Re: performance monitor exceptions

benh@kernel.crashing.org wrote:

 - I don't know how the perf. mon stuff works, but couldn't you
enter a condition were the CPU is continuously sending your the
pef monitor exception until you clear something else ?

No, in a performance monitor exception, PMXE (PM exception enable)
is cleared in MMCR0, and I need to set it explicitly to get another
exception. The only performance event source that's enabled is the
one using the timer base, so this gives me exceptions at 200 Hz,
more if I want.

 - I encountered a problem with the TAU stuff and the 7400 where
the CPU could actually get mixed up when getting both a normal
interrupt and a TAU exception and scew up itself (by taking both
exceptions and screwing up SRR0/1)

Bingo ! That seems to be the one:

http://www.mot.co.jp/SPS/html/lit/pdf/mpc7410pns_rev0.pdf

  #5:
  Description: Consecutive Performance Monitor, Decrementer,
  or Thermal Management Interrupts may become non-recoverable.

  Work-Around: Avoid enabling any combination of
  Performance Monitor, Decrementer, or Thermal Management
  Interrupts at the same time.

Hmm, working around this will be tricky ...

Thanks a lot !

- Werner

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  _________________________________________________________________________
 / Werner Almesberger, Lausanne, CH                    wa@almesberger.net /
/_http://icawww.epfl.ch/almesberger/_____________________________________/

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Bingo ! That seems to be the one:

http://www.mot.co.jp/SPS/html/lit/pdf/mpc7410pns_rev0.pdf

  #5:
  Description: Consecutive Performance Monitor, Decrementer,
  or Thermal Management Interrupts may become non-recoverable.

  Work-Around: Avoid enabling any combination of
  Performance Monitor, Decrementer, or Thermal Management
  Interrupts at the same time.

Thats rather ugly :( BTW I have run kernel profiling off the performance
monitor exception on ppc64 which has been very useful (it allowed us
to profile inside interrupt disabled regions)

Anton

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Thats rather ugly :( BTW I have run kernel profiling off the performance
monitor exception on ppc64 which has been very useful (it allowed us
to profile inside interrupt disabled regions)

A workaround for pmac or openpic ppc32 is to use the keylargo or the
openpic timer instead of the DEC. That could be a "kernel hacking" option

Ben.


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On Wed, 13 Feb 2002 benh@kernel.crashing.org wrote:

A workaround for pmac or openpic ppc32 is to use the keylargo or the
openpic timer instead of the DEC. That could be a "kernel hacking" option

Speaking of OpenPIC....  I tried to build a kernel from BK TOT last night
for a PowerMac G4, and it hung about a half screen into booting after some
yammering about OpenPIC.

openpic enter
openpic timer
openpic ext
(hang)


Is there a 2.4 kernel source tarball around that is known to boot on
Sawtooth (using BootX)?  Is there a way to yank the OpenPIC support?


David

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quoted

A workaround for pmac or openpic ppc32 is to use the keylargo or the
openpic timer instead of the DEC. That could be a "kernel hacking" option

Speaking of OpenPIC....  I tried to build a kernel from BK TOT last night
for a PowerMac G4, and it hung about a half screen into booting after some
yammering about OpenPIC.

openpic enter
openpic timer
openpic ext
(hang)


Is there a 2.4 kernel source tarball around that is known to boot on
Sawtooth (using BootX)?  Is there a way to yank the OpenPIC support?

BootX isn't supported on any newworld mac. You should boot from OF,
using yaboot.

Ben.


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quoted

quoted

Is there a 2.4 kernel source tarball around that is known to boot on
Sawtooth (using BootX)?  Is there a way to yank the OpenPIC support?

BootX isn't supported on any newworld mac. You should boot from OF,
using yaboot.

BootX works fine for me with every 2.2 kernel I've tried.  It only fails
for 2.4 TOT builds.  I very much doubt the boot mechanism is at fault.

Well, it can be for various reasons. For example, the interrupt tree
cannot be properly parsed, we don't get the OF "phandles" and we now
rely on them (MacOS don't keep them when it gets the device-tree).
Also, some bus mastering devices aren't properly shut down, potentially
screwing things up in memory while the kernel loads.

I would really recommend you give a try to yaboot before investigating
much further.

(Note: I do have a sawtooth here which just works with latest kernels)

Ben.


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On Wed, 13 Feb 2002 benh@kernel.crashing.org wrote:

quoted

Is there a 2.4 kernel source tarball around that is known to boot on
Sawtooth (using BootX)?  Is there a way to yank the OpenPIC support?

BootX isn't supported on any newworld mac. You should boot from OF,
using yaboot.

BootX works fine for me with every 2.2 kernel I've tried.  It only fails
for 2.4 TOT builds.  I very much doubt the boot mechanism is at fault.


Later,
David

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