Support does appear to be present but there is a problem returning back to
user space I suspect.
What fails is it causes Linux user space programs to get Segmentation
errors.
Issuing a simple ls causes a segmentation fault sometimes. The shell gets
terminated
and you cannot log back in. INIT: Id "T0" respawning too fast: disabled
for 5 minutes pops up.
However, the critical interrupt handler keeps running. I know this by
adding the reading
of a physical I/O location in the handler and can see it is being read on
the scope.
The only code in the handler is below.
void critintr_handler(void *dev)
{
critintrcount++; // increment a variable
iodata = *piom; // read an I/O location
mtdcr(0x0c0, 0x00002000); // clear critical interrupt
}
Below is a log of the type of crashes that occur:
root@10.34.9.213:/opt/ppmac/ktest# ls
Segmentation fault
root@10.34.9.213:/opt/ppmac/ktest# ls
Segmentation fault
root@10.34.9.213:/opt/ppmac/ktest# ls
Makefile ktest.c ktest.ko ktest.mod.o modules.order
Module.symvers ktest.cbp ktest.mod.c ktest.o
root@10.34.9.213:/opt/ppmac/ktest# ls
Debian GNU/Linux 7 powerpmac ttyS0
powerpmac login: root
Debian GNU/Linux 7 powerpmac ttyS0
powerpmac login: root
Debian GNU/Linux 7 powerpmac ttyS0
powerpmac login: root
Debian GNU/Linux 7 powerpmac ttyS0
powerpmac login: root
Password:
Last login: Thu Nov 30 20:42:16 UTC 1933 on ttyS0
Linux powerpmac 3.2.21-aspen_2.01.09 #10 Mon Aug 19 08:49:12 PDT 2013 ppc
The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.
Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
INIT: Id "T0" respawning too fast: disabled for 5 minutes
----------------------------------------
From: "Benjamin Herrenschmidt" <b...@kernel.crashing.org>
Sent: Saturday, August 17, 2013 3:05 PM
To: "Kumar Gala" <ga...@kernel.crashing.org>
Cc: linuxppc-dev@lists.ozlabs.org, hbaus...@deltatau.com
Subject: Re: Critical Interrupt Input
On Fri, 2013-08-16 at 06:04 -0500, Kumar Gala wrote:
> The 44x low level code needs to handle exception stacks properly for
> this to work. Since its possible to have a critical exception occur
> while in a normal exception level, you have to have proper saving of
> additional register state and a stack frame for the critical
> exception, etc. I'm not sure if that was ever done for 44x.
Don't 44x and FSL BookE share the same macros ? I would think 44x does
indeed implement the same crit support as e500...
What does the crash look like ?
Ben.
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