dd: /dev/xillybus_sink: No space left on device

Questions and discussions about the Xillybus IP core and drivers

dd: /dev/xillybus_sink: No space left on device

Postby bnsblue »

Hi,

When I tried to follow the dd example on the bandwidth guideline page (http://xillybus.com/doc/bandwidth-guidelines), I got the following errors.
Code: Select all
$ dd if=/dev/zero of=/dev/xillybus_sink bs=128k
dd: failed to open ‘/dev/xillybus_sink’: Permission denied
$ sudo dd if=/dev/zero of=/dev/xillybus_sink bs=128k
[sudo] password for <my account>:
dd: error writing ‘/dev/xillybus_sink’: No space left on device
63626+0 records in
63625+0 records out
8339537920 bytes (8.3 GB) copied, 1.44206 s, 5.8 GB/s

$ dd if=/dev/xillybus_source of=/dev/null bs=128k
dd: failed to open ‘/dev/xillybus_source’: No such file or directory


My questions are as follows:
(1) Are the outputs normal? Did I really successfully write things into xillybus_sink? It seems that I did successfully write to it with a 5.8GB/s bandwidth, but why is it complaining "dd: error writing /dev/xillybus_sink: No space left on device"?
(2) I've already added the udev rule for xillybus, which changes the permission of xillybus subsystem to 666, but why did I still need to use sudo access to write to xillybus_sink?
(3) The guideline page instructed to use /dev/xillybus_source to test the bandwidth of the other direction. But on my computer I couldn't find the device /dev/xillybus_source as instructed in the same guideline page. Is it normal?

Any hint or suggestion is much appreciated!
bnsblue
 
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Re: dd: /dev/xillybus_sink: No space left on device

Postby support »

Hello,

When things work properly, Xillybus' driver generates device files as /dev/xillybus_{something}. These files don't store anything, but are a means for communication with the hardware.

In your case, it seems like the device files weren't created. And indeed, you weren't allowed to create a file under /dev/ as non-root. Once you gained root privileges, you wrote the data into the disk until it got full. Judging by the impressive rate (5.8 GB/s), all data went to the disk cache in RAM. I suppose you saw some disk activity soon after this.

Same explanation for /dev/xillybus_source.

Why the device files were absent is a question in itself. If the FPGA was loaded properly before the computer's powerup, check if the PCIe device was detected with lspci. Also take a look on the logs (e.g. with dmesg).

Regards,
Eli
support
 
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Re: dd: /dev/xillybus_sink: No space left on device

Postby bnsblue »

Hi Eli,

Thank you for the reply. I forgot to mention that, while the "dd" experiment with xillybus_sink didn't work as expected, experiments with other devices xillybus_read_8 and xillybus_write_8 devices did worked as instructed in the document http://xillybus.com/downloads/doc/xilly ... _linux.pdf (both the basic cat experiment and the more advanced hexdump/memwrite experiments worked as shown in the document.)

Do you know why this (xillybus_sink doesn't work while xillybus_read_8 & xillybus_write_8 work) could happen? Is there any way to troubleshoot?

Thank you!
bnsblue
 
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Re: dd: /dev/xillybus_sink: No space left on device

Postby bnsblue »

Also forgot to mention that I am using the Rev XL for Arria 10 with the dedicated bundle. Not sure if this is relevant. Thank you :)
bnsblue
 
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Re: dd: /dev/xillybus_sink: No space left on device

Postby support »

Hello,

It seems like you missed the little comment saying "replace the /dev/xillybus_* names as required" on the page. The names of the device files should be of those that actually exist. The names "source" and "sink" were used on the web page to clarify their purpose. You can, of course, generate a custom IP core that will generate device files with these names, and you can use the existing one (assuming that it's set up for the performance you expect. After all, you're using an XL core).

Regards,
Eli
support
 
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