style message queues
options 	SYSVSEM			# SYSV-style semaphores

options 	P1003_1B_SEMAPHORES		# POSIX-style semaphores
options 	_KPOSIX_PRIORITY_SCHEDULING 	# POSIX P1003_1B real-time extensions
options 	KBD_INSTALL_CDEV	# install a CDEV entry in /dev
options 	AUDIT				# Security event auditing

# Make an SMP-capable kernel by default
options 	SMP			# Symmetric MultiProcessor Kernel
...	...		...
...	...		...

# Device Drivers
# Floppy drives
# device fdc			(注释掉 没有的设备)
:wq

方法二：Include GENERIC
# vim MYKERNEL
ident	MYKERNEL			(命名)
include	GENERIC			(包含 GENERIC)
options	CPU_SOEKRIS		(添加 选项)

nooption	MSDOSFS	  (撤销 选项)
nodevice	fdc			  (撤销 设备)
:wq

4:Building a Kernel

# cd /usr/src
# make buildkernel KERNCONF=MYKERNEL	()
# make installkernel KERNCONF=MYKERNEL
关于用不用 -j选项：
(-j：理论上核心数 +1更多不起作用，因为 线程与核心 本身无法等同
但是：
由于less /usr/src/UPDATING 文档内提到
General Notes
-------------
Avoid using make -j when upgrading. From time to time in the
past there have been problems using -j with buildworld and/or
installworld. This is especially true when upgrading between
"distant" versions (eg one that cross a major release boundary
or several minor releases, or when several months have passed
on the -current branch).
因此：我建议大家还是不要用了，除了kernel 和 buildworld 其他软件想用无妨！)

5:Testing Kernel

方法一：安装后直接运行 new kernel

方法二：nextboot
# make KERNCONF=MYKERNEL INSTKERNAME=test kernel	(编译安装时起个名字)
此时你已经安装完 new kernel ！

# mv /boot/kernel /boot/kernel.test
# mkdir /boot/kernel
# cp /boot/kernel.good/* /boot/kernel/			(将老版本Kernel 拉回来)

# nextboot -t kernel.test				(下次启动运行kernel.test,仅一次)
# mv /boot/kernel /boot/kernel.previous			(测试后保存 老版本 kernel)
# mv /boot/kernel.test /boot/kernel			(将kernel.test 改为默认 kernel)
------------------------------------------------------------------------------------------------------
声明：这是从书上看到的 我感觉很变态

下面这是 less /usr/src/UPDATING 文档里的方法	(这个很正常)
To test a kernel once
---------------------
If you just want to boot a kernel once (because you are not sure
if it works, or if you want to boot a known bad kernel to provide
debugging information) run
make installkernel KERNCONF=YOUR_KERNEL_HERE KODIR=/boot/testkernel
nextboot -k testkernel

方法三：Loader Prompt
ok unload						(erase the loaded kernel and all modules from memory)

6: