> On 13 Feb 2018, at 21:50, Christophe Fontaine <christophe.fonta...@enea.com>
> Hi Andrew !
> Happy to see someone else tried to play with the rpi ;)
I wanna try VPP in my home network, but don’t have a lot of b/w (just 2x50mbps
with two ISPs), I am very strict about the power consumption for the “always
on” gadgets, that’s the motivation to try to squeeze it on something small and
see what happens :-)
> I'm guilty for the initial work 1 year ago, but as you saw, I did not tried
> to keep up with the development.
Your work was of big help to get started, thanks a lot ! :-) though I could not
dig enough into the archive to see whether “arm32” platform was specific to RPi
or it was something more generic, so I went with a new platform file.
> For the rpi timercode, it was mainly to have something standard, based on the
> aarch32 arch, but one thing worth mentioning is that I used a rpi2 (which is
> not a aarch64 running in aarch32 mode.)
> But this does not exclude a specific mess-up from my side ;)
Oh, if you still have the h/w, would be curious to compare whether you also can
observe this discrepancy in time... on my RPi3 with the kernel module, the
“make run” would sporadically hang/crash, and since that was the timer, I just
made a cycle taking the clib_cpu_time_now(), doing sleep(1), taking another
time, and printing the difference... maybe the behavior somehow has changed
> -----Original Message-----
> From: firstname.lastname@example.org [mailto:email@example.com] On Behalf Of Andrew
> Sent: Tuesday, February 13, 2018 6:29 PM
> To: firstname.lastname@example.org
> Subject: [vpp-dev] Experiments in compiling and running VPP on Raspberry Pi
> Hi all,
> This past weekend (which coincided with the start of my vacation) I have
> decided to spend a day to see if I can get VPP to compile and run on
> Raspberry Pi.
> After a few cuts with a blunt pen knife, I got it working - it compiles
> entirely on RPi 3 itself and I can get it to the "make run", create tap
> interfaces, and ping the linux side. Other than also testing VAT (it works. I
> could create a couple of ACLs/assign them to interfaces) I did not yet test
> anything more sophisticated, so - no warranties whatsoever ! :-)
> I had a "real" HDD mounted as a checkout root - not sure how well it would
> work using the flash, but probably should not be a problem. The only other
> thing worth mentioning - I learned RPi has a "thermometer" onscreen display
> sign, during the compile :-) The temperature of the CPU has reached 84C (aka
> "don't touch!"), that was *with* the heatsink. So, ensure you have a good
> heat sink !
> I've captured the current state of my experiments here:
> I boot the RPi with the additional "isolcpus=2,3" on the kernel command line.
> I didn't test yet without that change. For the rest - it's a vanilla Raspbian
> Lite image.
> One note: reading the archives / wiki
> I saw the mention of the kernel module. When I ran the code with it, I saw
> very flaky behavior, and frequent lockups/crashes.
> My debugging concluded that probably having the rdtsc deltas over a one
> second interval vary more than 10x over the consecutive periods of time is
> what makes the timer code very unhappy. Not sure if this is specific to the
> hardware I have or to the way it works in RPi in general.
> Anyway, I found a way to create a very crude but more stable replacement -
> RPi appears to have a 64-bit 1Mhz free-running timer/counter. Multiply that
> value by 1200... With that there were no more mysterious
> instabilities/crashes. As a bonus - no need to load the kernel module, so the
> process is simpler. Probably the performance implications of that for running
> on Pi will be nontrivial, but it is surely better than crashing.
> Next 2.5 weeks I won't hack on this further (sightseeing/skiing will take
> precedence - vacation!), so figured I'll use this time to hear what you all
> think :-)
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