[Qemu-devel] QEMU pci mach-virt: setting PCI_INTERRUPT_LINE?

[Qemu-devel] QEMU pci mach-virt: setting PCI_INTERRUPT_LINE?

[Claudio Fontana]

Hello,

I am trying to set the pci interrupt line field in the configuration space
(offset 0x3c), since it is initialized as zero.

I would like to set it to the right value as read from the device tree,
in order for other existing software which relies on it to be able to work unmodified..

but it does not seem to work (I seem to read back zero even after setting the PCI_INTERRUPT_LINE field).

I am also reading the interrupt pin, but that one instead seems to work out of the box..

Thank you for any suggestion,

Claudio

Re: [Qemu-devel] QEMU pci mach-virt: setting PCI_INTERRUPT_LINE?

[Claudio Fontana]

On 24.02.2015 15:34, Claudio Fontana wrote:
> Hello,
> 
> I am trying to set the pci interrupt line field in the configuration space
> (offset 0x3c), since it is initialized as zero.
> 
> I would like to set it to the right value as read from the device tree,
> in order for other existing software which relies on it to be able to work unmodified..
> 
> but it does not seem to work (I seem to read back zero even after setting the PCI_INTERRUPT_LINE field).
> 
> I am also reading the interrupt pin, but that one instead seems to work out of the box..
> 
> Thank you for any suggestion,
> 
> Claudio

By the way, I am currently just avoiding to rely on PCI_INTERRUPT_LINE for AArch64,
but shouldn't the register be programmable?

Ciao,

Claudio

Re: [Qemu-devel] QEMU pci mach-virt: setting PCI_INTERRUPT_LINE?

[Alexander Graf]

On 25.02.15 13:07, Claudio Fontana wrote:
> 
> 
> On 24.02.2015 15:34, Claudio Fontana wrote:
>> Hello,
>>
>> I am trying to set the pci interrupt line field in the configuration space
>> (offset 0x3c), since it is initialized as zero.
>>
>> I would like to set it to the right value as read from the device tree,
>> in order for other existing software which relies on it to be able to work unmodified..
>>
>> but it does not seem to work (I seem to read back zero even after setting the PCI_INTERRUPT_LINE field).
>>
>> I am also reading the interrupt pin, but that one instead seems to work out of the box..
>>
>> Thank you for any suggestion,
>>
>> Claudio
> 
> By the way, I am currently just avoiding to rely on PCI_INTERRUPT_LINE for AArch64,
> but shouldn't the register be programmable?

As far as I understand the register should really just be a scratch r/w
register, yeah. Are you sure you're writing in byte granularity?


Alex

Re: [Qemu-devel] QEMU pci mach-virt: setting PCI_INTERRUPT_LINE?

[Claudio Fontana]

On 25.02.2015 13:08, Alexander Graf wrote:
> 
> 
> On 25.02.15 13:07, Claudio Fontana wrote:
>>
>>
>> On 24.02.2015 15:34, Claudio Fontana wrote:
>>> Hello,
>>>
>>> I am trying to set the pci interrupt line field in the configuration space
>>> (offset 0x3c), since it is initialized as zero.
>>>
>>> I would like to set it to the right value as read from the device tree,
>>> in order for other existing software which relies on it to be able to work unmodified..
>>>
>>> but it does not seem to work (I seem to read back zero even after setting the PCI_INTERRUPT_LINE field).
>>>
>>> I am also reading the interrupt pin, but that one instead seems to work out of the box..
>>>
>>> Thank you for any suggestion,
>>>
>>> Claudio
>>
>> By the way, I am currently just avoiding to rely on PCI_INTERRUPT_LINE for AArch64,
>> but shouldn't the register be programmable?
> 
> As far as I understand the register should really just be a scratch r/w
> register, yeah. Are you sure you're writing in byte granularity?
> 
> 
> Alex

Relatively sure, yeah.. I'll check again, but at least for x86_64 the get function works.
It's OSv's pci-function.cc

u8 function::get_interrupt_line()
{
    return pci_readb(PCI_CFG_INTERRUPT_LINE);
}

void function::set_interrupt_line(u8 irq)
{
    pci_writeb(PCI_CFG_INTERRUPT_LINE, irq);
}

I'll try to debug with PCI_DEBUG and such things, see if I find out something...

Ciao,

Claudio





-- 
Claudio Fontana
Server Virtualization Architect
Huawei Technologies Duesseldorf GmbH
Riesstraße 25 - 80992 München

office: +49 89 158834 4135
mobile: +49 15253060158