Re: [PATCH v3 2/4] net: qrtr: Assign unique node id for MHI endpoints

[Marcel Holtmann <marcel@holtmann.org>]

Hi Juha-Matti,

>>> Well, in defense of Manivannan's patchset it currently works for PCI+AHB
>>> setups better than the last version of that by Denis/Mihai/me (although 
>>> I could easily fix that), and it may be simpler for userspace to
>>> continue using nid than having to bind to an endpoint, which requires
>>> more changes in userspace code.
>>> 
>>> The userspace just needs to know the nid.
>> 
>> and existing userspace? You can _NOT_ break existing userspace.
>> 
>> Don’t you need to re-write all existing QRTRIPC packets to actually even make this work?
> 
> Well, from what I understand this rewriting is the plan.
> 
> It is true that if someone has a single card, the nid changes, thus
> maybe breaking userspace if the userspace has hardcoded nid.
> 
> But if someone has multiple cards, the breakage to userspace is less
> with this patch, since userspace can keep on using the same code and
> just change the nid, whereas with the endpoint_id patch, the userspace
> needs code changes to bind to an endpoint.

the general rule for Linux is to _not_ break existing userspace.

Regards

Marcel