Re: [Qemu-arm] [Qemu-devel] [PATCH v2 1/2] Increased the size of requester_id field from MemTxAttrs

[Diana Madalina Craciun]

Hi Eric,

On 07/26/2017 03:23 PM, Auger Eric wrote:
> Hi Diana,
> On 23/05/2017 13:12, Diana Craciun wrote:
>> The PCI requester ID field is 16 bits. The requester_id field
>> from MemTxAttrs is used for MSIs to specify the device ID for
>> the platforms where this device ID is needed (e.g virt machine + GICv3
>> ITS). However, if more entities that uses MSIs in the system are used,
>> 16 bit is no longer enough to represent the device ID. Increased the size
>> of this field to 24 bits in order to accomodate 256 entities.
>> Also the name requester_id does no longer reflect the content, so
>> the name was changed to stream_id.
> I think both deviceid and streamid can be up to 32 bits in theory.

Yes, both of them can be up to 32 bit. I can extend the field to 32 bit.

>
> With respect to the renaming, stream_id really is ARM specific and
> corresponds to the ID space before the SMMU while you mostly address
> device id problematics here (ie. space id input to the interrupt
> controller). Maybe a more generic terminology such as originator id
> could be used or source id (I think this is Intel terminology though).

I agree, originator id sounds good and so far it doesn't seem to overlap
to other specific terminology.

>
> Maybe the changes in semantics of the field should be
> associated/combined with its new computation found in next patch? see
> comments in subsequent patch.

I agree.

Thanks,

Diana