Re: [PATCH v9 4/7] hw/isa/vt82c686: Implement PCI IRQ routing

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Hi Zoltan,

On 7/3/23 12:42, BALATON Zoltan wrote:
> The real VIA south bridges implement a PCI IRQ router which is configured
> by the BIOS or the OS. In order to respect these configurations, QEMU
> needs to implement it as well. The real chip may allow routing IRQs from
> internal functions independently of PCI interrupts but since guests
> usually configute it to a single shared interrupt we don't model that
> here for simplicity.
> 
> Note: The implementation was taken from piix4_set_irq() in hw/isa/piix4.
> 
> Suggested-by: Bernhard Beschow <shentey@gmail.com>
> Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
> Reviewed-by: Bernhard Beschow <shentey@gmail.com>
> Tested-by: Rene Engel <ReneEngel80@emailn.de>
> ---
>   hw/isa/vt82c686.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 42 insertions(+)


> +static int via_isa_get_pci_irq(const ViaISAState *s, int irq_num)
> +{
> +    switch (irq_num) {
> +    case 0:
> +        return s->dev.config[0x55] >> 4;
> +    case 1:
> +        return s->dev.config[0x56] & 0xf;
> +    case 2:
> +        return s->dev.config[0x56] >> 4;
> +    case 3:
> +        return s->dev.config[0x57] >> 4;

Shouldn't this be & 0xf?

(This is why I prefer extract8() over manual bits extraction)

> +    }
> +    return 0;
> +}