On Thu, 21 Jan 2021 15:54:22 +0100 Niklas Schnelle <schne...@linux.ibm.com> wrote:
> On 1/21/21 3:46 PM, Pierre Morel wrote: > > > > > > On 1/21/21 2:37 PM, Niklas Schnelle wrote: > >> > >> > >> On 1/21/21 1:30 PM, Pierre Morel wrote: > > > >>>> > >>>> Just wanted to say that we've had a very similar discussion with > >>>> Cornelia end of last year and came to the conclusion that explicitly > >>>> matching the PFT is likely the safest bet: > >>>> https://lkml.org/lkml/2020/12/22/479 > >>> > >>> What I see there is a discussion on the relation between relaxed access > >>> and MIO without explaining to Connie that we have in the kernel the > >>> possibility to know if a device support MIO or not independently of it > >>> supports the relaxed access. > >>> > >>> The all point here is about taking decisions for the right reasons. > >>> > >>> We have the possibility to take the decision based on functionalities and > >>> not on a specific PCI function. > >> > >> Yes but that goes both ways the functionality of the region has to match > >> that of the device and at least in it's current state the regions > >> functionality > >> matches only ISM in a way that is so specific that it is very unlikely to > >> match anything > >> else. For example it can't support a PCI device that requires non-MIO but > >> also MSI-X. In its current form it doesn't even support PCI Store only PCI > >> Store > >> Block, we had that in an earlier version and it's trivial but then we get > >> the MSI-X > >> problem. > > > > > > What does that change if we take one or the other solution considering the > > checking of MIO/MSIX/relax versus PFT? > > > If it's !MIO && !MSIX && relax_align I'm fine with that check but > then we should also add PCISTG to the region. > Just to double check: that would today cover only ISM (which doesn't use PCISTG), correct? /me getting a bit lost in this discussion :)
