How kernel communicates with outside when it's started?

Forum: The Linux Kernel Hackers' Guide
Keywords: kernel,file system,
Date: Mon, 16 Feb 1998 23:03:17 GMT
From: Xuan Cao <cao@cobalt.chem.uidaho.edu>

I am writing some kernel modules that is supposed to executed after the init process has been started. The purpose of these modules is to write some kernel data out to a normal file. But I don't know what kinds of functions are available for those modules. Some functions such as open(), read(), write() which worked before init process don't work in those kernel modules after init process is started. I guess the main problem might be the kernel don't have control over the system after init process is started. But how can I get some of the data out of kernel to a file by using the kernel modules? The problem is can or how I use some functions (file operations, IPC, etc) in a kernel module which is only executed after the system has started and is running normally. Thanks in advance!