Sorry, I missed your original question: There's a very complex tradeoff with these cores, in terms of clock speed of the processor, clock speed of the FPU, errata workarounds, etc. Generally, In V4, DP floating point code ends up about the same speed whether you use the DP core and accept the system limitations or just use a well tuned DP floating point emulation library with the core frequency as fast as possible: hence we usually recommend for most purposes, people use the floating point emulation libraries in V4 for double precision. My understanding is that the IBM libraries are significantly better than the gcc libraries in this respect...
Steve > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:linuxppc-embedded- > [EMAIL PROTECTED] On Behalf Of Grant Likely > Sent: Wednesday, September 17, 2008 10:36 AM > To: Shanyuan Gao > Cc: linuxppc-embedded > Subject: Re: Back port Virtex5 FPU to Virtex4? > > On Tue, Aug 26, 2008 at 04:00:42PM -0400, Shanyuan Gao wrote: > > I am working with ML410 and have FPU (single precision) working. > > However, the FPU for V5 looks more attractive because it's double > > precision. So is it possible to back port the double precision FPU to > > V4? > > As far as I understand there are limitations in the V4 APU interface > that makes the full double precision FPU unfeasible. The Xilinx folks > can correct me if I'm wrong. > > g. > _______________________________________________ > Linuxppc-embedded mailing list > Linuxppc-embedded@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-embedded This email and any attachments are intended for the sole use of the named recipient(s) and contain(s) confidential information that may be proprietary, privileged or copyrighted under applicable law. If you are not the intended recipient, do not read, copy, or forward this email message or any attachments. Delete this email message and any attachments immediately. _______________________________________________ Linuxppc-embedded mailing list Linuxppc-embedded@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-embedded