Hello list, My query has to do with Intel Hardware and MSI (rather than its implementation in Linux) but trying my luck to see if anyone has any suggestions here. I have an OS independent qury on the MSI using Intel-APIC (945 chipset). I'm trying to make MSI work on a custom OS, and I'm working on the system "bus driver" level rather than at the device driver level. I understand that to generate MSI, the device function will generate PCI write transaction to write the contents of its MDR into address specified in MAR. This is currently not generating the MSI for my device. To blame the device as faulty or to keep Intel processor out of suspicion, I want to prove that writing the contents of MDR into the address specified by MAR ACTUALLY will generate an interrupt to the processor. Is there a way I can prove that by a demonstration in SW? I wrote a small piece of code that does what the device HW is supposed to do. It writes the "a value" into "an address" and expects to generate an interrupt to processor as a result. Please note that this "value" and "address" are calculated in accordance with sec 9.12 (MSI) of ""Intel(r) 64 and IA-32 Architectures Software Developer's Manual" (http://www.intel.com/Assets/PDF/manual/253668.pdf) Also note that this "value" and "address" is really what will be programmed into MDR and MAR respectively on the device. But the end result is that when my demo code does exactly what the PCI device is supposed to do, it gets an APIC error interrupt with local APIC error status register = 0x80, which implies that the processor is trying to access a register in the processor's local APIC register address space that is reserved. Looking into the same above document sec 9.6.3, quite right, because the "address" that is to be programmed in MAR is actually reserved. So does that mean that the PCI device can write to it, but my SW (running on processor) cannot write to it? I'd really appreciate if you could please give me some pointers in this regard. Thanks & best Regards, Rajat Jain -- To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs
