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RE: Redboot causes PCI abort in Linux Ixp425


Yes, you are correct about the ADI Coyote board.  Almost all of our other
platforms scan PCI devices in RedBoot and Linux makes use of the RedBoot
scan.  The opposite is true of Coyote where RedBoot does no scanning and
Linux does the scanning.  Because it's the exception for us, I often forget
that.

You may want to try creating a simple data abort handler that captures the
PCI status and the PC of the offending instruction.  There should be a data
abort handler for PCI scans in some eCos HALs that you can use as an example
for your case.  The PCI status may tell you that you are getting a master
abort or some other type of PCI error or it may have no error, in which case
it could be the address you are using to access the device (make sure it's a
proper virtual address that maps to the correct physical address) or perhaps
some register in the IXP425 is not setup correctly.  

Stephen Goadhouse  
Senior Staff Engineer  
ADI Engineering (http://www.adiengineering.com)
(434) 978-2888 x254

  

> -----Original Message-----
> From: Ravi modgekar [mailto:ravilm@yahoo.com] 
> Sent: Wednesday, March 22, 2006 9:21 AM
> To: Stephen Goadhouse; ecos-devel@sourceware.org; 
> ecos-discuss@sourceware.org
> Subject: RE: [ECOS] Redboot causes PCI abort in Linux Ixp425
> 
> Hi Stephen,
>    Data abort exception during PCI scan is ok.But in my case, 
> the abort does not happen while scanning the bus , but it 
> happens while accessing the device!!!!
>    Basically Linux does the PCI enumeration at the boot time 
> and sets up the device properly.There is absolutely no 
> problem while scanning.The abort happens only when you try to 
> access the PCI device.Now when you are trying to access the 
> device , there is no question of scanning the bus again.
>   I am wondering , if I am missing something else in the 
> redboot .I also don't see any need to scan the PCI bus in the 
> redboot, since linux is re doing it for me.what could be wrong.
>   By the way, I think even the ADI coyote board does not scan 
> the PCI bus in Redboot.
> 
> Regds
> Ravi
>    
> 
> --- Stephen Goadhouse
> <stephen.goadhouse@adiengineering.com> wrote:
> 
> > 
> > Xscale processors, and perhaps other ARM-based processors, 
> will get a 
> > data abort exception while scanning the PCI bus.
> > This is normal.  To
> > scan the bus, the system should be trying to read every 
> available PCI 
> > configuration slot address to see if a device is there.  If 
> no device 
> > is there, you'll get a data abort exception because technically the 
> > PCI transaction did not complete (no target to handle the PCI 
> > configuration read).  Typically, this is handled by 
> installing a data 
> > abort exception handler prior to scanning the bus that gracefully 
> > handles these exceptions during PCI bus scan.  Another alternative 
> > with the IXP425 may be to setup its internal PCI bridge so that it 
> > returns 0xFFFFFFFF instead of doing a data abort.  I have 
> not looked 
> > at the
> > ixp425 manual in a
> > while, but I am fairly certain that it has this ability.  I would 
> > expect that's what your old RedBoot did to handle this so 
> that Linux 
> > would not have to.  Receiving 0xFFFFFFFF when reading 
> non-existent PCI 
> > slots is what happens in a PC environment and I'm fairly 
> certain that 
> > is what
> > Linux typically expects.   
> > 
> > 
> >
> _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
> >  
> > _/  Stephen Goadhouse                 Work: (434)
> > 978-2888 x254 _/
> > _/  Senior Staff Engineer
> > stephen.goadhouse@adiengineering.com _/
> > _/  ADI Engineering              
> > http://www.adiengineering.com _/
> >
> _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
> > 
> > 
> > 
> > > -----Original Message-----
> > > From: ecos-discuss-owner@ecos.sourceware.org
> > > [mailto:ecos-discuss-owner@ecos.sourceware.org] On
> > Behalf Of
> > > Ravi modgekar
> > > Sent: Thursday, March 16, 2006 1:04 AM
> > > To: ecos-devel@sourceware.org;
> > ecos-discuss@sourceware.org
> > > Subject: [ECOS] Redboot causes PCI abort in Linux
> > Ixp425
> > > 
> > > Hi,
> > >    I have an  IXP425 based board based on
> > Gateworks
> > > GW2345 board.This
> > > board already had a redboot image programmed
> > through which
> > > we could easily load linux and work on it.
> > >   Now I have compiled the redboot for our IXP
> > based board
> > > from the Avila redboot sources.With this newly
> > compiled
> > > redboot I am able to
> > > boot linux, but unfortunately the PCI   cribs and
> > the
> > > linux crashes
> > > with PCI abort. The error message being "!!!
> > > abort_handler addr =
> > > 0x40015000 ,isr = 0x0 , status = 0x22a0".
> > > Interestingly the same Linux
> > > image works fine with the old redboot ,for which
> > we don't
> > > have the source code.
> > >   Has anybody in this list faced this problem.Am I
> > missing
> > > configuring something in the Redboot  which is
> > causing the
> > > PCI abort.I have tried with completely disabling
> > PCI
> > > interface , but I still see this problem.
> > > 
> > >  any pointers !!!
> > > 
> > > Regds
> > > Ravi
> > > 
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> 
> 
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