Re: [PATCH v7 1/3] PCI: AtomicOps: Do not enable requests by RCiEPs

Jason Gunthorpe
2026-03-30T22:26:34Z

On Mon, Mar 30, 2026 at 04:42:53PM -0500, Bjorn Helgaas wrote:
> [+to amdgpu, bnxe_re, mlx5 IB, qedr, mlx5 maintainers]
>
> On Mon, Mar 30, 2026 at 03:09:44PM +0200, Gerd Bayer wrote:
> > Since root complex integrated end points (RCiEPs) attach to a bus that
> > has no bridge device describing the root port, the capability to
> > complete AtomicOps requests cannot be determined with PCIe methods.
> >
> > Change default of pci_enable_atomic_ops_to_root() to not enable
> > AtomicOps requests on RCiEPs.
>
> I know I suggested this because there's nothing explicit that tells us
> whether the RC supports atomic ops from RCiEPs [1]. But I'm concerned
> that GPUs, infiniband HCAs, and NICs that use atomic ops may be
> implemented as RCiEPs and would be broken by this.

AFAIK none of the NICs are integrated into root complexes in their
topology model..

Jason