mpc8xx-2.2.13 booting problem

Clinton Lam clinton at
Fri Feb 4 12:25:57 EST 2000


After another 5 hours of debugging, I've narrowed the problem to the
decrement counter interrupt. For some unknown reasons, the interrupt never
gets clear. The system just keep looping and waiting for this interrupt to
be cleared.

In the file time.c (this is the file where all of the timer interrupt code
is), it mentions something about making an assumption that MBX board is
running off a 32.768KHz crystal. But the Touchstone board has a 3.57 MHz
crystal. So, something has to be changed to make this work! Anyone has any

BTW, the network bootloader is modified from a comercial OS. We use it to
jump start our project. I don't think we can share the code with everyone,

Clinton Lam

> -----Original Message-----
> From: Alan Mimms [mailto:alan at]
> Sent: Thursday, February 03, 2000 10:03 AM
> To: Clinton Lam; Linuxppc-Embedded (E-mail)
> Subject: Re: mpc8xx-2.2.13 booting problem
> Clinton,
> This function enables interrupts.  Some bit of hardware is leaving an
> interrupt asserted permanently, or else your port or your
> driver for some bit
> of hardware is not turning off the interrupt request by
> servicing the interrupt
> properly.  Or, possibly, your 8xx interrupt management is screwed up.
> One of those explanations is it, just about guaranteed...
> Luck.
> a
> On Thu, 03 Feb 2000, Clinton Lam wrote:
> > Hi,
> >
> > I am new to the embeded linux. I am trying to port
> mpc8xx-2.2.13 kernel to
> > our custom board, called Touchstone. It is a reference
> design based on
> > mpc823, which has 32 Mbyte of SDRAM, and 4 Mbyte of flash.
> >
> > So far, I've developed a network bootloader, which
> downloads the zImage to
> > the target. I am at the stage where I can unzip the kernel
> image to address
> > location 0x0, and jump to it. Then, inside the routine
> "start_kernel", I am
> > able to get the console up and have the linux banner
> partially displayed at
> > the cosole.
> >
> > However, after some more kernel initialization in
> "start_kernel", the
> > program stuck in a routine called "sti()". I've debugged
> through this
> > routine (it is an assembly routine) , and it seems that it
> is looping
> > forever inside the routine. I know that the routine is
> trying to set the EE
> > bit in MSR, and also doing some thing with
> ppc_n_lost_interrupts, which I
> > don't quite understand.
> >
> > Does anyone have any idea what is wrong with my port? Can
> someone explain to
> > me what is the purpose of this "sti()" routine, what are
> the possible cause
> > for it to hang?
> >
> > Your response is greately appreciated!
> >
> > Thanks in advance.
> >
> > Clinton Lam
Alan Mimms     Packet Engines, Inc.     Spokane, Washington [99214-0497]
  USA, Earth, Sol, Milky Way, The Local Group, Virgo Supercluster, U0
Despite the cost of living, have you noticed how popular it remains?
  -- Steven Wright?

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