On 2020/1/17 3:51, Jason Gunthorpe wrote: >>> What happens to your userspace if it runs on an old kernel and tries >>> to use extended atomic? >>> >>> Jason >>> >> Hi Jason, >> >> If the hns userspace runs with old kernel, the hardware will report a asynchronous >> event for the extended atomic operation and modify the qp to error state because >> the enable bit in this qp's context hasn't been set. >> >> The driver will print like this: >> >> [ 1252.240921] hns3 0000:7d:00.0: Invalid request local work queue 0x9 error. >> [ 1252.247772] hns3 0000:7d:00.0: no hr_qp can be found! > Ideally the provider will not set > IBV_PCI_ATOMIC_OPERATION_4_BYTE_SIZE_SUP and related without kernel > support.. > > I've applied this patch, but I feel like you may need a followup to > fix the capability reporting? > > Jason Hi Jason, Thank for your suggestions. But I'm confuse about the relationship between "PCI ATOMIC" in this macro and atomic operations in RDMA. I found the related series on patchwork: https://patchwork.kernel.org/cover/10782873/ And I found the description about atomic operations in PCIe specification v4.0: "An Atomic Operation (AtomicOp) is a single PCI Express transaction that targets a location in Memory Space, reads the location’s value, potentially writes a new value back to the location, and returns the original value. This "read-modify-write" sequence to the location is performed atomically." It seems that the atomic for PCIe and RDMA is different concepts, and the macro IBV_PCI_ATOMIC_OPERATION_4_BYTE_SIZE_SUP is for PCIe atomic. Could you please give me more suggestions about them? Thanks Weihang
