I'm in the process of developing an embedded system based off RH 7.2. I'm using 2.4.18 with preempt, lockbreak, and some other tweaks. This system will occasionally need to run some code that does some "strange" things to the system hardware (having to do with security considerations). This action, if done while the system is running would more than likely cause a kernel crash. This system is headless, so dual-booting into DOS isn't really an option. My idea is to have this code run in kernel space after the kernel has shut down, and all things are quiescent. What I'm searching for are hooks by which I can cause code to be run after the kernel is shut down. The kernel seems to provide a mechanism for doing this via the register_reboot_notifier() call, which arranges to call code blocks when sys_reboot() is called. My current plan is that I could make this code the notifier block of a module, and I would install this module just before halting the system (when doing the "strange" things is necessary). The module's code would then (hopefully) execute lastly, at the least dangerous time. Questions: Are there any pointers, URLs, etc., that explain how the kernel shuts itself down? I've walked through the sys_reboot() code, and I'm wondering if I've missed anything. Are there any pointers, URLs, etc., that explain what the register_reboot_notifier() call is for, how it should be used, semantics, etc. I think I understand it, but more info would be good. Does anyone have a feel as to whether I'm taking the right approach? Is there a better way to be thinking about this problem? Assuming that the register_reboot_notifier() method is acceptable, is there a way to guarantee that my code block will be the last thing that is run? Has anyone tried anything like this before? If so, I'd like to pick your brain. :-) Thanks in advance, stuart. -- Stuart McDow +1-512-345-5006, ext. 15 Ticom Geomatics, Inc. fax: +1-512-345-9992 9130 Jollyville Rd., STE 300 smcdow@ticom-geo.com Austin, TX 78759 USA -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
