Qemu Sam460 developer need help
  • Butterfly
    Posts: 62 from 2017/9/10
    ___Please write here i will post him your help___ Thanks!


    Anyone here with knowledge about PPC440 (especially as used in AMCC460EX
    SoC that the Sam460ex board is built on)? I see some problems related to
    timers and bus frequencies which are likely not emulated correctly but I
    don't know what's wrong or missing.

    Problems I know about that may be related:

    1. System time is going slower than expected in AROS (can be seen e.g. in
    Time Prefs). The seconds advance but much slower than they should. (AROS
    boot iso can be downloaded from http://aros.sourceforge.net/nightly1.php)

    2. I had to set clock multipliers in SDR0_STRP0 register (that seems to
    have values for different internal buses of the SoC such as PLB and OPB)
    in qemu/hw/ppc/ppv440_uc.c:396 to 0 instead of a value more closely
    matching real hardware (although I'm not sure what real hardware has in
    this reg) because if I set the bits in comment for multipliers bus
    frequencies are printed correctly but this slows down U-Boot. A 0 value
    here works for U-Boot but makes the printed bus frequencies wrong. (I've
    also come across this u-boot patch
    https://lists.denx.de/pipermail/u-boot/2011-July/096848.html but haven't
    yet tried if it makes any difference.)

    3. AmigaOS 4 boots very slowly which may be related as there seem to be a
    delay in IO operations (similar to U-Boot with non-0 value in STRP0) that
    could be because of a timer going slower than expected but I'm not sure
    without source what it really does. (There also seem to be graphics
    corruption issues with AmigaOS 4 but I could not identify yet if these are
    becuase of incomplete emulation of the SM502 chip or some other problem
    caused by delays due to timing (as writing SM502 registers seem to have a
    much longer delay than expected).

    4. Linux kernel boots but hangs just before init should start. I'm not
    sure how to debug this to find out where's the problem so I'm not sure
    it's related but could be.

    So there seems to be a problem with tb and other frequencies and timers
    relying on these but I don't know what's on real hardware and how exactly
    are these emulated in QEMU. Does anyone know more about these registers
    and how it works on real hardware and has any hints what could be the
    problem here? Any help is appreciated.

    BALATON Zoltan
  • »13.03.18 - 14:32