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Real-Time patch for Linux

eactor

Hello I would like to apply the real-time patch to Xillinux or any other Ubuntu which I could run on the Zedboard.
Obviously Xillinux has a kernel 3.3 and the RT-Patch is only available for 3.2, 3.4, 3.6, 3.8?

Also the official Xilinx Kernel GIT is stated 3.9, but I'm unsure if the kernel would work with the Xillinux?

Could somebody shed some light on the topic?

  • 0

    Hi,

    Xillinux' kernel is based upon the one from Digilent plus the patches in /usr/src/xillinux/kernel-patches/ in Xillinux' file system. This patch set also generates the .config file (which isn't really proper, but convenient). I don't know to what extent the delta between Digilent's kernel and the vanilla one has made itself into the mainline kernel.

    What I would do if I were you:

    (1) Get myself the latest digilent kernel and the exact vanilla kernel closest after it that has real time patches available.
    (2) Rebase or merge Digilent's delta commits into the vanilla kernel (and hope for good)
    (3) Apply the real time patches
    (4) Apply Xillinux' patches.

    Item (2) may turn into a headache, but there's no way around it. No Linux kernel will work without this (unless those commits are already in the mainline kernel).

    Item (4) should be a piece of cake, because most of it just adds drivers (slight and obvious conflicts are possible).

    By all means, please tell us how it went. :)

    Regards,
       Eli

  • 0

    It worked after I played around with the order to apply the patches, but the Cyclictest (program for testing the new kernel latencies) isn't doing any better than vanilla kernel. Right now I try to find out if I considered everything. The max latency of 1500 us is way too high and I would consider everything below 300 as good.
    Cheers
    eactor

    So if someone has experience with the soft IRQ or maybe HWIRQ causing this, hints are appreciated. It is still the them behavior noticed with the shipped busy box: http://www.zedboard.org/content/busybox-hangs-every-2-secounds

    Console:
    cyclictest -t1 -p 80 -n -i 10000 -l 10000
    # /dev/cpu_dma_latency set to 0us
    policy: fifo: loadavg: 0.13 0.31 0.17 1/150 2224
    T: 0 ( 2224) P:80 I:10000 C:  10000 Min:     18 Act:   36 Avg:   32 Max:    1565