eideticom / p2pmem-pci Goto Github PK

Add this and/or others like it to the merge flow to assist in code quality going forward.

OS: Ubuntu 18.04.4 LTS
Kernel: 4.20.0

I am currently testing a custom device driver with p2pmem-pci userspace driver. My goal is to write a data to device's MMIO register through p2pmem-pci device.

#define _GNU_SOURCE 1
...
int fd = open("/dev/p2pmem0", O_WRONLY | O_DIRECT);

The open() returns -EINVAL due to O_DIRECT flag. If I remove O_DIRECT, open() succeeds but write operations do not work as intended (no MMIO write).
Manual of open() says the filesystem should not have journaling, which requires write buffer, so I also run the program in the journal-disabled ext4 fs, but have no lock.

Could you please let me know what should I do to make O_DIRECT works?

Hi,

I have two NVMe device with CMB.
When I want to use pread() form /dev/nvme0n1 to /dev/p2pmem0, it will stuck.
I trace the code and found it is fail in kernel function pci_p2pdma_map_sg_attrs().
It always report p2pdma map type unknown (PCI_P2PDMA_MAP_UNKNOWN).
Could you help me or give me some comment to fix this issue ?

Thank,
Joshua Lin

OS: Ubuntu 18.04.4 LTS
Kernel: 5.14.10
(re-build kernel and enable CONFIG_PCI_P2PDMA)

When we install p2pmem-pci.ko into a kernel there is a chance it will load before the device driver(s) for the PCIe devices that are publishing p2pdma memory (nvme for example). Therefore we want this module to load as late as possible via a late_initcall().

Hi,
I have no NVMe with CMB, but I have an FPGA that can be configured with a BAR mapped to its internal LPDDR. I tried this repo and exposed the BAR to user space as /dev/p2pmem0. But when I ran the p2pmem-test application, like "./p2pmem-test /dev/nvme0n1 /dev/nvme1n1 /dev/p2pmem0 -c 1 -s 4k --check" .
It ends up with a pwrite I/O error.
From the dmesg I can see the "blk_update_request: I/O error, dev nvme0n1, sector 0 op 0x1:(WRITE) flags 0x8800 phys_seg 1 prio class 0" error message.
So I am curious if we still have the bounce buffer support in p2pmem. Thanks in advance!