Re: Current panic on boot on H11DSI motherboard with epyc cpu (nexus_add_irq: failed)

> On Apr 18, 2018, at 1:42 PM, John Baldwin <jhb_at_freebsd.org> wrote:
>> 
>> Chenged made for it was
>> 
>> Index: sys/x86/x86/nexus.c
>> ===================================================================
>> --- sys/x86/x86/nexus.c (revision 332663)
>> +++ sys/x86/x86/nexus.c (working copy)
>> _at__at_ -698,7 +698,7 _at__at_
>> {
>> 
>>        if (rman_manage_region(&irq_rman, irq, irq) != 0)
>> -               panic("%s: failed", __func__);
>> +               panic("%s: failed irq is: %lu", __func__, irq);
>> }
> 
> Ohhhh, this is a different issue.  Sorry.  As a hack, try changing
> 'FIRST_MSI_INT' to 512 in sys/amd64/include/intr_machdep.h.  The issue
> is that some systems now include more than 256 interrupt pins on I/O
> APICs, so IRQ 256 is already reserved for use by one of those
> interrupt pins.  The real fix is that I need to make FIRST_MSI_INT
> dynamic instead of a constant and just define it as the first free IRQ
> after the I/O APICs have probed.

I'm testing a very large AMD Epyc system, and I had to change FIRST_MSI_INT to 768, but that fixed this issue for me.