Hello everyone. I am a new beginner to OS developer. when I am developping my OS, I got issues which is ralated to MSI interrupt.
in my os, I disabled legacy PIC and enabled APIC, and I also added HPET timer. all these devices interrupts are working well through APIC. But when I am trying to add MSI , I cannot get it working.
according to chapter 6.8 of <PCI local bus sepecification 2.3> ， I write 0xFEE00000(only 1 cpu used) to message address register, 0 to upper address(this device supports 64bits address). and then write 0x26(I want to use IRQ6) to message data. and then set bit 0 of message control. set Interrupt Disable of PCI cmd register at last. connect ISR to IRQ6. when the trigger happens, no ISR is called.
can you help me how to fix this issue? it would be a great appreciate to you.
how to make PCI MSI working?
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Octocontrabass
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Re: how to make PCI MSI working?
I'm not sure it's safe to assume the BSP APIC ID will always be 0. It probably will be, but you should still check.marcrew wrote:I write 0xFEE00000(only 1 cpu used)
IRQ6 is an input to the legacy PIC and the IOAPIC. There's no such thing as IRQ6 when you're using MSIs.marcrew wrote:0x26(I want to use IRQ6)
What are the values of the other bits in the command register? You need to set the bus master bit to receive MSIs.marcrew wrote:set Interrupt Disable of PCI cmd register
Re: how to make PCI MSI working?
thanks for the reply.
the CMD reg is 0x407, status reg is 0x10. it means bus master is set ,and legacy int is disabled ,right?I have checked the LAPIC ID , it is 0 .Octocontrabass wrote:I'm not sure it's safe to assume the BSP APIC ID will always be 0. It probably will be, but you should still check.marcrew wrote:I write 0xFEE00000(only 1 cpu used)
OK, I connected vector 0x26(which is IRQ6 to PIC) to handler, then I wrote 0x26 to message data. is it the correct way?IRQ6 is an input to the legacy PIC and the IOAPIC. There's no such thing as IRQ6 when you're using MSIs.marcrew wrote:0x26(I want to use IRQ6)
What are the values of the other bits in the command register? You need to set the bus master bit to receive MSIs.marcrew wrote:set Interrupt Disable of PCI cmd register
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Octocontrabass
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Re: how to make PCI MSI working?
That's the correct value, but I still don't understand where you're getting IRQ6.marcrew wrote:OK, I connected vector 0x26(which is IRQ6 to PIC) to handler, then I wrote 0x26 to message data. is it the correct way?
Right.marcrew wrote:the CMD reg is 0x407, status reg is 0x10. it means bus master is set ,and legacy int is disabled ,right?