can only read 0 after 536869888 points

[Guest]

Hi Eli,

Now I am trying to write a big file to FPGA for parallel filtering and signal detection. However, after 536869888*32 bits data loopback transmission, every value read after 536869888 data point is always 0(which should not be). I don't know why this 536869888 is a constant length of data that Xillybus can loopback.

I've tried several IP version but it seems still be the same. This issue has been there for a week that I still have no clue what is possibly wrong.

Would appreciate it if you could give any clue.

Best,
Chongxi

[Guest]

I just realize that it is 1.999GB, almost 2GB. So that might give a bit clue. Again this could be a software `read()` problem? After 2GB reading everything read out can only be zero because of 2GB limit at some place?

Best,
Chongxi

[support]

Hello,

This is definitely not a Xillybus issue. If you have the original loopback logic in the FPGA, check your own test program please.

You didn't mention if you're working with Linux or Windows. In some cases, Windows can have trouble reading files beyond 2 GB.

Do you verify that your read() and write() operations are successful? Are exceeding some buffer size (maybe 2 GB large)? Or are you counting bytes in some way with a signed int?

Just a few ideas. As I said, if you haven't changed the loopback example, odds are that the problem is with the test program or file size. In case of doubt, I suggest creating a named pipe, and run the test on that. I bet the problem will remain.

Regards,
Eli

[Guest]

Thank you Eli,

Again, you were right. I should asked this the first day I saw this issue... waste a whole week...

I work in Windows it is the operating system 2GB limits... still have no clue how to address it though.

Best,
Chongxi