Re: [PATCH] hw/ide: Remove status register read side effect

[Mark Cave-Ayland]

On 04/03/2020 03:11, address@hidden wrote:

>> cmd646_update_irq() only seems to raise PCI interrupt, should it also
>> have 
>> an option to use INT 14 and 15 in legacy mode similar to what my
>> patch 
>> does for via-ide?
> 
> Looking through /qemu/hw/ide/cmd646.c it doesn't look like QEMU has
> support for legacy mode. At the very least, it looks like we default to
> PCI native mode:
> 
> static void pci_cmd646_ide_realize(PCIDevice *dev, Error **errp)
>       ...
>       pci_conf[PCI_CLASS_PROG] = 0x8f;
>       ...
> 
> To add support for legacy mode it would require changing
> cmd646_update_irq() and maybe cmd646_set_irq() so that interrupts are
> conditionally raised on IRQ14 and/or IRQ15 when the ports are in legacy
> mode.

Yes, that's correct. However I'm quite confident from booting other non-Solaris 
OSs
under qemu-system-sparc64 that PCI native mode is being used, particularly as 
it is
possible to see the related PCI sabre IRQ routing configuration changes.


ATB,

Mark.