Hi All, I am using Linux on a Compact PCI system with a System Controller and a set of Peripheral boards. Each time one of these peripheral boards is hot swapped a NMI interrupt is generated on the System Controller board. I have in mind to write a driver that handles these NMI interrupts. I don't really want to start hacking the kernel source, but would rather like to build a module that can be loaded at some point. My idea is to get the module to replace the NMI vector to the existing NMI handler function (in linux/arch/i386/kernel/entry.S that is set from the trap_init function in /linux/arch/i386/kernel/traps.c) with my own handler function, calling the previous handler if necessary after my handler has done its bit. A pretty standard idea. Now, in terms of swimming, I still have my inflatable armbands on here! So I was wondering if this were possible? I guess that I would need to first save the existing content of the NMI IDT entry, the entry point to the existing NMI handler, then modify the NMI IDT entry with the pointer to my NMI handler. I am still guessing, but would the saved entry point be an address relative to a particular memory page? And would the new entry saved there also be seen as relative to the same page? i.e. not only would I not be able to call the previous NMI handler from my module, but my own NMI handler would not get called either, and the system would crash? Also would I be allowed to modify the NMI IDT entry from my module? Looking through the traps.c file I see that there is a function trap_init_f00f_bug which makes the IDT read only? As I said above, my armbands are fully inflated here, so I hope some this makes sense, and any help or pointers you could give me would be warmly welcomed, Many thanks for you time, Best wishes, Simon. -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
