Re: [Qemu-ppc] [PATCH] openpic: Initialize destmask at reset

Re: [Qemu-ppc] [PATCH] openpic: Initialize destmask at reset

[Alexander Graf]

On 21.05.14 21:47, Alexander Graf wrote:
>
>> Am 21.05.2014 um 18:33 schrieb Paul Janzen <pcj@pauljanzen.org>:
>>
>>> On Wed, May 21, 2014 at 12:45 AM, Alexander Graf <agraf@suse.de> wrote:
>>>
>>> Or maybe it's safer overall to just call write_IRQreg_idr() instead of
>>> setting idr directly? That would update destmask along the way as well and
>>> we would catch all subtle corner cases.
>> I considered this initially but decided to go with the simpler
>> approach.  But you have convinced me. Specifically, the current
>> implementation does not reset src->output or src->nomask, which
>> write_IRQreg_idr() will. I will test this change and re-submit the
>> patch.
>>
>>> Do you have a simple test case for this patch? We seem to have the same bug
>>> in the in-kernel KVM MPIC emulation code and I'd like to have it fixed there
>>> as well, but I don't really like to do that change blindly.
>> I have tested this patch using a proprietary embedded operating system
>> which doesn't bother to initialize the IDR registers.
> Do you think it'd be possible for you to test whether it works with kvm when I give you a patch? Do you have real hardware to run kvm on? :)

I just checked - we don't properly implement reset at all in the 
in-kernel MPIC we do in KVM. So it's merely something to keep in mind 
for now until someone sits down and implements proper reset support ;).


Alex

Re: [Qemu-devel] [Qemu-ppc] [PATCH] openpic: Initialize destmask at reset

[Alexander Graf]

On 21.05.14 21:47, Alexander Graf wrote:
>
>> Am 21.05.2014 um 18:33 schrieb Paul Janzen <pcj@pauljanzen.org>:
>>
>>> On Wed, May 21, 2014 at 12:45 AM, Alexander Graf <agraf@suse.de> wrote:
>>>
>>> Or maybe it's safer overall to just call write_IRQreg_idr() instead of
>>> setting idr directly? That would update destmask along the way as well and
>>> we would catch all subtle corner cases.
>> I considered this initially but decided to go with the simpler
>> approach.  But you have convinced me. Specifically, the current
>> implementation does not reset src->output or src->nomask, which
>> write_IRQreg_idr() will. I will test this change and re-submit the
>> patch.
>>
>>> Do you have a simple test case for this patch? We seem to have the same bug
>>> in the in-kernel KVM MPIC emulation code and I'd like to have it fixed there
>>> as well, but I don't really like to do that change blindly.
>> I have tested this patch using a proprietary embedded operating system
>> which doesn't bother to initialize the IDR registers.
> Do you think it'd be possible for you to test whether it works with kvm when I give you a patch? Do you have real hardware to run kvm on? :)

I just checked - we don't properly implement reset at all in the 
in-kernel MPIC we do in KVM. So it's merely something to keep in mind 
for now until someone sits down and implements proper reset support ;).


Alex