Honored Contributorexcuse me. in altera PR user guider, it usually specified one column to be the Partial reconfiguration region?
could I ask you a question, what is the minimum granularity in the board? Is one whole column or other? Thank you for your reply
Honored ContributorThis is a very good question and it would be nice that one of the gurus reply.
Is it possible to reconfigure a single frame or the finest granularity is one column ? In addition, while a part of a column is being partially reconfigured does the rest of it keep its functionality taking into account that the entire column has to be reconfigured ? Cheers, StefHonored ContributorHi! I'll try again. Is it possible that Altera does not have support for PR ? It is a very important topic nowadays and I wouldn't like to change to Xilinx since I like other features a lot.
Some guru should be able to provide some support here and answer our questions. Hope to hear from you soon. Cheers, StefHonored ContributorHello,
there is dynamic partial reconfiguration at least in the Stratix V devices. About the other boards, there's not much info around the internet. You can define partial reconfiguration regions as being any LogicLock region afaik. The configuration happens column-wise. In other words, even if your PR region is as small as 3x3 wide, the partial bitstream would still comprise at least 1 or 2 vertical passages on the so-called CRAM frames (http://quartushelp.altera.com/14.0/mergedprojects/comp/comp/comp_about_part_reconfig.htm). There's not much info about what actually comprises a CRAM frame though and it would be interesting to know, since the number of CRAM frames inside a partial bitstream directly affects the bitstream size and reconfiguration time.Honored ContributorHi comododragon,
Thanks for the post. Yes, I know that Altera FPGA can be reconfigured, actually I managed to design something partially reconfigurable but my question is about the granularity. I am sure that in a column (vertical passage as you called it) there are more than 1 frame. That's why I asked whether it is possible to reconfigure a single frame like in Xilinx FPGAs or the smallest portion is 1 vertical column. I'd like to change only few CRAM bits within a single frame and not the entire column.Honored ContributorOk, I think we (or just me) are having some naming confusion here. I understand a column as being a single column of LABs or DSPs or memory cells, etc. I understand a CRAM frame as being composed of one or more (here's the catch, I don't know this quantity) of these columns. Anyone that has better understanding about this should take a look on our discussion.
What I know is that independent of your logiclock size, the partial bitstream is always a multiple of CRAM frames, with the size and reconf. time depending on which mode you use for your bitstream (SCRUB for non-vertically-overlapping PR regions but half the size, or AND/OR for vertically-overlapping PR regions). In other words, there's no way of reconfiguring just a portion of a CRAM frame. I've understood this from the Partial Reconfiguration Online Course available @ Altera's website. Please anyone correct me if I'm wrong, I've entered this PR world this month :PHonored ContributorSorry, OF COURSE there's a way to reconfigure just a portion of a CRAM frame, but the bitstream will always comprise CRAM frames as wholes, considering both static and PR region within the frames (it'll ignore messing on static regions and it'll clear-and-set pr region).
Honored ContributorYou are right! We should first define some things:
- column : single column of LABs or DSPs or memory cells... I agree. A vertical column that can be seen in ChipPlanner. - frame : A subset of a column, i.e. a column is composed of 20+ frames which cannot be seen ChipPlanner. Not documented. In Xilinx FPGAs each column is composed of several frames. In addition, it is the smallest granularity that can be reconfigured. I watched the online course as well and nothing has been said about the frames. It seems that one can only reconfigure an entire column in 2 modes you mentioned and not a part of it, ie. a frame.Honored ContributorOk, that's the opposite of what I thought. I thought that one frame was composed of many columns. Nevertheless, this is a very obfuscated field and it'd be nice to have some more info about it, at least how many frames are inside a column and/or how many compose a Stratix V, for example.
Honored ContributorExactly. That's why I reactivated this thread since it is a hot topic and Altera has to provide more information since in my opinion they are getting better and better!
