PCIX DMA Serverworks chipset

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I'm using the Xilinx PCI-X core (64bit/133MHz) on an add in card to
perform a DMA from the card into the system's memory. The user
application in the FPGA requests 4Kbyte bursts and after transfering the
4Kbyte it gets a new address from the device driver.
This application works well in a PC with Intel E7505 memory controller
and P64H2 bridge. We achieve a datarate of about 450 MB/s. But it
doesn't work in a HP Proliant DL380 with Serverworks Grand Champion LE
chipset and CIOB-X2 bridge. In this system we only can transfer data for
some seconds if the blocksize of the DMA is reduced to 1 Kbyte and then
the system suspends and has to be rebooted.
Does anyone have experience with a dma application on such a system?
Thank you,

Re: PCIX DMA Serverworks chipset
We are debugging similar types of issues with a Xilinx based PCI-X card and the
chipsets you mention. There are numerous possible causes for the general symptom
you describe. I presume these are dual Xeon chassis' you are talking about? Make
sure your s/w guys understand read/write ordering and use of semaphores in
multi-threaded applications and SMP systems.

My first suggestion is to get the documentation for the PCI-X bridge that you
are interfacing with. For the particular chipset that you describe that could
prove difficult :).

My second suggestion is to buy one of these (or something like it):


and hook it up to your logic analyzer (you can rent one too, that's what we
did). Being able to observe what's going on on that bus will save you a _lot_ of
debugging time.


Matthias Mller wrote:
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