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Gizmotoy's avatar
Gizmotoy
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7 years ago

Intel AN829 PCIe DMA example failing to create /proc/devices entry

I'm working on bringing up AN829, the Altera DMA example, on a Cyclone 10 GX Development Kit. The FPGA is loaded and shows up on the PCIe bus.

05:00.0 Non-VGA unclassified device: Altera Corporation Device e003 (rev 01)

And the kernel module is loaded

Cyclone10GX_PCIeGen2x4_DMA_18_0_project/driver/AN829_driver$ lsmod | grep altera
altera_dma             20480  0
altera_cvp             16384  0
fpga_mgr               16384  1 altera_cvp

But the device isn't listed in /proc/devices

Cyclone10GX_PCIeGen2x4_DMA_18_0_project/driver/AN829_driver$ cat /proc/devices
Character devices:
  1 mem
  4 /dev/vc/0
  4 tty
  4 ttyS
  5 /dev/tty
  5 /dev/console
  5 /dev/ptmx
  5 ttyprintk
  6 lp
  7 vcs
 10 misc
 13 input
 21 sg
 29 fb
 89 i2c
 99 ppdev
108 ppp
116 alsa
128 ptm
136 pts
180 usb
189 usb_device
204 ttyMAX
216 rfcomm
226 drm
240 mei
241 hidraw
242 aux
243 ptp
244 pps
245 ttyDBC
246 bsg
247 hmm_device
248 watchdog
249 rtc
250 dax
251 dimmctl
252 ndctl
253 tpm
254 gpiochip
 
Block devices:
  7 loop
  8 sd
  9 md
 11 sr
 65 sd
 66 sd
 67 sd
 68 sd
 69 sd
 70 sd
 71 sd
128 sd
129 sd
130 sd
131 sd
132 sd
133 sd
134 sd
135 sd
253 device-mapper
254 mdp
259 blkext

Since the device isn't listed in /proc/devices, it can't get the major/minor identifiers required to create /dev/altera_dma, and the altera_load_dma process fails.

Any idea why the kernel module might load, but fail to create an entry in /proc/devices?

The OS is Ubuntu 16.04

Thanks!

7 Replies

  • Gizmotoy's avatar
    Gizmotoy
    Icon for New Contributor rankNew Contributor
    7 years ago

    Yes, "sudo ./install cyclone10" is what creates and load the "altera_dma" module you see in the lsmod output. However, this fails with an obscure error around the following lines:

    major=`grep -w $module /proc/devices | cut -f1 -d" "`
mknod /dev/$device c $major 0

    Since the card isn't listed in /proc/devices, $major is null and mknod fails. I cannot execute "sudo ./run" successfully since the driver did not fully load.

    I was able to get a little farther, though. It turns out AN829, within the Quartus PCIe Hard IP Core settings, uses a PCIe device class of 0x000000. This is technically invalid. I changed it to 0x040000 and now the driver installs. This is great news.

    Unfortunately, the card tries to reserve a large block of address space (0x000000 - 0x7FFFFF for BAR 2 and 0x800000 - 0x8001FF for BAR 0). The machine I have it slotted in seems to be failing to allocate that address space (it's over half of the total available PCIe space).

    So I made progress, but still haven't gotten AN829 working.

  • SengKok_L_Intel's avatar
    SengKok_L_Intel
    Icon for Regular Contributor rankRegular Contributor
    7 years ago

    This design was validated in our Linux system without problem. You may check the Kernel in use by using the lspci -v.

    Regards -SK ​

  • WCarb1's avatar
    WCarb1
    Icon for New Contributor rankNew Contributor
    6 years ago

    Hi,

    Were you able to solve this issue? I have been trying to reduce the required memory allocation of BAR2 to less than 512MB (working with embedded devices ) in the reference design with no results. The Cyclone 10 GX Development Kit appears with lspci -vv but memory shows as <unassigned> for each block.

    • Gizmotoy's avatar
      Gizmotoy
      Icon for New Contributor rankNew Contributor
      6 years ago

      I was able to get it working, but it was by switching to a machine with a larger PCIe address space. I kept getting <unassigned> for the memory space when I was on the other computer. It's not a great solution, but it worked.

      • WCarb1's avatar
        WCarb1
        Icon for New Contributor rankNew Contributor
        6 years ago

        Yes, in machines with larger PCI address memory space I had no problems. In fact, the issue was in one particular embedded device with limited memory space. However, I managed to solve it modifying the IP core from system designer to have a smaller PCIe memory size and changing the base addresses. Also the driver kernel from the linux side required some tuning for these new memory chunks. Thank you for all your help!

  • SengKok_L_Intel's avatar
    SengKok_L_Intel
    Icon for Regular Contributor rankRegular Contributor
    6 years ago

    Just FYI.. I recently tested AN829 in centos for Arria 10 device, everything is working fine. Perhaps, you can check if the same problem happen in other Linux OS and see if there is any dependency. ​