Re: [Xen-devel] Re: Continuing problems booting

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Gerd Hoffmann wrote:
> > Hm.  I was not really planning on supporting no-ACPI; I've only hooked
> > acpi_register_gsi, which is called via acpi_pci_irq_enable.  I guess
> > you'd need to do something in pirq_enable_irq as well, and I'm not sure
> > if all the stuff gets set up properly for IO_APIC_get_PCI_irq_vector to
> > work.
> >     
> I have -rc6 kernel which *does* boot.  Maybe that was by accident ;)
>   
Hm, well I don't remember adding any new ENOSYSes in there, so perhaps 
the core kernel has changed in some way under us.
I'm guessing it's this:

static int
__setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
{
        struct irqaction *old, **old_ptr;
        const char *old_name = NULL;
        unsigned long flags;
        int shared = 0;
        int ret;

        if (!desc)
                return -EINVAL;

        if (desc->chip == &no_irq_chip)
                return -ENOSYS;
...


which gets called from request_irq.  So that means that the desc is 
getting allocated but the chip hasn't been set up.  Are you using sparse 
irqs?
> The kernel initializes legacy interrupts anyway.  I think you don't need
> to do more to handle apic-less machines, no?
>   
I guess not, if its only using irqs < 16.  How old is this machine 
anyway; do you really mean its a literal i386?
But the info I'm using to set up the legacy interrupts comes from acpi 
tables, I think, so perhaps its misprogramming the legacy interrupts, 
whereas before they just happened to work in their default config (???).
   J

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