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Altera_Forum
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20 years ago

Clock frequency for uClinux?

I was just wondering what frequency is typically used/required for uClinux running on a Cyclone? I ask because I'm running into some problems with networking running at 66 MHz. I'm finding that usign an Opencores MAC, I am getting TX Buffer overruns - this is on custom hardware. It happens when I try to cat a large file using telnet for example... things like FTP and HTTPD seem to work ok though. I tried the same setup on an EP1C12_eval board, and it did the same thing more or less..

I am using an initramfs kernel, sothe filesystem is readily available in SDRAM... One interesting thing is that when I use the eval board and actually mount the filesystem in flash as root, it doesn't happen - one theory would be since it's not available as fast in Flash, it won't overrun the TX Buffers. But when it's in RAM, filesystem data is available a lot faster, so it has the potential to overrun maybe?? If I increase the frequency on the eval board 72Mhz, it doesn't happen - I can't do this on my custom hardware since I can't get the fmax that high.

What do you guys typically use?

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  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    --- Quote Start ---

    originally posted by jdhar@Dec 4 2005, 12:51 PM

    i was just wondering what frequency is typically used/required for uclinux running on a cyclone? i ask because i'm running into some problems with networking running at 66 mhz. i'm finding that usign an opencores mac, i am getting tx buffer overruns - this is on custom hardware. it happens when i try to cat a large file using telnet for example... things like ftp and httpd seem to work ok though. i tried the same setup on an ep1c12_eval board, and it did the same thing more or less..

    i am using an initramfs kernel, sothe filesystem is readily available in sdram... one interesting thing is that when i use the eval board and actually mount the filesystem in flash as root, it doesn't happen - one theory would be since it's not available as fast in flash, it won't overrun the tx buffers. but when it's in ram, filesystem data is available a lot faster, so it has the potential to overrun maybe?? if i increase the frequency on the eval board 72mhz, it doesn't happen - i can't do this on my custom hardware since i can't get the fmax that high.

    what do you guys typically use?

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    nm... figured it out - had to change the read size and write size http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif