MVME3100 FPU Support on RTEMS 4.10.2
mdavidsaver at gmail.com
Wed Jun 6 21:28:58 UTC 2018
On 06/06/2018 02:24 PM, Matt Rippa wrote:
> Thanks for the fast reply. Of all the mvme boards you listed,
> the 3100 hits a nice price point and we're attempting to find
> suitable replacement stock
> (quantity 30+)
> for the 2700 which are no longer
Last I checked (~5 years ago) the newer mvme2500 had a price similar to the mvme3100.
The issue was software support. At the time there didn't seem to be RTEMS board
> Are the 6100 boards on beatnik bsp the only remaining option for RTEMS?
> They cost nearly twice as much and have
> thermal regulation issues.
> On Wed, Jun 6, 2018 at 11:10 AM, Michael Davidsaver <mdavidsaver at ospreydcs.com <mailto:mdavidsaver at ospreydcs.com>> wrote:
> Hi Matt,
> The MVME3100 is based on the MPC8540 processor. This chip doesn't have an FPU.
> Other boards do (eg. mvme270x, mvme6100, or mvme2500) and RTEMS supports this.
> I can certainly confirm that lack of an FPU really hurts performance, even
> something as (apparently) simple as integer to float.
> On 06/06/2018 02:03 PM, Matt Rippa wrote:
> > It appears we've compiled our mvme3100 bsp without FPU support.
> > We're on the mvme3100 running EPICS 22.214.171.124 and RTEMS 4.10.2.
> > We're attempting to commission our astrometric kernel control system
> > and we've run into trouble meeting some of our thread deadlines. What
> > we've found is a transform routine that takes our mvme2700 ~200 us,
> > takes the mvme3100 ~8 ms. So not a surprise to see this with only "-msoft-float"?
> > ...
> > 2018-05-31-tcs.log:May 31 11:41:15 E) PORT: tcs_vme, MSG: Welcome to rtems-4.10.2(PowerPC/Generic (*no FPU*)/mvme3100)
> > Is FPU support possible with RTEMS 4.10.2? If so, what would we need to do?
> > It looks like there's a multilib on 4.11.2 https://docs.rtems.org/releases/rtems-docs-4.11.2/cpu-supplement/powerpc.html#multilibs(*Eg <https://docs.rtems.org/releases/rtems-docs-4.11.2/cpu-supplement/powerpc.html#multilibs(*Eg>., see #13* )
> > Here's our bsp specs:
> > beatnik:
> > -specs bsp_specs -qrtems -fasm -c -mcpu=7400 -D__ppc_generic -DUNIX -O2 -g -g -Wall
> > (mvme2700) mvme-2307:
> > -specs bsp_specs -qrtems -fasm -c -mcpu=604 -mmultiple -mstring -mstrict-align -meabi -DUNIX -O2 -g -g -Wall
> > mvme-3100
> > -specs bsp_specs -qrtems -fasm -c -mcpu=powerpc *-msoft-float* -D__ppc_generic -DUNIX -O2 -g -g -Wall
> > Thank you!
> > -Matt
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