还需要嘛？

风继续吹

我刚看了精华区的帖子，但是我看过的书上说还要先删除linux的连接，然后再建立新内核和linux的连接，这样可以避免覆盖掉原来的文件，精华区的帖子没有这些步骤了，是简化了？还是真的不需要了？

Dragonfly

u had better do this.
before 2.4.18 i think, they are uncompress to linux, so remove that symbol link can avoid to overwrite u existed kernel.
after 2.4.18, they uncompress to linux-2.x.x. so will not overwrite existed one. but update the linux symbol link to the kernel dir u wnat to use is a good choice.

jjww

问一句，在make menuconfig的时候，产生的config文件存在何处？
我只是通过另存才看见我config的内容, 和FreeBSD完全不一样，还没适应过来。

另外，我想问一句，linux下通过内核模块编程加入内核空间和直接在make的时候ld在内核里，有什么区别吗？

前两天看了一下系统启动的平台无关性部分，感觉linux的模块化不是很明白，假设我要加一个内核子系统在内核里，该子系统需要在VFS之间加载，难道，我还必须改启动的部分吗？内核能不能动态识别，排序我加载的子系统。

顺便就在这里问dragonfly了，回去看书了，呜呜，今晚又没看考试的书，怎么过呀？！   

Dragonfly

yes, freebsd is different with linux. i compiled bsd before in order to use dummynet and include some of my nic driver.
ls -a, it is a .config file.
module is loaded when need, but kernel is always there. save u some kernel space. load time...
yes, u are right, the order in kernel is fixed, u can not adjust the order, at least as far as i know. i think the assumption in kernel is that it load key part in a fixed order, and other parts can be reordered, like the order in init.d and rc.sysinit

Dragonfly

btw, i can discuss with dr jin about u test. hehe

jjww

thx!

也就是说，如果我编写一个子系统，很特殊，必须在VFS加载前完成，难道还需要我在vfs_caches_init()函数前加上该子系统的初始化调用吗？ 如果这样，我觉得linux在模块化的灵活控制方面比FreeBSD差了一些，在FreeBSD看来，无论是内核模块还是内核本身都是一样的，好比我打算写一个driver，在确定之前，一般用module形式，FreeBSD可以在开机的时候通过rc.conf设置动态加载，然后在平台无关性部分，根据该driver提供的子系统号等信息，采用冒泡法排序，因此，只要我在模块里指定它的加载等级SI_SUB_xxx就可以了。当然，如果需要开发一个完全自己的子系统，也可以在kernel.h里添加自己的子系统编号，不过一般用不到这么复杂。

也就是如果不修改start_kernel，我只能在该函数之后添加自己的模块，对吗？
你能谈谈linux对模块的认识和组织吗？

thx again

Dragonfly

yes, if that is needed before bfs, u have to modify the start_kernel(). but think again if u really need load that part before vfs init. so u can see that start_kernel() only contain a small set of init. most of them can be init later or on demand.
i think for freebsd, there must be an order as well. for example, u can not load vfs before vm sub system, u can not init pci beofre u init interrupt table and trap. so some orders are already fixed.
most of the driver modules can by dynamically loaded by using config file in linux.

i think ldd 2nd chapter 2 and chpater 11, qjfx chapter 8, already are too good to be true. so i have nothing to say here.    but if sb have problem, he will ask here and i will answer.