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List:       u-boot
Subject:    [U-Boot-Users] how does stack work?
From:       kenneth.c.johansson () ericsson ! com (Kenneth Johansson)
Date:       2004-07-27 17:31:46
Message-ID: 41069182.6030704 () ericsson ! com
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Seingier Fran?ois-Xavier wrote:

> hello,
> I'm trying to understand how the initial stack works on a ppc4xx. According to \
> start.S this is how the layout looks to me: ___________
> > > 
> > > 
> > > 
> > gd_t   |
> > ___________|  
> > 0     |
> > ___________|  
> > 0     |  
> > ___________|<-+
> > reset_vec |  |
> SP ->|___________|  |
> > > --+
> > ___________|<-+
> > > > 
> > ___________|  |
> > > --+
> > ___________|
> > ...     |
> 
> I can't figure out precisely how the last stack frame works:
> - /* clear final stack frame so that	*/
> /* stack backtraces terminate cleanly	*/
> I'm not sure to understand the "terminate cleanly".
> 
> 
Some debug tool that get confused ??

> - why will the reset_vec be used in case of a stack underflow?
> I tried to find an answer in the "PowerPC compiler writer's guide" about the ABI, \
> but I am not even sure gcc uses an AIX or System V implementation... 
> 
You can not return from the first function but for some unknown reason 
you do that what should happen ?? a reboot is probably as good as anything.

The ABI for  u-boot is eabi
ftp://ftp.funet.fi/pub/mirrors/sourceware.cygnus.com/pub/binutils/ppc-docs/


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