Re: [Qemu-devel] [PATCH] hw/pci/pci-stub: Add msi_enabled() and msi_notify() to the pci stubs

[Paolo Bonzini <pbonzini@redhat.com>]

On 19/02/19 17:07, Thomas Huth wrote:
> Some machines have an AHCI adapter, but no PCI. To be able to
> compile hw/ide/ahci.c without CONFIG_PCI, we still need the two
> functions msi_enabled() and msi_notify() for linking.
> This is required for the upcoming Kconfig-like build system, if
> a user wants to compile a QEMU binary with just one machine that
> has AHCI, but no PCI, like the ARM "cubieboard" for example.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  hw/pci/pci-stub.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/hw/pci/pci-stub.c b/hw/pci/pci-stub.c
> index b941a0e..c04a5df 100644
> --- a/hw/pci/pci-stub.c
> +++ b/hw/pci/pci-stub.c
> @@ -53,3 +53,14 @@ uint16_t pci_requester_id(PCIDevice *dev)
>      g_assert(false);
>      return 0;
>  }
> +
> +/* Required by ahci.c */
> +bool msi_enabled(const PCIDevice *dev)
> +{
> +    return false;
> +}
> +
> +void msi_notify(PCIDevice *dev, unsigned int vector)
> +{
> +    g_assert_not_reached();
> +}
> 

Makes sense, but it is also abstraction time. :)  What if instead there
was a function

void msi_allocate_irqs(PCIDevice *pdev, int num, bool fallback_to_intx);

and then ich.c did

    irqs = msi_allocate_irqs(pdev, 1, true);
    s->irq = irqs[0];
    g_free(irqs);

?  "if msi_enabled raise MSI else raise INTX" is really a common idiom.

Thanks,

Paolo